SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: NoRestraint on September 14, 2011, 04:01:11 PM
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Ok so I was out at the lake today with my new fuel pump and bassett t-valve, everything works beautifully. However I am only reaching 3800 RPM at WOT and then I start to lose power. Any Ideas? I am running 9 lbs. for fuel, it's the holley black pump so fuel supply shouldn't be the issue. I don't know haha :banghead:
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how do the plugs look? hows your fuel pressure at WOT? i have a gauge on my fuel rail and i just sit back there while my gf floors the gogo pedal.
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I would check the jets on your secondarys/back bowel on holley. Sounds like a stuck jets or float in a back bowel. Just my newbie opinion.
:beer:
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ok if i were you i would look at what ive done, and then ask was it running right before i started???? if the answer is no . well ... look the first thing as a mechanic your taught is to see if someone has been in there before if not then move on. it could be a lot of things. well good luck.
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Ok it runs the same as when I got it pretty much. Here are some pictures of the plugs
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oh and who has the fastest reaction time to tell me what's wrong with this picture hahahah oh man :screwy:
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I would check the jets on your secondarys/back bowel on holley. Sounds like a stuck jets or float in a back bowel. Just my newbie opinion.
:beer:
This will be fun because I have never worked on a carb before :thumbup:
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ok it looks a little lean, so lets start with the carb, well the throttle linkage make sure that when you press the gas pedal all the way down that the carb opens all the way. start with the easy stuff first!!!!! oh what size carb do you have and do you know what jets you have??????
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Is it just me or is that 45 a little short?
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Is it just me or is that 45 a little short?
ding ding we have a winner haha, Hmm I'm not that big of a motor guy yet but aren't all the spark plugs supposed to be the same? :screwy:
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ok it looks a little lean, so lets start with the carb, well the throttle linkage make sure that when you press the gas pedal all the way down that the carb opens all the way. start with the easy stuff first!!!!! oh what size carb do you have and do you know what jets you have??????
it's a holley 4150 750 cfm. I think I have to continue this project tomorrow since I am running out of light. I'm gonna run up to kragen and at least throw some new plugs in. For an 86' 454 the ac delco plugs should be R44T with a .045 gap right?
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I don't think gap is the problem. Definately lean, lean, lean, although 1 plug looks kinda ok, and probably some timing issues. Yeah, get some decent MATCHING plugs......
I didn't quite get your first post. It's spinning to 3800 rpm max, and for how long before it seems to "lose power" and rpms drop? What impeller is in there, and what pump, for that matter. Could be important.
Personally, I wouldn't run anything under an 850 in any BB jet boat if I could help it. But at 3800 RPM on a 454, you certainly aren't running out of carb. And that is where I'd be looking. As said, secondaries not opening, severe jetting issues, as lean as you are, and the very low rpm, I'd be swapping carbs. But I have a few extra around here to do that with. At the very least, run it, then look down it's throat, not running, and open the thing up manually and see if the squirters are working on all four corners at least, but you're look at a carb overhaul at minimum.
Ray
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I have a bbc 454 in my boat and I run the ac delco R43T and they work fine.
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I don't think gap is the problem. Definately lean, lean, lean, although 1 plug looks kinda ok, and probably some timing issues. Yeah, get some decent MATCHING plugs......
I didn't quite get your first post. It's spinning to 3800 rpm max, and for how long before it seems to "lose power" and rpms drop? What impeller is in there, and what pump, for that matter. Could be important.
Personally, I wouldn't run anything under an 850 in any BB jet boat if I could help it. But at 3800 RPM on a 454, you certainly aren't running out of carb. And that is where I'd be looking. As said, secondaries not opening, severe jetting issues, as lean as you are, and the very low rpm, I'd be swapping carbs. But I have a few extra around here to do that with. At the very least, run it, then look down it's throat, not running, and open the thing up manually and see if the squirters are working on all four corners at least, but you're look at a carb overhaul at minimum.
Ray
Thanks Ray, so do you thing I should start with timing?
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I have a bbc 454 in my boat and I run the ac delco R43T and they work fine.
Thank you sir, wasn't sure
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Your list of things to check is a short one.....
1- look for some ski ropes, duct tape, baseball cap, plus size woman's bra etc in the pump or on the pump shaft.
