too much carburation

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23t
Posts: 3
Joined: Sun Jun 07, 2015 8:30 pm

too much carburation

#1 Post by 23t » Mon Jun 08, 2015 7:22 pm

I'm new to this site, and returning to drag racing after a long time away from it. A few years ago I bought super comp, tube chassis, 23 t fiberglass body. 400 Chevy bore to 406, Dart heads, roller cam, high comp pistons, running methanol. When I bought it, it had mechanical fuel injection with a Hilbert mechanical fuel pump. I left the pump but I put an Edelbrock tunnel ram with 2 quick fuel 650s on it. When I change the oil between race days, there is 6 qts of oil and 3 - 4 qts of Alky. I am considering going to an 850 cfm CARB on a Dart intake. I am just worried that I will mess up the performance on the car if I do. It runs 154 MPH at 8.92, which fits super comp pretty good. Then again, it may run better if I am over carbureted now. Any suggestions??

23t

bracketchev1221
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Joined: Fri Oct 11, 2013 7:59 pm
Location: Mountville PA

Re: too much carburation

#2 Post by bracketchev1221 » Tue Jun 09, 2015 6:54 am

I would definitely try to find the problem there. 3-4 qts of alcohol will eat the bearings right of the motor. Alcohol will wash the oil right out of where it has to be. The engine will only pull as much fuel out of the carbs as it needs. So to me it sounds like it is overflowing the vents or draining the carbs on shutdown.

23t
Posts: 3
Joined: Sun Jun 07, 2015 8:30 pm

Re: too much carburation

#3 Post by 23t » Tue Jun 09, 2015 9:27 am

I am running the Hilborn mechanical fuel pump, which was flow tested. I can't remember what the data was, but it was much higher than the crabs need. I put a pressure valve on and set it to about 13 pound (that's at about 1500 RPM, I don't have any idea what it would be at 6500 where the shift point is set). I Also used the pop off valve from the earlier fuel injection system with a return line to the fuel cell. Maybe I still have too much pressure and it is blowing the float needle off the seat and pushing fuel right thru. Is that possible? Do you have any idea what the pressure should be? Maybe it is all in the pump, a new electric pump would be easier to put on. Thanks for the input.

23t

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jmarkaudio
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Re: too much carburation

#4 Post by jmarkaudio » Thu Jun 25, 2015 1:02 pm

Put a large deadhead regulator on it, something like the Magnafuel large 4 port. Limit the pressure to 7 psi, 13 is way too much.
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23t
Posts: 3
Joined: Sun Jun 07, 2015 8:30 pm

Re: too much carburation

#5 Post by 23t » Fri Jun 26, 2015 8:20 pm

Thanks for the reply. I'll set the pressure back and try it this weekend.

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