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Tech Talk => Engine Mechanical / Electrical => Topic started by: capogniracing on May 18, 2014, 10:45:56 AM

Title: Won't rev past 4000
Post by: capogniracing on May 18, 2014, 10:45:56 AM
Hey guys new to site. Need some advice, just bought my first boat 18ft dominator with a 383 sbc  edelbrock aluminum heads, victor jr style intake, holley 650dp and jg berkeley pump. Runs great outta water, will rev to 7k with no load. Put her in the water and only revs to 4k and starts to pop and cut out. I have already replaced this so far, fuel pump that is set at 9 psi regulated, new msd hei distributor, new cam, new carb holley 650 with mechanical secondaries, use to have 600 holley vacuum secondaries, please any suggestions will help this is driving me crazy. Thanks


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Title: Re: Won't rev past 4000
Post by: 93_ultra on May 18, 2014, 12:12:29 PM
What impeller do u have? Ur jet might be limiting your setup.

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Title: Re: Won't rev past 4000
Post by: Squirrel Master on May 18, 2014, 12:28:37 PM
Small blocks dont have the torque u need for high rpm. Popping what do ur plugs look like could be lean pop
Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on May 18, 2014, 12:49:14 PM
Two very good posts... :thumbup:

First being, what impeller do you have? As even a nice small block will have trouble turning past 4k if you're slinging something like an "A" cut impeller.

And the second post... how's the tune on this thing? Also,what kind of plug gap you running? Just kinda got to run down the check list and rule out the obvious, simple, and basic before going super deep into complex diagnosis.

Title: Re: Won't rev past 4000
Post by: capogniracing on May 18, 2014, 01:14:08 PM
Will take bowl off tomorrow and check impeller and gap and will get back to you guys thanks for input. Probably just gonna end up switching too bbc if I can't figure it out.


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Title: Re: Won't rev past 4000
Post by: capogniracing on May 18, 2014, 01:49:28 PM
Kinda leaning to impeller out at Elsinore right now and she is running 55 at 3900 so I'm sure that has to be a A impeller. What impeller would you guys suggest I'm assuming I'm around 450-475 hp.


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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on May 18, 2014, 03:06:46 PM
Well... to be honest... a nice built 383 will run fairly good in a lighter small boat... but every one I have worked on typically like a much smaller impeller versus what a big block would like, even comparable hp because of the power band difference and much less torque.

a 475hp small block is going to do it all on the top end higher rpm as compared to a 475 hp big block. With that in mind... most of the small blocks I have come across like no bigger than a "B" cut on some burly nasty built strokers... and most were "C" or smaller. It really depends on where your engine makes it power and what your target rpm is going to be. I'd say, everything else being fine, and your engine is tuned and running properly... you turning 4k and your engine let's say wants to make it's power in the 6k range... I'd venture to say, you're gonna want to start at a "B/C" cut, and more than likely gonna trim it down. Triming more is waaaaay easier than adding it back on.


One thing though... having way to big an impeller won't cause an engine to "pop" or "cut out"... it's will just hit a wall and that will be all she has. You may have something else going on here as well.
Title: Re: Won't rev past 4000
Post by: BFGF Revenge on May 18, 2014, 06:04:59 PM
If your cutting out and popping under a load, then it is usually electrical...plugs, wire, cap, rotor, coil, etc could be fuel, but most likely electrical...just my two cents

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Title: Re: Won't rev past 4000
Post by: GT Jets on May 18, 2014, 07:17:43 PM
Kinda leaning to impeller out at Elsinore right now and she is running 55 at 3900 so I'm sure that has to be a A impeller. What impeller would you guys suggest I'm assuming I'm around 450-475 hp.


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You may have 450 HP at like 6,000RPM, your not making it at 4K, No way in hell.

Your set up sounds like it is having valve issues. What camshaft are you using?

I will assume you had the popping problem before you changed everything out? The motor will not pop if it is simply overloaded, detonate mabye, but not pop.

You don't say if it pops out the carburetor or the exhaust.


Get some manifold vacuum numbers, where the ignition timing tops out and battery voltage while running full out.

Small blocks will work fine, you just need to be a little more on your game.