2- Check the timing at above 2500 RPM, I disagree with the lean statements at this time, did you hear a "popping" at WOT?
3- How fast do you feel the boat was going? GPS? are you sure the tach is running right? (be surprised how many times this is the issue).
4- Does the throttle linkage go WFO? Not with your hand at the carburetor, but with the foot on the long skinny pedal.... I have seen some carburetor installs have a linkage clearance issue with some cable mount brackets.
To add, you did not mention what ignition you are running, this has a gigantic influence on what the plug gap should be..... ;)
GT
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Thanks Ray, so do you thing I should start with timing?
No, I think the carb should come off and be carefully gone through and rebuilt, myself. But I'm not there looking at it either to know for sure that's the issue. But I HAVE seen plugs look like that, that weren't really lean, it was all in timing. My own boat was one. But you're only getting 3800 RPM (Provided the tach is RIGHT), and as lean as the plugs look to me, which would indicate to ME, anyway, the secondaries on your 4150 aren't even in the same playground when the rest of the boat has already picked teams and started the game. Could be something else, but that's where I'd look first.
Ray
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Also sorta slipped my mind, be careful with plug selection, it depends what heads you have, if you run a long reach plug where a short reach is needed, it can get expensive in a hurry....
GT
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Ok I got my pitot tube today so we will know how fast I am going tomorrow, put new plugs in, and I guess I need to go buy a timing gun :D
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good luck tomorrow, try to keep a running tab on how it runs not just at wot but at all speeds you know how it starts cold and hot how it idels, 1/4 throttle 1/2 throttle 3/4 and full. hell bring a note pad.these are all things that will help you. have fun.
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interested in what the problem could be. i had like a 63/71 set of jets in my 650 carb and it ran awesome at WOT still... but it sputtered in between and my plugs looked lean. i changed to 75/80 and now it runs awesome and the plugs have a nice little brown around around the insulators like they should.... is it a vac secondary carb?? do you even feel the secondaries kick in at all? mine makes a very audible "weeeee" sound...
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interested in what the problem could be. i had like a 63/71 set of jets in my 650 carb and it ran awesome at WOT still... but it sputtered in between and my plugs looked lean. i changed to 75/80 and now it runs awesome and the plugs have a nice little brown around around the insulators like they should.... is it a vac secondary carb?? do you even feel the secondaries kick in at all? mine makes a very audible "weeeee" sound...
Your "weeeeeeeee" sound is likely a vacuum leak in the secondary diaphragm brother............shouldn't hear anything other than a little more "whoosh" sounds than normal if the scoop is facing forward. Otherwise, probably wouldn't even hear that.
Ray
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Your "weeeeeeeee" sound is likely a vacuum leak in the secondary diaphragm brother............shouldn't hear anything other than a little more "whoosh" sounds than normal if the scoop is facing forward. Otherwise, probably wouldn't even hear that.
Ray
new vac diaphragm. i dunno... weee woosh, its only when they open up that i hear it and then it goes away once they're open.
my point is that when my carb was jetted really lean at least it would run and it ran fine at idle and WOT and it stumbled inbetween. i still hit 5k even with those small jets.
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Try the float levels, or maybe even a dirty fuel filter.
The beav
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new vac diaphragm. i dunno... weee woosh, its only when they open up that i hear it and then it goes away once they're open.
my point is that when my carb was jetted really lean at least it would run and it ran fine at idle and WOT and it stumbled inbetween. i still hit 5k even with those small jets.
Perfect example. The diaphragm is not leaking, but the housing is. Shoulda been more specific on my part. Working for now, but just so you know next year when you change the diaphragm, you got a warped cover or something that should be stoned out, just sayin.
I'm still thinking this poor guys secondaries are not even thinking about coming to the party.............yeah, a 4150 Mechanical, and the butterflies are opening, but no fuel to support the secondaries???? Ceramic filter in the bowl clogged? metering block clogged up? could be many things, but I think that carb needs to come apart.
Ray
Ray
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Perfect example. The diaphragm is not leaking, but the housing is. Shoulda been more specific on my part. Working for now, but just so you know next year when you change the diaphragm, you got a warped cover or something that should be stoned out, just sayin.
