You are correct, That's why i said, If you have 36* at wot.
You are correct, That's why i said, If you have 36* at wot.
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?
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.
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]. just kidding around.I hope this helps good luck with you boat and let us know how it turns out.
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.
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.
Have you checked the secondary throttle plate for adjustment? Are the slots in the plates equal with the front? If you have a adjustment screw adjust for a better idle.
Hows your fuel pump? Mechanical or electric? What is your fuel pressure at idle and at wide open.
I didnt see this info on your list. If its not your vacuum and your jetted right it could be a fuel pressure drop.
I just went through a simalar situation. For me it was a combo of things. I'm all good Now
Takin it home
PS:...Save yourself a lot of grief and install an o2 sensor. "Split Second" offers a kit with a series of colored lights that shows you exactly where your WOT mixture is. Not cheap, a couple of hundred and change, but a lot cheaper than a burned down engine. Once tuning is completed the header bung can be plugged to preserve the o2 sensor for future use....Check into "split Second" EGT kits.............
Last edited by Moneypit; 03-15-2009 at 07:52 AM.
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Sure, the timing could be tweaked better, but I think the other obvious issues are being overlooked.
1. It starts and idles great - initially. Carb is full of fuel.
2. He steps on it and it runs great - to full RPM, then drops down. Carb is emptied of fuel and is running on what little the pump is providing. Headers are glowing/plugs bright white - LEAN. Blue flames out of the pipes: What happens to a lean chamber?: The flame gets HOT and L-O-N-G.
3. He comes back down to idle and it won't idle. Carb is still empty and refilling.
Or check for obstructions in the fuel lines from the tank to the carb. A friend of mine had a fuel pressure issue a few months back. Anytime he'd get on it, fuel pressure would gradually drop to nothing and the motor would essentially run out of gas. Turned out there was a piece of the old tank level sender float that was deteriorating caught in the anti siphon valve on the tank. Got rid of the float and replaced it with a regular elbow and threaded hose fitting.
Wouldn't too little timing at wot do similar things(fuel still burning on the way out) as far as the headers glowing, and flames out the pipes?? Just throwing it out there. Maybe your dealing with more than 1 issue here Seth. Did it do this last season?
Another Hot Boat refugee
Combustion temp creates the glowing header effect. the fact that we are talking about a carb that was designed by Carter to give performance on a daily driver and feul economy should tell you something. Edelbrock took the old AFB carb,made it pretty and stamped the logo on! It is still a single bowl style carb and in a marine app will suck the bowl dry in a heart-beat. Just for a thought-lean runs a hotter exhaust temp than fat. Bud is sucking the bowl dry and creating a lean effect caused by excessive vacuum which will in turn lean the motor down and with the lack of food will die! Don't waste money on O-2 sensors just get a feul pressure gauge. IMLAO