GT
Title: Won't rev past 4000
Post by: capogniracing on May 18, 2014, 09:07:11 PM
I have put 4 trips out on it and this what I have changed 1st trip- new fuel pump, 2nd trip- new coil and plugs ac delco 44t and new altenator  3rd trip- new msd hei distributor and 650 dp. 4th- new cam comp cam xm270h, every single time I have took it out strong to 4k then starts popping out exhaust with any more throttle, the only thing haven't changed is wires but I did ohm test them. And as far as compression all cylinders are around 152-155.  Voltage is 14 consistent, and to be honest ran better with holley 600. And she does run strong to 4k and starts popping if I try to push it any further. And will cruise all day at 3500 with no pop. Gonna check timing again tomorrow and plug gap. What do you guys suggest so I can compare it with what I have now.


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Title: Re: Won't rev past 4000
Post by: 93_ultra on May 18, 2014, 09:21:11 PM
Power valve?

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Title: Re: Won't rev past 4000
Post by: Ckaz21 on May 18, 2014, 09:49:58 PM
Man I had the exact same problem last year. Tried everything to fix it. Nothing worked. Carbs, fuel, fuel pumps distributors, adjusted the valves 3x. Nothing worked. Ended i pulling the engine apart and rebuilt everything. My cam looked a little pitted on a couple lobes so that may have been it but the machine shop I took my heads to said I have a bad intake valve. It weird sometimes it wont show on a comp test. If you have time maybe pull your heads and get them inspected.


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Title: Won't rev past 4000
Post by: capogniracing on May 19, 2014, 03:02:41 AM
Ya that might be it I did replace the cam because I went to do the vavles after 3rd trip and had a bad lobe on number 8. Did you do a leak down test before you pulled motor apart? Might wanna add it was backfiring through carb before I put came in and does not anymore. @ckaz21 did your rev all the way out outta water.


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Title: Re: Won't rev past 4000
Post by: Ckaz21 on May 19, 2014, 03:18:14 AM
I didn't do a leak down its a good idea though. I just did a comp test. The only other thing I suspected was that maybe I had a busted valve spring or the timing chain had become a too stretched over the years. I would highly suggest a leak down and try to inspect your valve springs, also check to make sure the advance weights in your distributor aren't stuck.


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Title: Won't rev past 4000
Post by: capogniracing on May 19, 2014, 02:28:23 PM
Well guys just took pump apart to see what she has and it's an A. Measures 7 1/4 across so it's not cut down. Anyone have a B/C or a C?? Looking more toward B/C Or know where I can get this one cut down by weekend?


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Title: Re: Won't rev past 4000
Post by: Riverlife_ on May 19, 2014, 05:41:27 PM

Well guys just took pump apart to see what she has and it's an A. Measures 7 1/4 across so it's not cut down. Anyone have a B/C or a C?? Looking more toward B/C Or know where I can get this one cut down by weekend?


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R & D Marine
1370 N Dynamics St, Anaheim, CA 92806
(714) 993-2664
 
Talk to Harold, or anyone really helpful.

They cut my A to a B/C I believe and I gained about 600rpm from the cut and another 300 from the power gains being able to get into the cam a bit more, I was stuck right around 4200rpm and now I turn a solid 5100-5200.



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Title: Re: Won't rev past 4000
Post by: capogniracing on May 19, 2014, 06:49:19 PM
Thank will give him a call tomorrow


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Title: Re: Won't rev past 4000
Post by: GT Jets on May 19, 2014, 07:24:11 PM
Well guys just took pump apart to see what she has and it's an A. Measures 7 1/4 across so it's not cut down. Anyone have a B/C or a C?? Looking more toward B/C Or know where I can get this one cut down by weekend?


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Where are you out of?
Title: Won't rev past 4000
Post by: capogniracing on May 19, 2014, 07:25:08 PM
I'm out of chino/ pomona


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Title: Re: Won't rev past 4000
Post by: Ckaz21 on May 20, 2014, 12:50:34 AM
Let us know if that takes care of your problem, im very interested.


