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Or Seth, either one
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Discussion Starter #1 (Edited)
When I first put it in the water I step on the gas a couple times and she fires right up and happily idles as low as 600rpm (wont hold that setting in gear though), but I usually set it about 900-1000 which put the idle at 700 in gear. When I'm cruising or wot for a while and come back down to idle, it stalls and wont idle at all. Not sure if it's a temperature issue or not. Also, on long cruises at night the headers glow bright orange, even at part throttle.

I don't want to steer your responses too much, but I'm thinking it's just way too rich or timing is retarded (slipped outer ring on the balancer)

18' v-drive, 396 BBC, +/- 10:1 cr, performer intake, Edelbrock carb (1407) w/mechanical choke, 2" "open" carb spacer, vacuum advance HEI distributer (hooked up to manifold vacuum) timing is set at 36*, plugs gapped at 0.040, 160* thermostat, 049 heads, unknown mechanical cam.

OH! one other thing I notice that the first time I go WOT rpm's go up to about 4700 rpm, but as I stay on it it goes down to about 4300, usually within a few minutes.

So, where do you think I should start? What's your take?
 

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I would first check for a vacuum leak around the carb or spacer. exhaust gas temp should be about 1250deg on gas. at wot. IMO. That is not hot enough to turn the headers red. I have had trouble getting those carbs to make power over 5000rpm. But it sounds to me like it's going lean and then noses over. Check that, then put a new set of plugs in it and make a short run at wot. About a half mile or so. the plugs should have a brownish color to them. and all look about the same. If all else fails check fuel psi 7lbs wot, if that's ok then swap carbs. Hope this helps.
J
 

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mo balls than $cents$
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When I first put it in the water I step on the gas a couple times and she fires right up and happily idles as low as 600rpm (wont hold that setting in gear though), but I usually set it about 900-1000 which put the idle at 700 in gear. When I'm cruising or wot for a while and come back down to idle, it stalls and wont idle at all. Not sure if it's a temperature issue or not. Also, on long cruises at night the headers glow bright orange, even at part throttle.

I don't want to steer your responses too much, but I'm thinking it's just way too rich or timing is retarded (slipped outer ring on the balancer)

18' v-drive, 396 BBC, +/- 10:1 cr, performer intake, Edelbrock carb (1407) w/mechanical choke, 2" "open" carb spacer, vacuum advance HEI distributer (hooked up to manifold vacuum) timing is set at 36*, plugs gapped at 0.040, 160* thermostat, 049 heads, unknown mechanical cam.

OH! one other thing I notice that the first time I go WOT rpm's go up to about 4700 rpm, but as I stay on it it goes down to about 4300, usually within a few minutes.

So, where do you think I should start? What's your take?
timing is set to 36, then you gave it manifold vaccum???? if ya did, that's your issue. hope ya didn't melt any pistons. base timing for a hei otta be around 8 degrees btdc, the mechanical advance part will carry it into the 20's, then the vaccum advance will carry it on up from there. headers glowing is a sure sign of a lean issue, wether that's a fuel issue or ignition.i'd wanna see what max advance actually was while the motor is working hard.

ditch the vaccum hose to the intake , use the mechanical advance built into most hei dizzys instead. give it max 36, no more.
 

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Or Seth, either one
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Discussion Starter #4 (Edited)
timing is set to 36, then you gave it manifold vaccum???? if ya did, that's your issue. hope ya didn't melt any pistons. base timing for a hei otta be around 8 degrees btdc, the mechanical advance part will carry it into the 20's, then the vaccum advance will carry it on up from there. headers glowing is a sure sign of a lean issue, wether that's a fuel issue or ignition.i'd wanna see what max advance actually was while the motor is working hard.

ditch the vaccum hose to the intake , use the mechanical advance built into most hei dizzys instead. give it max 36, no more.
Clarification: I set timing at 36* at 5000rpm with the vac advance disconnected.

And... the headers glow all the way from the flange to the collector. You don't see it during daylight though, only at night. And you can see blue flames out the end :) Doesn't make sense that it would be lean, but if that's the concenses...

OH! the plugs look clean, porcelain is white. They have about 4 days run time on them and they're still pretty darn white.
 

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mo balls than $cents$
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Clarification: I set timing at 36* at 5000rpm with the vac advance disconnected.

