SoCal Jet Boats
Tech Talk => Engine Mechanical / Electrical => Topic started by: 7hallet7 on June 25, 2013, 08:42:52 PM
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Well. Took the tub out the other day and this has been happening sense we got the boat done motor is a bbf 460 thats been re worked, around 650 hp. Runs good out of the hole untill it reaches 5k it doesn't die it just stops accelerating. It should turn around 6500, i talked to someone from scjb an we came to the conclusion that it needs bigger jets carb is holly 850 doubble pumper, not shure whats in it now. Could i just adjust it? Holly red fuel pump. Msd ignition, no rev limiter. Thanks guys, let me know what you think.
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Just because you think it should accelerate to 6500 RPM unfortunately don't mean squat.
There are so many factors that limit RPM on a jet that it is actually somewhat intimidating...
Valve timing, lift, duration.
Ignition timing
Carburetion
Synchronization and linkage
Impeller size
Loading of the pump
Ambient conditions.
If it was dark enough outside, the header color in your picture is pretty normal. Do you have an infra red thermometer?
GT
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Thanks for the reply, yeah i have a thermometer, what should the temp be ? And should it look like that with wet headers? We have an AA 9in impeller (im probably wrong on that) 10deg adv timing. I didn't realize that so many things could affect rpms. 10.5-1 compression. Valve size, motor runs great, it runs out at about 65mph. (Bear with me I'm only 16 trying to learn) i know all of the general stuff so if you say something i don't understand il just ask.
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Thanks for the reply, yeah i have a thermometer, what should the temp be ? And should it look like that with wet headers? We have an AA 9in impeller (im probably wrong on that) 10deg adv timing. I didn't realize that so many things could affect rpms. 10.5-1 compression. Valve size, motor runs great, it runs out at about 65mph. (Bear with me I'm only 16 trying to learn) i know all of the general stuff so if you say something i don't understand il just ask.
You are not going to pull 6500 rpm with 650 hp... Not ever.
Idle or base timing is 100% irrelevant. You need to know the timing at over 2500RPM, that is all that matters...
I think it's awesome that your only 16, I got my start in boats at 12, had a 15HP Hydroplane... :thumbup:
If you are looking to turn much over 5000 RPM, an impeller change will be in order, I would rather see you tune the engine for turning 5,200-5,500 though, I think you will be much happier with the end results...
Keep chipping away and asking questions and she'll come to you. :thumbup:
GT
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Keep chipping away and asking questions and she'll come to you. :thumbup:
GT
Yeah sometime :) but, what changes should i do to get it up around 5500 hopefully mostly adjustments, adjustments are free, free is good:)
Diffrent jetting? What should i be running for valve timing, im also getting alot of cavitation out of the hole, revs to about 5900 and goes absolutely nowhere if i punch it, is there a way around this or do i just have to roll into the throttle, maybe a different grate? But i feel like the grate doesent do much until the boats really moving. Thanks GT!!
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Yeah sometime :) but, what changes should i do to get it up around 5500 hopefully mostly adjustments, adjustments are free, free is good:)
With an assumed AA impeller, this will be your Achilles....
Diffrent jetting?
Sure..... Why not?
Seriously, think of tuning like this. Valve timing confirmed with a dial indicator, degree wheel and the cam card. Ignition timing at WOT confirmed, carburetor size confirmed as well as linkages, spark plug type and gap confirmed and documented, then and only then do you play with jetting, jetting is LAST...
What should i be running for valve timing, im also getting alot of cavitation out of the hole, revs to about 5900 and goes absolutely nowhere if i punch it, is there a way around this or do i just have to roll into the throttle, maybe a different grate?
As for the valve timing question, think advanced, the cam card will point you in the right direction, typically 4* advanced. Ignition timing starting point should be in the 34-36* BTDC at above 2500 RPM, this is just a guideline but should get you in the park.
Sounds as though you may have a leaking hand hole cover, shaft packing or a pump mount gasket. Sometimes they will blow a hole in the water and they are difficult to figure out.
But i feel like the grate doesent do much until the boats really moving.
very true, very correct, the loader does little to nothing at slow speeds.