I'm still thinking this poor guys secondaries are not even thinking about coming to the party.............yeah, a 4150 Mechanical, and the butterflies are opening, but no fuel to support the secondaries???? Ceramic filter in the bowl clogged? metering block clogged up? could be many things, but I think that carb needs to come apart.
Ray
Ray
Just to say this out loud....No way in hell you know that from your desk....No way. Been a mechanic for going on 25 years and I call BS..
;)
GT
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Been waiting to see if it was the diaphram or secondaries just stuck......
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Well we made it up to big bear this morning and decided to run the boat tomorrow and relax today. I am getting the woosh sound at wot from what I remember and if I'm having lean issues they should be amplified up here so it might be a non tuning weekend I'll let you guys know tomorrow. And I'll definitely take some notes down, he'll I should be able to take video with this damn smart phone
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I am here: http://maps.google.com/maps?ll=34.229044,-116.841926
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But I'm leaning towards the secondaries not workin, how the hell would I test them? They are vacuum
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I am here: http://maps.google.com/maps?ll=34.229409,-116.842106
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Ok guys now i have no idea. Just got off the water and ran like shit as usual at 3500 wot when I pulled it out I wanted to get the water out so I tapped it a few times and it hit 5200. What the hell? Haha so maybe it's a pump issue or some crap escaped from the fuel lines. While out on the water it did shudder a bit on take off then smooth out. Any ideas?
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I am here: http://maps.google.com/maps?ll=34.229035,-116.841996
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Thats normal NoRestraint, it will rev to whatever when its out of the water, no load on the motor. Kinda like revving a car in neutral.
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Ok guys now i have no idea. Just got off the water and ran like shit as usual at 3500 wot when I pulled it out I wanted to get the water out so I tapped it a few times and it hit 5200. What the hell? Haha so maybe it's a pump issue or some crap escaped from the fuel lines. While out on the water it did shudder a bit on take off then smooth out. Any ideas?
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I am here: http://maps.google.com/maps?ll=34.229035,-116.841996 (http://maps.google.com/maps?ll=34.229035,-116.841996)
Free spin is a whole lot different than pumping a ton of water...Out of the water the engine does little/no work.
Testing the secondaries is quite simple, first, remove the flame arrestor/scoop/air cleaner and have someone floor the gas pedal with the engine off (make sure the choke is off if it has one), then look to see if the linkage will "allow" the secondaries to open (normally in the rear of the carburetor).
Once this has been confirmed, find the large dash pot on the side of the carb and push up on it with a finger, the secondaries should open quite easily. If not, bingo! If it does, there are four screws on the top of the dash pot, sometimes one will be hard to get to and the pot needs to be removed from the side of the carb with the two screws into the barrel of the carb body.
Inside the dash pot should be a yellow spring and a rubber diaphragm, chances are this diaphragm could be damaged, cracked or have a hole in it. It is replaceable and available separately as a repair kit....If the spring is any other color than yellow you may want to pick that up too....The yellow if memory serves is the lightest spring....And in my opinion the one you should be running...
Good hunting
GT
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Thanks proposes and Gt. I will have a look at the secondary deal tomorrow and let you know. I appreciate the help
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I am here: http://maps.google.com/maps?ll=34.229307,-116.841813
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So can I rule out a timing issue?
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I am here: http://maps.google.com/maps?ll=34.229310,-116.842015
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At this point it would be a good idea to go ahead and give everything a once over. Cant hurt to check it out, just to be sure.
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So can I rule out a timing issue?
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I am here: http://maps.google.com/maps?ll=34.229310,-116.842015 (http://maps.google.com/maps?ll=34.229310,-116.842015)
What proppy said...All needs to work together, get the tune dialed in so you know what it's "not"....
GT
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will do :thumbup:
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My guess would be spark plug wires! They generally only arc against each other when under a load. Cheap and easy , one of the first things i would check if I was going to start ruling things out.
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where u located? could help u out if im close im in perris
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Thanks Hondo I'm about an hour away over in Montrose. So I pulled the dash pot apart and the yellow spring is in there, should I replace it with a bigger one? I read on Holley's website that it will bog at wot if the secondaries open too early...And thanks Marc I'll check up on the wires
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Thanks Hondo I'm about an hour away over in Montrose. So I pulled the dash pot apart and the yellow spring is in there, should I replace it with a bigger one? I read on Holley's website that it will bog at wot if the secondaries open too early...And thanks Marc I'll check up on the wires
Nope.....Use the yellow one...IMHO it is the correct spring. Does the linkage work?