And... the headers glow all the way from the flange to the collector. You don't see it durring daylight though, only at night.
yep, your giving it wayyyyyy too much timing advance. run it without the hose!!! plug em up and never think about a vaccum advance on a boat again!:D

change those plugs too while you at it, they've been detonated and you don't want that insulator in the cylinder!!
 

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mo balls than $cents$
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Good point, I missed that intake vacuum part. a $4.99 timing tape is never a bad idea.
timing tapes are great as long as they're installed when the motor was tdc'd, otherwise you'd be trusting that the balancer/timing tab are correct and that's rarely the case, at least i've never seen it perfect before. i've actually had to pull off the head to tdc a friends boat that i knew wasn't right, his marks were off 13degrees:)sphss
 

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mo balls than $cents$
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So is the advance hose off or on?
glowing headers answer that for ya, it was on:D

set the timing at 36 max, if you have 4 corner idle on the carb, screw them all in and back em out 1 1/2 turn just as a base tune-up. that should get ya close on idle mixture, enough to play with it without the motor loading up and die'n or leaning out.
 

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Or Seth, either one
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Discussion Starter #10
Good point, I missed that intake vacuum part. a $4.99 timing tape is never a bad idea.
Have the tape on there, it is the only way to go without dropping coin on a fancy dampner or dial back timing light

yep, your giving it wayyyyyy too much timing advance. run it without the hose!!! plug em up and never think about a vaccum advance on a boat again!:D

change those plugs too while you at it, they've been detonated and you don't want that insulator in the cylinder!!
Sorry, I think I was editing my post above to add a few details when you posted this...

Anyway, it's not detonating. I don't want to get in to the whole vac advance discussion again, but at WOT there is not vacuum and therefor no advance other than centrifugal advance, and the extra advance at idle is "supposed" to give a better idle.

I really don't think it's too advanced or too lean, with flames out the tail pipe... I've been wrong many times before though.

Either way, I'm not understanding how either of those would affect the idle the way what ever it is does.
 

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mo balls than $cents$
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when i drop in a fresh motor, the 1st thing i worry about is setting the timing right(after oil pressure is checked of course), from that i move to idle mixture. you can advance timing and make the idle move up, you can retard timing and it'll drop rpms.

say you're timing is high and you carb is lean at on the idle circuits, well your idle with the pump loaded will be shit.

fyi, unless you have a perfectly working motor, your advance port on your carb will still have vaccum on it at wot. i could be wrong but a vaccum gauge and a heavy foot would clear that up for ya;):D check it just for shits and giggles man.
 

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Clarification: I set timing at 36* at 5000rpm with the vac advance disconnected.

And... the headers glow all the way from the flange to the collector. You don't see it during daylight though, only at night. And you can see blue flames out the end :) Doesn't make sense that it would be lean, but if that's the concenses...

OH! the plugs look clean, porcelain is white. They have about 4 days run time on them and they're still pretty darn white.
If the plugs are still that clean , sounds like your real lean . Unhook the hose to the advance and set total timing at 36degrees and then see what it is at idle you may have to much mechanical advance in that dizzy. Then check into the lean condition, back the idle mixture screws out a half turn and jet that baby up a few jet sizes and see what the plugs look like after a 1/2 mile run.
 

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If it was rich, you would be trailing black smoke. The plugs would be black.
If you have 36*at wot. White plugs after four days of running. RPMs that run up to 4700 then fall off to 4300. and headers turning red. Poor idle. I keep going to a vacuum leak.
 

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mo balls than $cents$
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If it was rich, you would be trailing black smoke. The plugs would be black.
If you have 36*at wot. White plugs after four days of running. RPMs that run up to 4700 then fall off to 4300. and headers turning red. Poor idle. I keep going to a vacuum leak.
its possible, but he's feeding it too much advance if its the basic ole hei dizzy. i've seen them vaccum advance at wot with my own eyes watching the lite and timing marks. my dominator 1050hp on a big compression motor at 6800rpms would still show some vaccuum under the carb. as blower motor will also see vaccum under the carb if the carbs are a bit too small.
 

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Or Seth, either one
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Discussion Starter #16 (Edited)
Anyone else???

If not, I'll buy a lock out plate and a jetting kit to fatten her up next week.

Too lean doesn't make sense to me because it idles great when it's cold when it should need a richer a/f ratio.