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Title: Re: Won't rev past 4000
Post by: capogniracing on May 20, 2014, 04:40:57 AM
 Hoping this takes care of it too. For my first boat I definitely got the full dish for the meaning of boat. Lol


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Title: Re: Won't rev past 4000
Post by: MorePower on May 20, 2014, 07:37:39 AM
When you replaced the cam, did you use the comp valve springs?
I ordered a complete comp cam set, ran the new springs, ended up taking the heads to clay smith to get redone (original machine shop didn't do a good job) George tested the springs and I was only getting 80lbs of seated pressure... Those springs only had 2 hours on them.
It was the second set of new comp springs they had replaced in a couple weeks...


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Title: Re: Won't rev past 4000
Post by: capogniracing on May 20, 2014, 09:49:58 AM
No ran springs that came on the edelbrock heads. I just bought the small kit which was timing chain lifters and cam.


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Title: Re: Won't rev past 4000
Post by: capogniracing on May 23, 2014, 09:09:13 PM
Just Got an b/c cut impeller put on to try out on Sunday at Elsinore will let everyone know how it works. Hoping it does the truck if not heads come off Monday.


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Title: Won't rev past 4000
Post by: capogniracing on May 26, 2014, 06:08:27 PM
Well guys no good with impeller. But I did finally get enough ran on motor to really check plugs, she's running real lean. Gonna try a 800dp this coming up Sunday and if no change heads come off and gonna get them checked out. And no more popping just goes to 4k and pretty much hits the wall. And outta water hits 7500 like nothing.


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Title: Re: Won't rev past 4000
Post by: Flusher on May 26, 2014, 07:33:08 PM
An 800DP is not necessarily going to richen it up.  You might even lose booster signal and lean it even more.  With a single-plane intake, each cylinder is pulling from all venturi and therefore slower velocity air is flowing through each venturi.  Carbs work by vacuum signal generated by airflow through the venturi.  Making the venturi larger slows that velocity and reduces booster signal.

Is the 800DP going to cost you $$$ or do you already have it?

Just a friendly reminder, free revving your engine outta water is taking life out of your engine and pump.

Regards,

Joe
Title: Re: Won't rev past 4000
Post by: GT Jets on May 26, 2014, 07:43:02 PM
X2, jet up what you have first. Lean can cause your pop. I would step it up two jet sizes and see what happens.
Title: Won't rev past 4000
Post by: capogniracing on May 26, 2014, 07:43:39 PM
Found a rebuilt one for $250, and I usually disconnect pump if I'm gonna rev over 3500. I will check jets in carb tomorrow but everyone I'm
Looking at with 383's are running 750's or 800's. I'm just throwing anything I can at it at this point. At this point everything I have done to it at this point hasn't changed total rpms even when it had a flat cam lobe. When I went from a 600 to 650 I actually lost rpms. Needless to say it was a off shelf 650. Not sure what those come with from holley. The 600 I jetted up to 69's


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Title: Re: Won't rev past 4000
Post by: GT Jets on May 26, 2014, 07:48:08 PM
Found a rebuilt one for $250, and I usually disconnect pump if I'm gonna rev over 3500. I will check jets in carb tomorrow but everyone I'm
Looking at with 383's are running 750's or 800's. I'm just throwing anything I can at it at this point. At this point everything I have done to it at this point hasn't changed total rpms even when it had a flat cam lobe. When I went from a 600 to 650 I actually lost rpms.


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Gotta have the fuel to support the air, if you raised the CFM capability and did not jet the carburetor to the application, it was a bogus test and should be disregarded.

What most people do not take into account is that the torque curve on a jet is LINEAR. Meaning the faster it spins, the more fuel it will require while the velocity in the boosters is dropping, this means low (numerically) power valve size and larger jets than a car can uses, typically two to three jet steps.

Good luck, IMHO if you slow down you'll go faster... (meaning one step at a time, not four.)  ;)

GT
Title: Re: Won't rev past 4000
Post by: capogniracing on May 26, 2014, 07:54:10 PM
Just bought a full jet kit. Gonna try that first lol. Running outta money. Next boat I buy I'm gonna get a test run before purchase.


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Title: Re: Won't rev past 4000
Post by: capogniracing on May 26, 2014, 07:56:22 PM
And thank all you guys for help. Definitely keeping me from going completely insane over this thing.


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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on May 27, 2014, 12:54:50 PM
The carb SIZE is really not going to be your problem... a 650 dp is more than capable of supporting a 383 past 5500 rpm... now if you have some ebay special... then perhaps it may be a junker and would be a problem... but two different carbs and the same problem???