Thanks GT!!
You are welcome.
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So would a good place to start be slightly tightening the gland packing, and seeing if it goes away at all, what about a worn wear ring? And could i pull the hand hole cover and seal it with silicone? And is the pump mount gasket where the pump bolts to the ride plate, that sounds like a pain in the arse to replace if need be. I have a water regulator i dont know if its possible for it to be sucking air in thru the bypass.
Oh yeah don't worry im not running out of questions :)
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So would a good place to start be slightly tightening the gland packing, and seeing if it goes away at all, what about a worn wear ring? And could i pull the hand hole cover and seal it with silicone? And is the pump mount gasket where the pump bolts to the ride plate, that sounds like a pain in the arse to replace if need be. I have a water regulator i dont know if its possible for it to be sucking air in thru the bypass.
The water regulator will be under positive pressure anytime the engine is running, so not likely..
As for the tightening of the packing land, if the packings are worn out, this will likely do nothing. Look for a drip about every two to five minutes while sitting in the water idling from the packing.
Wear rings are a funny thing... Typically they wont do what you explain as far as just a heavy cavitation out of the hole without letting the motor over rev while wide open, but plausible...
Pump mount gasket was just to point you in a direction... do not use silicone, a MOFO to get apart and the O-ring is cheap... ;)
Oh yeah don't worry im not running out of questions :)
Sort of figured..... ;D
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Pump mount gasket was just to point you in a direction... do not use silicone, a MOFO to get apart and the O-ring is cheap... ;)
Well thats just great istead of buying rewarders 50$ gasket set i decided to use 8$ sillicone, looks better works better i win, untill i have to take it apart, great.
Alright round 4? I think
Can i check and change valve timing with motor in?
Is it bad to adjust 0 lash valve play by feel?
And is it odd that one random time the boat got airborne and stalled dead in the water when we landed (started right up after)
Is a little blowby normal? Almost looks like a faint steam out of the breathers at idle, checked oil on the first break in run it had a white creamy look to it and im 99% shure its from the assembly lube. Never happened again no water in oil, i did have a problem with the cp performance water pump blockoff plate letting water into the crankcase from where the dip stick is, but i caught it beafore it caused damage. I now use a hardin marine block off plate (the cp performane plate came with the water regulator kit.
Cant really see the motor mounts but can see the front cover pretty good in this pic
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Well thats just great istead of buying rewarders 50$ gasket set i decided to use 8$ sillicone, looks better works better i win, untill i have to take it apart, great.
Actually, good call on the silicone as long as it is high temp for the exhaust, I seldom use exhaust gaskets on a boat.... ;)
Alright round 4? I think
Can i check and change valve timing with motor in?
Yes, you may need to use a harmonic balancer timing tape.
Is it bad to adjust 0 lash valve play by feel?
Yes, this depends on the camshaft and whether it is a solid roller, hydraulic roller or mechanical or hydraulic flat tappet....
And is it odd that one random time the boat got airborne and stalled dead in the water when we landed (started right up after)
I have done this a time or two and always felt that it was an electrical issue in the MSD 6AL, rev limiter issue.. Never proven it though.
Is a little blowby normal? Almost looks like a faint steam out of the breathers at idle, checked oil on the first break in run it had a white creamy look to it and im 99% shure its from the assembly lube. Never happened again no water in oil, i did have a problem with the cp performance water pump blockoff plate letting water into the crankcase from where the dip stick is, but i caught it beafore it caused damage. I now use a hardin marine block off plate (the cp performane plate came with the water regulator kit.
A little blow by is normal.
Cant really see the motor mounts but can see the front cover pretty good in this pic
Looks fine to me...
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I have a 460 and how we adjusted th timing is WOT across the lake and my buddy turned the distributor until It pinged and we backed it off a hair to get max performance.. my boat is a 77 Nordic hull Berkeley pump with an A impeller and a ss loader grate.. it turns about 5400 rpm and runs 70ish. Motor is basically stock with Dove heads ported and polished, RV cam, T-Ram with 850 holley. Good running motor.