Maybe I'm too lean on the idle circuit but too rich on wot??? Sht, I don't know. that's why I'm asking you guys.

Maybe it is a vacuum leak? Really, any one else?
 

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Are the plugs too hot a range? Is the water temp ok, water is flowing correctly? enough fuel presure? Also to check plugs for color the fuel today is tough to read add a little octane booster and the plugs will turn color.
Hook up a vacumn guage and watch to see whats going on, just a thought.
 

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more info

well tell us the history of the boat when did this problem start? did you do something new to boat or engine?when and where did you last buy gas for it the last too times out?have you checked the fuel for water or dirt? have you checked fuel psi at all speeds?do you have too tanks and dose it run the same on both?all power and ground cabels are tight and clean? is the carb mounted level?you say you have spacer is gasket installed the right way?the engine timing is almost every thing for a good idle and top end you need to recheck the timing and should try to set it at 8-9 degrees btdc while tryen to get the idle to come down to 750 rpm.becouse if your timing is to far advanced like we think it is you are going to need to slowly bring it down to 8 degrees while aujusting the idle speed on the carb at kind of the same time becouse it may want to die while bringing the timing down.and you should need your air mixtures turned out to 1 1/4 as a starting point.then once you do set the timing you will want to rev the engine up to as hi as 3400 rpm to make shur it is advancing and see what it gose to.if i remember right it should go to the hi 20's or low 30's witch should be ok to run.imo seting the total advance at 36 degrees at 5000 rpm is way to hi of a rpm to be doing that.they call that floting them valves i believe. you should only need to go as hi as 3400.also i say this becouse when i watch the timing with a light you can see the total advanced timing start to drop a few degrees at around the top end.it dose sound like it is running lean and lean is heat and run rich is cooler.once you get all this checked or fixed then the next step might be vacuum or rejet the carb.imo the guys that where helping you too day where on the right track.impatient 1 dose give good info and knows his stuff [for a gm teck].:p:):D:)devil:)hand;) just kidding around.I hope this helps good luck with you boat and let us know how it turns out.
 

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Start with known issues first.

Your timing is screwed up.

Setting total timing with vac advance unit hooked up will in essence reduce the timing at WOT by the amt the vacuum daspot adds. Say you have a 10° dashpot. AT WOT (no, too very little intake vacuum) your 36° is now 26°. If you happen to have a 20° dashpot, then total at WOT will be 16°.

Retarded timing will cause your headers to glow red.

This is a boat (ie: load) so remove your vacuum advance. Set your total timing back to your 36, if this is the # you are shooting for. Remember, this distributor had advance springs/weights. So keep reving the motor until the advance stops. This is the rpm you use to set total.

BTW#1 : this vac adnace hook-up and setting your timing with it hooked up, can/will reduce your initial timing (proper initial timing is needed for good idle)as the idle rpm comes down.

BTW #2: you did not state if your headers are dry or wet injected. if they are dry, they will turn red after some time because of all the exhaust heat from being under load at rpm.

BTW #3: Impossible to tune a carb with improper engine timing. Thus, you must get timing done correct before your dig into the carb.

Issues like this, I always suggest to check engine compression first. A wounded motor can not be 'tuned' to make it run good.

Then, set your timing correctly.

Then, hook up a fuel psi gauge and take boat for a run. If it runs good and fuel psi is good and plugs look good, your done other than maybe fine tuning for best performance.

If boat runs like crap and fuel psi is down, it's fuel system upgrade time.

if boat runs like crap and fuel psi is okay, then it's time to go thru (truly inspect and fix if need be) ignition system first and then carb.
 

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Anyone else???

If not, I'll buy a lock out plate and a jetting kit to fatten her up next week.

Too lean doesn't make sense to me because it idles great when it's cold when it should need a richer a/f ratio.

Maybe I'm too lean on the idle circuit but too rich on wot??? Sht, I don't know. that's why I'm asking you guys.

Maybe it is a vacuum leak? Really, any one else?

Idle, cruise, and WOT are seperate parts of the carb's metering system. Some interact with the other.

Having one 'rich' doesn't mean the other 'is rich.' Same with 'lean' of course.

I'm not an Edelbrock fan for hp motors, thus I have no real knowledge of them other than for stock type motors, and thus can't help with your's. Sorry.
 
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