Eh... I'd be looking elsewhere.

You did mention you replace the distributor but not the wires... but the wires ohmed ok? Well, that's cool to see if they are cut or breaking down inside... but doesn't tell you if they are leaking anywhere (arcing on headers, crossfiring, etc...) and the condition of the insulator or boots. What size wire you running to the distributor? Typically an HEI is gonna need something along the lines of at least a #12 and you for sure want it getting a full 12v... any resistor wire or ballast resistor... or poor connection... or way too small of a wire... ANYTHING that will cut voltage down, will cause the distributor to not be able to provide enough power to rev under a load. Also... for it to hit a wall at 4k no matter what the change... you sure this thing is getting full throttle? I mean it sounds stupid... but most problems that kick our asses (professional and hobbiest alike) tend to be something downright as stupid and simple as the pedal doesn't go all the way... had a customer a while back all sorts of angry at me about his new motor only going to 4200rpm... as it turns out... and even me spending a while scratching my head as to WTF... the way the cable/linkage/pedal setup was... it only was getting about slightly more than half throttle. How it revs on the trailer has typically little to do with how it's gonna rev under a load... about all reving it on the trailer will tell you is if you have a mechanical problem... and even then, not always.
Title: Won't rev past 4000
Post by: capogniracing on May 27, 2014, 03:01:41 PM
Carb is brand new 650dp. Pulled it apart to see what it had in in today and jets are 73's and 67's, also has a 6.5 powervalve, #28 squirtters. I did vacumm check at idle and am around 8.5-9 So according to holley need to order a different powervalve. Wire going to distributor is a 10ga. And no resistors at all. And did check throttle linkage and is getting full throttle.


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Title: Won't rev past 4000
Post by: capogniracing on May 27, 2014, 03:19:55 PM
And wires would be the next smart thing to change. And just pulled 600 apart. Has 69's, #5 powervalve and 31 squirter.


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Title: Re: Won't rev past 4000
Post by: Flusher on May 27, 2014, 06:59:04 PM
So according to holley need to order a different powervalve.

You are going to need to do some testing (on the water) with a vacuum gauge to get the right power valve.  Unless it is blown, leave it at the 6.5 for now.  The power valve is there to open and flow more fuel when you try leg press the go pedal through the hull and the vacuum drops, causing the fuel to stop flowing through the jets until the RPMs catch up.  Select the power valve last.  Drive the boat while checking the vacuum gauge for what point there is a slight hesitation when you mash the throttle.  Then select a power valve accordingly.
Title: Won't rev past 4000
Post by: capogniracing on May 27, 2014, 07:13:08 PM
Ok will hook a vacumm gauge for this weekends test run. Any suggestions on jets and squirters?? And gonna put new plug wires to try and see if that makes a difference also.


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Title: Re: Won't rev past 4000
Post by: Flusher on May 27, 2014, 07:20:22 PM
Ok will hook a vacumm gauge for this weekends test run. Any suggestions on jets and squirters?? And gonna put new plug wires to try and see if that makes a difference also.


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I can’t remember what any of the original numbers are anymore.  As for squirters and accelerator pumps, they are pretty close out of the box.  I would start with the original sizes and get your fuel curve (jets/metering plates) right first.  Then work out any hesitation or stumbles after you get it running right.
Title: Re: Won't rev past 4000
Post by: capogniracing on May 27, 2014, 07:31:30 PM
Ok how many sizes should I go up they are 73s and 67s currently. It was really lean so I would say atleast 2-3 and go from there. Any other suggestions??


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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on May 27, 2014, 08:04:31 PM
Carb is brand new 650dp. Pulled it apart to see what it had in in today and jets are 73's and 67's, also has a 6.5 powervalve, #28 squirtters. I did vacumm check at idle and am around 8.5-9 So according to holley need to order a different powervalve. Wire going to distributor is a 10ga. And no resistors at all. And did check throttle linkage and is getting full throttle.


