formulaF302

help...running holly 5 1/2 lb electric fuel pumps in 502TRS Gen VI twins w/comp cams roller cams making about 500 hp in 86 Formula F302 with world products rectangular iron heads with big valves, MSD ignitions and stock intake manifolds.The carbs (performance series annular discharge) came with #85 jets all around.Using last years stock merc centerriser cast manifolds last year I ended up with #91 jets in primarys and #83 in secondarys and just running a little rich on rear 4 cylinders.I just switched to revolution marine exhausts and havnt run it yet, but found the rear 4 cylinders running REALLY rich while putting in new plugs.Is this a problem with float adjustment, the floor angle of the intake, or improper jetting? I also get a strong smell of gas after running awhile then sitting still about an hour..don't know if its a leaky fuel tank or not YET, but could it be fuel overflowing from improperly set float dripping into hot intake manifold when engine heat rises and evaporating after sitting still awhile? Its real strong the next day when I uncover it...but not noticible while running or when you first dock up....If floats...whats the correct method of float adjustment for this setup? While running?Pumps are wired in thru oil pressure switch for ground and key for pos..

blown1500

Hardly ever do I end up with more than 2 jet sizes change in a performance carb. The primary sounds way too rich and the secondary too lean. They should all be within 2 sizes of each other. It sounds like you have float or power valve problems or something. pm or post more info and we will try to help!!

dyno

I'm running 83's front and 90's in the back on my 454's....still a little rich.

Vinny P

There are just too many variables for anyone here to give you advise as to jet size. You need to start with setting your floats correctly. As far as jetting, you need to do plug checks. Don't forget about the power valve.

KAAMA

iTrader: (1)

At one time I had Holley HP-830's with annular discharge on each of my 540's that made 630hp @5400rpm. I was using #86 jets on all four corners and it still seemed to run a little on the rich side!

formulaF302

Ok...I got it running yesterday and still only got 4800 rpm out of it at 69 mph. Brought it back into the marina and pulled off the flame arresters. The port carb was all wet on top of the butterflys with gas. I pulled both carbs off and found the intake manifold on the port side puddled with raw gas in the little valleys in the casting so I mopped it up with rags before leaving and covered up the intake holes with rags. I'm going out shortly to see if there is a smell of gas in the bilge to eliminate a leaky fuel tank as the problem. If no smell...my problem would obviously be from heat rising up after shut down and expanding the gas from the bowls into the intake. I checked the float level of rear bowls of both carbs after pulling them off and they were right on the money...gas level right at the bottom of the screw hole. I'm gonna check the new plugs too in that I ran it for about 1/2 hour with new rear jets of #79. Please feel free to keep sending me any suggestions.....thanks... Glenn

formulaF302

pulled the plugs today...front 4 cylinders looked like no color at all....back 4 were all blackened out. What am I missing here? It almost looks like no matter what I do fuel is just pooling up in intake manifold and running to the rear. Am running Holly red marine fuel pumps without regulators. Someone else told me that you have to remove the fuel bowls to adjust the floats. Is this correct?

blown1500

You do not have to remove the bowls to adjust the fuel level.
Look for heat discoloration on the ground electrode-should be near the end of the bend on the ground electrtode(near the end, not the case of the plug). The power valve could be a problem or about 10,000 other things. pm if you like and I will call you or try to help any way I can.

formulaF302

We're not talking a little bit of discoloration here.....I'm talkin the entire plug turning black and carboned up like painted with black spray paint after about 20 minutes of hard running on new plugs. I'lm guessing its a float problem on both motors.....but on the rear 4 cylinders of each motor. Am I correct in guessing its the rear float (stock 502 dual plane manifolds) or is it from raw fuel running down towards the rear of the manifold from the front flots due to the drastic downward angle of the motors in an 86 Formula? The floats are currently set with the fuel level just below the screw hole while the engines are running. I'm assuming the holly 4150's w/830 annular discharges are blowout proof power valves since they are only a year old....I've had plenty of backfires before zeroing in my timing and swithching to MSD ignigtions, and numerous restarts with no chokes. Any help would be greatly appreciated. Will be back in town with email access again satuday night leaving the in laws place after tonight. thanks much blown 1500 or anybody else with suggestions.......PLEASE help.....Glenn

TomR

What is the model # on you carb??
The one I bought three years ago did not have power valve protection. I added it and have never had a problem tuning the carb.
My guess is you have blown out the power valves.