GT
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Will do, yes. So my mechanic friend helped me out today. The timing was at about 30* btdc and the vacuum advance was always engaged even at idle so we pluged the hose to the distributor and retarded to 12* gonna see how she runs. Why the hell would my motor run half way decent at 30* btdc?
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I am here: http://maps.google.com/maps?ll=34.216963,-118.233313
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I'm retarded.....
Double posted somehow vvvvvvvvvvvv :screwy:
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Will do, yes. So my mechanic friend helped me out today. The timing was at about 30* btdc and the vacuum advance was always engaged even at idle so we pluged the hose to the distributor and retarded to 12* gonna see how she runs. Why the hell would my motor run half way decent at 30* btdc?
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I am here: http://maps.google.com/maps?ll=34.216963,-118.233313 (http://maps.google.com/maps?ll=34.216963,-118.233313)
What RPM was the timing at 30*? It realistically should be at approx.34-36* at above 2500 RPM, at idle it will probably work out to be about 20* (+/- 5*).
This is important because the vacuum advance allowed the timing to drop back down at WOT because of the lack of a vacuum signal (jet pumps use up all the torque a motor can muster). You do not need to plug the port on the distributor, it does not go anywhere, but the port on the carburetor will need blocked. Basically your timing advance was working backward for the most part. Possibly a huge part of your problem.
Keep in mind that timing marks should always be verified that they are actually at 0* TDC on cylinder 1, sometimes harmonic balancers can be off by quite a bit...
Good luck, now we're getting somewhere... :thumbup:
GT
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Thanks GT, what I meant to say is we blocked off the carb. I'm not exactly sure what the timing was at idle because my numbers on that tooth lookin thing (what's it called?) only go to 16 below and 4 advance so 30 was kind of a guess. and that was at idle about 800 rpm. Do I have to pull the head off to see if the harmonic balancer is actually reading at tdc or is there another way?
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Thanks GT, what I meant to say is we blocked off the carb. I'm not exactly sure what the timing was at idle because my numbers on that tooth lookin thing (what's it called?) only go to 16 below and 4 advance so 30 was kind of a guess. and that was at idle about 800 rpm. Do I have to pull the head off to see if the harmonic balancer is actually reading at tdc or is there another way?
take out plug #1 and crank it over with the starter. put your finger over the hole. TDC on the compression stroke will blow air out of the spark plug hole with your finger over it. this way you know you're close. i took a zip tie (something that isnt hard, or will damage anything if it breaks off in the motor) and poked it into the hole and watched while turning the motor over by hand when the piston was at its very top before going down again. then i verified the balancer timing mark. mine was a little off so i painted a line where it actually was.
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Thanks GT, what I meant to say is we blocked off the carb. I'm not exactly sure what the timing was at idle because my numbers on that tooth lookin thing (what's it called?) only go to 16 below and 4 advance so 30 was kind of a guess. and that was at idle about 800 rpm. Do I have to pull the head off to see if the harmonic balancer is actually reading at tdc or is there another way?
No need to pull anything apart to verify TDC....
Pull the number one plug, use a wooden dowel or a wood pencil and use a wrench/socket on the harmonic balancer bolt to turn the engine until the hash mark on the balancer starts coming up on TDC, the check where the piston is using the "stick" through the spark plug hole. keep moving the crank forward (slowly) until the "stick" stops moving upward....That will get you in the park. you gon move things back and forth until you get a good feel for where the top is, then you can compare that info to where the mark is on the tab....Use White Out or whatever to make a new mark if is way off.
You can do the timing at 2500 RPM a few different ways, the best is a timing tape on the balancer, the next best is and advancing timing light, the redneck is to use an angle finder or degree wheel to make a new mark or marks where you want to be, I normally make a 32*, 34*, 36* and a 38* mark on the balancer...It easy and free..... :thumbup:
And kaOtyk, it don't necessarily need to be on the compression stroke just to find TDC... ;)
GT
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Thanks guys I'll give it a shot