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How do you know it is lean? Plug reading? O2 reading? Etc...? Or just based on the "popping"? 67/73 w/6.5 valves do not seem unreasonable and are more than likely stock depending on what list number the carb is. I'd say they are going to be in the ballpark enough that you are not waaay off or a major problem. As for squirters... more than likely, you'll end up with something along the 31 or 35 range... but in all honesty... you do not need to even begin to worry about that sort of thing... that is a deal where after you get it running right, now let's work on tuning the details sort of thing. What you have is a problem... not a minor tune issue... something is just plain not right. A box stock 650 is gonna work and not cause you to only rev to 4k and pop and fart... it may run dirty... or a little lean... it may not be all it could be as far as tuning... but it's gonna run. I don't know if you've done this... but check your floats... your fuel pressure is AT THE CARB 9 psi running (not pump before the regulator)? For sure check the wires. What size are your fuel lines? Plugs... seems obvious, but new or what? Gap/number/etc..? How do the plugs look after a WOT run (pics if you got them)? What total timing are you running? And when is it full advance? That #10 wire... from the key or relay all the way to the distributor without and stops, detours, or splices along the way? There is going to be something that is obvious and glairing as far as a problem once you figure out what it is... squirter sizes are tree sort of issues... you're looking for a forest issue here.

I don't want to be the bearer of bad news... but your gonna want to exhaust any fuel delivery and ignition possibilities... because the only thing left after that is, mechanical.
Title: Won't rev past 4000
Post by: capogniracing on May 27, 2014, 08:31:33 PM
Plugs reading is my answer for lean. Checked them after I ran her to cove at Elsinore, I did check my floats today and level was really high. Poring out sight holes. Plugs are new and will double check gap on plugs. And will follow wire from distributor and make sure there isn't anything funny going on. I had timing set at 10 and 34 advanced. gonna double check that again tomorrow. And some one said previous possibility of valve springs or valve not closing. Hoping not, but that would be my last resort. And I'm running 3/8 fuel line all the way from tanks to filter to pump to carb. I did order a 4.5 powervalve today and 32 squirters to try out. Trying to get her squared away before Parker float but if not I can run her the way she is to put around.


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Title: Re: Won't rev past 4000
Post by: GT Jets on May 27, 2014, 09:12:53 PM
Plugs reading is my answer for lean. Checked them after I ran her to cove at Elsinore, I did check my floats today and level was really high. Poring out sight holes. Plugs are new and will double check gap on plugs. And will follow wire from distributor and make sure there isn't anything funny going on. I had timing set at 10 and 34 advanced. gonna double check that again tomorrow. And some one said previous possibility of valve springs or valve not closing. Hoping not, but that would be my last resort. And I'm running 3/8 fuel line all the way from tanks to filter to pump to carb. I did order a 4.5 powervalve today and 32 squirters to try out. Trying to get her squared away before Parker float but if not I can run her the way she is to put around.


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Order a 3.5 PV...  ;)
Title: Re: Won't rev past 4000
Post by: capogniracing on May 27, 2014, 09:27:03 PM
Ha ok I'm gonna have a pretty good assortment once I figure this out.


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Title: Re: Won't rev past 4000
Post by: Flusher on May 27, 2014, 10:57:53 PM
Run the filter on the pressure side of the pump, not the suction side.  On the suction side can cause the pump to starve and fuel pressure will fluctuate.  Have someone monitor your fuel pressure throughout a run

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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on May 28, 2014, 11:12:42 AM
Plugs reading is my answer for lean. Checked them after I ran her to cove at Elsinore, I did check my floats today and level was really high. Poring out sight holes. Plugs are new and will double check gap on plugs. And will follow wire from distributor and make sure there isn't anything funny going on. I had timing set at 10 and 34 advanced. gonna double check that again tomorrow. And some one said previous possibility of valve springs or valve not closing. Hoping not, but that would be my last resort. And I'm running 3/8 fuel line all the way from tanks to filter to pump to carb. I did order a 4.5 powervalve today and 32 squirters to try out. Trying to get her squared away before Parker float but if not I can run her the way she is to put around.