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Have a 466 BBF with D3 ported heads, roller rockers, 850 holley dp and A impeller turning 52-5400 time set at 34... motor and pump are fresh rebuilds. I had a zerk added to the packing gland area to prolong them.(No drip)
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As for the tightening of the packing land, if the packings are worn out, this will likely do nothing. Look for a drip about every two to five minutes while sitting in the water idling from the packing.
2-5 minutes or seconds?
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2-5 minutes or seconds?
2-5 minutes for the Teflon packing, 1-2 minutes for the old style beeswax packing.
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2-5 minutes for the Teflon packing, 1-2 minutes for the old style beeswax packing.
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Well spank my ass and call me Sally. I have a gusher. I was told 5 seconds. That explains my cavitation problem along with the oring seal in the inspection cover, its there but so flat it does nothing.---OP sorry for the hi-jack. I owe GT Jets so many beers.....
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I twist my BBF all day long @ 7000 to 7200 rpm , c8ve heads ported polished flat top pistons , tunnel ram with 2 , 550's and a custom ground roller camshaft total seal rings (file fit) berk jg with s.s a impellar and I got probably around 5 to 550hp , it's a chemistry that was passed down from a old time ford builder and it works also I got 172# compression in each cylinder give or take 2#'s per cylinder.
Will take and post videos soon.
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Actually, good call on the silicone as long as it is high temp for the exhaust, I seldom use exhaust gaskets on a
Took the boat out today, ran perfect when i was cruseing at 3500 about 50 psi oil and 150temp tightend the packing a little and cavitation went away a little and eventuailly all gone, real fast out of the hole, still stops dead at 5k tried playing with the carb with no luck and reverted all o the changes we made, and last question can i pull the pump out without pulling the motor it looks like i can just un. Bolt the transom mounts and the ride plate, also if i have two diffrent loaders will a more aggressive one give me some more speed or just bog me down i have a berk 12-JC-A witch im guessing the -A means it originally came with an A impeller, if i were to get a diffrent pump what do you think would be a good one that my place diverter will bolt up to, the reasion i say this is because the one i have isint a split bowl and well i think is one of my problems, thanks again gt
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Took the boat out today, ran perfect when i was cruseing at 3500 about 50 psi oil and 150temp tightend the packing a little and cavitation went away a little and eventuailly all gone, real fast out of the hole, still stops dead at 5k tried playing with the carb with no luck and reverted all o the changes we made, and last question can i pull the pump out without pulling the motor it looks like i can just un. Bolt the transom mounts and the ride plate, also if i have two diffrent loaders will a more aggressive one give me some more speed or just bog me down i have a berk 12-JC-A witch im guessing the -A means it originally came with an A impeller, if i were to get a diffrent pump what do you think would be a good one that my place diverter will bolt up to, the reasion i say this is because the one i have isint a split bowl and well i think is one of my problems, thanks again gt
In all honesty you can technically pull the pump with the motor in place, but why not pull the eight bolts and three hoses and Yank the motor first? The amount of time and frustration it will save you is almost silly.
IMHO, you do not need a split bowl. Maybe just have your impeller cut to an AB by a reputable shop. But only AFTER you have exhausted everything else as far as troubleshooting. ;)
GT
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I think that is all you are going to get out of that thing. 5K RPM's. That sounds about normal. And yes it will just feel like it stops accelerating and just stays at 5k RPM's, welcome to the world of Jet pumps. I turned 6000 to 6100 all day long with a stainless "A" and a 8-71 EFI blown BBC/77 Nordic (scary ass ride at top end). As others have stated before, aint no way you are going to turn 6500 with that motor and impeller combination.
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Thanks guys, do you think if i add a droop i could get a couple mph?
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Thanks guys, do you think if i add a droop i could get a couple mph?
Nope. Probably make ride like crap too.
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Nope.
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Damnitt.
Anything i could do?
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Nope. Probably make ride like crap too.
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after talking to my dad he said the pump has a lot of work done 10in AA impeller, seems like I have more power than I thought to turn that thing checked cam and ignition timing needed adjusting and then played with jets 5400 rpm and 69mph good enough for me to leave it alone :D :D