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If you are running the springs that came with the heads new... the eddy hydraulic spring is going to be sufficient for the cam you are running... they are roughly 115-120 on the seat and in the neighborhood of 290-300 at about .500 lift (off the top of my head) Its a generic spring that a BUNCH of cam companies and head manufactures use. So in other words... plenty of spring for the cam and intended rpm range. It is possible you may have a valve not closing, or cam going away, or several other possibilities such as severe valve train harmonics or related issues... and I would for sure not rule any of this out... but it would typically be very obvious as the thing would just plain run like shit all the time... rough idle, noisy valve train, etc... something that would allude to this sort of issue... and other than popping at 4k I do not get the impression from you that is the case.

As for the power valves and squirters... I do appreciate the fact that your willing to try anything at this point... but these are fine tune issues... and you have a big tune problem... much akin to stressing out about a splinter when your leg is cut off. Squirter is going to help/hinder the transition from idle to main circuit when you whack the throttle... if you have a stumble or it falls on it's face when you hit the throttle, then this is the area you make adjustments by either going up or down or squirter and/or accelerator pump size. It does not effect at all, what so ever the rpm range or rich/lean tune of the engine at idle/part/full throttle. As for the power valve... check this out... it is a fine tune/part throttle cruise tuning related issue... you adjust your power valve AFTER you have gotten your WOT tune/jetting set, idle mixture, your timing, and anything else that may affect vacuum at part throttle. Then, and only then, does any adjustment to the power valve have any value... as it provides enrichment under part throttle conditions all the way up to where the main jet takes over. Btw... here is something that may have not been mentioned... even IF you did need a lower than 6.5 power valve (which is doubtful that your gonna need to venture far since that cam is still going to make decent vacuum at cruise rpm)... but lets say you do... and a 5.5, 4.5, 1.5... whatever, is what you actually need... the fact is... the 6.5 would cause it to run RICH not lean as it would be open more often and a lot sooner... a 6.5 takes more vacuum to hold closed (in lean position) than lets say a 4.5. The point is... if you are in fact lean... this is not why. Now a power valve that is too low in relation to the vacuum.. like needing a 10.5 and having a 6.5... will cause a lean condition when in cruise rpm... but the second you whack the throttle and go to WOT... unless you have a super small cam or crazy small carb... something that will create a lot of vacuum even under WOT condition... even then the power valve will open and richen up the system. So... no offense... and truly not trying to be a jerk or anything... I just think you have a bigger problem to sort out before worrying about fine tuning... and if you focus on these things... you're not gonna get anywhere near your bigger problem.

So... personally, if it were me... I'd just keep running down your check list and verify each and every thing is right before tearing into it.

*Compression test? if you have a bad seal... or valve holding open... or cam going to shit... it will appear here.
*Vacuum check? Steady? Bouncing? Dropping? etc... (this actually can tell you quite a bit about the condition of the insides of your engine sealing and running state)
*Verify timing? Steady? Bouncing around? Of course (I hope) you set this w/o the vacuum advance as it doesn't work in a boat.
*Ever check those plug wires? Yes, they may ohm ok... but that doesn't mean they aren't acring somewhere, which WILL act as a rev limiter
*Fuel pressure AT CARB under WOT?
*Tach working properly? Besides not reading or not reading correctly... I have also see where they were shorted out inside and acted like a rev limiter
*Full interrupted 12v to the HEI at all times? having the voltage drop under power will cause ignition issues under load and for sure not allow the engine to rev.
*Plug gap? I'd say with an HEI and moderate compression... a gap of .035ish should be just fine and a reasonable place to start.
*Cap/rotor/module/coil all ok? I believe you said it was new... but have you physically checked all this? I've seen "new" stuff from places like Summit actually been returned items and had bad parts/broken inside... it sucked huge... but they always make it right, after you find the problem.
*As weird as it may seem for me to ask... are you sure your timing mark is correct to TDC? Harmonic balancers can spin... especially 400 external balance outer rings... just a thought. May want to verify this.

Etc...

You're gonna find it... and it's gonna be something that you're gonna go, "REALLY?!?!?" ???

If you were a little closer... I'd say bring it by and we can throw an extra set of eyes on it and see if there is something you've over looked.

Title: Won't rev past 4000
Post by: capogniracing on May 28, 2014, 11:30:51 AM
Wow, thanks that is a hell of a check list. Gonna start going down the list and verify everything I can by Saturday. It has to something small. I will keep you informed of what everything is as I go down the list. And thank you for your all the info. Double checking all this something has to get better.


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Title: Re: Won't rev past 4000
Post by: capogniracing on May 28, 2014, 10:38:39 PM
Ok ask stupid as this sounds and I'm sure its a way over looked item, I went to switch around the lines from tanks to filter to pump to carb "don't know why previous owner had it that way" and changed it to above statement from flusher, tanks to pump to filter to carb and went to turn the key on and what happens........ The bottom of the damn filter started blowing holes through it cause it is now pressured. Wtf... Can't believe I over looked it. Bottom of filter is rusted out. I am hoping and praying that this was the problem for hitting a wall. Needless to say I bought boat and found out it had a flat cam and did burn up one coil, so boat did have other problems, can't wait to take it out and see if this was it. But on upside I know most everything about the motor minus bottom end.


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Title: Re: Won't rev past 4000
Post by: 93_ultra on May 28, 2014, 11:58:31 PM
Ok ask stupid as this sounds and I'm sure its a way over looked item, I went to switch around the lines from tanks to filter to pump to carb "don't know why previous owner had it that way" and changed it to above statement from flusher, tanks to pump to filter to carb and went to turn the key on and what happens........ The bottom of the damn filter started blowing holes through it cause it is now pressured. Wtf... Can't believe I over looked it. Bottom of filter is rusted out. I am hoping and praying that this was the problem for hitting a wall. Needless to say I bought boat and found out it had a flat cam and did burn up one coil, so boat did have other problems, can't wait to take it out and see if this was it. But on upside I know most everything about the motor minus bottom end.


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👍 hope it works out for ya!

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Title: Re: Won't rev past 4000
Post by: Ckaz21 on June 01, 2014, 03:22:10 PM
Well did that take care of it?


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Title: Re: Won't rev past 4000
Post by: capogniracing on June 01, 2014, 07:38:11 PM
No just got back from Elsinore. Didn't change anything even tried a different inline filter. Fuel pressure is 9 at wot. Timing is good, plugs are good checked plug gaps. Changed plug wires. Even tried a lil jetting and got it up to 4200 a couple times. Runs strong to 4000. Only thing I can think of now is valve train. Thinking it would be good to just get heads checked out.


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Title: Re: Won't rev past 4000
Post by: 1975_Challenger_461 on June 01, 2014, 07:47:00 PM
Are the valves too tight?

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Title: Re: Won't rev past 4000
Post by: 1975_Challenger_461 on June 01, 2014, 07:48:06 PM
Carb squirters working? At wot you should see fuel coming out the venturies.

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Title: Re: Won't rev past 4000
Post by: capogniracing on June 01, 2014, 08:18:48 PM
I can recheck valves but at same time if they were tight wouldn't it have a hard time idling. And squirters are opening at wot based on driveway dyno lol.


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Title: Re: Won't rev past 4000
Post by: capogniracing on June 01, 2014, 08:33:11 PM
It's a flat tappet cam with hyd lifters so zero valve lash and 1/2 turn is what there set at


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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on June 02, 2014, 09:05:40 AM
Did you buy these heads new and install them yourself? Just wondering if they had the springs swapped out or are dead, if they were used. I assumed they had the factory installed springs and were somewhat new... which would be more than good for the cam you're running.

Ever try that vacuum gauge to see how it reads?

9psi at wot... that is at the carb while running at the lake... not on the trailer?

Again... checked out the parts in the dizzy and wire going to it?

Dude... running out of external likely things.
Title: Won't rev past 4000
Post by: capogniracing on June 02, 2014, 09:27:27 AM
Ordered a better vacuum guage didn't get it before weekend. And yes 9 wot on lake. Went through all distributor wires and connections good. Bought boat with heads already on. I just ordered valve springs next day air so gonna try them out this weekend. I guess another 150 can't hurt right lol.


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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on June 02, 2014, 04:10:00 PM
Ordered a better vacuum guage didn't get it before weekend. And yes 9 wot on lake. Went through all distributor wires and connections good. Bought boat with heads already on. I just ordered valve springs next day air so gonna try them out this weekend. I guess another 150 can't hurt right lol.


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The vacuum gauge was so you'd know IF you had a spring problem or a valve seal problem or cam going south...

Dude... I hate to see you keep throwing parts and money at this thing without actually figuring out what it is. I mean eventually, you'll get it... but 35,929.41 dollars later... you'd be super bummed if turns out something obvious, but overlooked was the culprit.
Title: Re: Won't rev past 4000
Post by: capogniracing on June 02, 2014, 06:54:10 PM
I hope cam isn't going south only has 2 trips on it since I put it in. I should get my vacuum guage tomorrow so I can check numbers again. Wish I woulda got it before last lake trip.


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Title: Re: Won't rev past 4000
Post by: jimpen on June 02, 2014, 07:15:02 PM
Wow!!! 39,929.41 and you have not even got all your tow bill's yet.  Let me know if you need some help.
Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on June 02, 2014, 07:41:51 PM
Wow!!! 39,929.41 and you have not even got all your tow bill's yet.  Let me know if you need some help.


That number was just an estimate and may be a little high...  ;)
Title: Re: Won't rev past 4000
Post by: jimpen on June 02, 2014, 07:49:22 PM
I know him well..... I think you're in the ball park.
Title: Re: Won't rev past 4000
Post by: Ckaz21 on June 02, 2014, 08:02:07 PM
Was the cam broken in correctly and are you using a high zinc oil?


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Title: Won't rev past 4000
Post by: capogniracing on June 02, 2014, 10:59:48 PM
Ha lol penner I'm getting close to that lol. And cost you some brand new chrome headers too. And cam was broke in with zinc additive and very well lubed cam and lifters when installed. Did the 2000 rpm for 20 mins then rechecked valves and checked rocker movement. And also did prime oil system before I started with drill hooked to oil pump. Checked rocker movement again after first trip and were good. I have had 2 people pm me about valve springs, and honestly what I have into this boat if it's just another 100 bucks and might fix it then I'm ok with that. Springs are not hard to change out either if you have the right tools.  And at same time I'm getting to know whats exactly in the motor instead of guessing what it has.and looking at all my symptoms this is pretty high on the chart of what boat is doing.


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Title: Re: Won't rev past 4000
Post by: capogniracing on June 03, 2014, 05:53:18 AM
I know I haven't mention this but boat did sit for almost 5 years before I bought it. So this would also be another factor in maybe a couple weak valve springs.


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Title: Re: Won't rev past 4000
Post by: Six-Oh-Nine on June 03, 2014, 08:59:45 AM
Yeah... I didn't realize these heads were used with who knows how much use... let alone sat for a bunch of years. The springs that come with the heads would be fine... but not if you got some weak and/or dead players.
Title: Re: Won't rev past 4000
Post by: capogniracing on June 03, 2014, 09:25:23 AM
We will find out this weekend.


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Title: Re: Won't rev past 4000
Post by: capogniracing on June 08, 2014, 12:16:48 PM
Didn't change anything, ran like crap all weekend. It's time for a bbc have one on shelf so she's going in. Surgery starts Monday.


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Title: Re: Won't rev past 4000
Post by: Ckaz21 on June 08, 2014, 07:02:06 PM
I feel your pain man. I had the exact same thing happen last summer. Tried everything to fix it and nothing worked. Ended up buying all new parts and getting it rebuilt.

My hunch is that my cam went a little flat and my machinist told me I had a pitted intake valve. Could be either or but sometimes its worth it to drop a different engine in it before you waste all summer trying to figure it out.

Best of luck man


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Title: Won't rev past 4000
Post by: capogniracing on June 08, 2014, 07:17:21 PM
Ha thanks everyone for your help. ill be starting a new trend tomorrow for bbc swap. Wanna try and have her done in a couple months or less. And probably gonna be posting a bunch of small block stuff for sale tomorrow. Just incase any one is looking for something. Pm me. Needless to say whatever I can use for swap I will. So mainly just motor parts ect.


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Title: Re: Won't rev past 4000
Post by: capogniracing on June 08, 2014, 07:20:15 PM

Ha thanks everyone for your help. ill be starting a new trend tomorrow for bbc swap. Wanna try and have her done in a couple months or less. And probably gonna be posting a bunch of small block stuff for sale tomorrow. Just incase any one is looking for something. Pm me. Needless to say whatever I can use for swap I will. So mainly just motor parts ect.


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