I have a 350 with a holley 700cfm mech secondaries, and it seems that when i race with it, seems to loose fuel in the carb. Carb runs rich too. When racing the carb works fine, but after a lot of rounds it seems to loose fuel because the car just studers big time, and the rpms don't gain, changed the power valve to a 2.5. Could it be a problem with the fuel system because i took out the old 305tpi and put in a 350 carb, changed the fuel pump and regulated it to 6psi, not sure what the problem is thanks for your help.

 

I can't imagine you having a cam that justifies a 2.5 PV. What are the specs on your cam?

What are you using for fuel delivery? Pump? Regulator? Electric? Mechanical?

 

Originally posted by five7kid
I can't imagine you having a cam that justifies a 2.5 PV. What are the specs on your cam?

What are you using for fuel delivery? Pump? Regulator? Electric? Mechanical?

I run the 2.5 PV because with the stock one 6.5 it was always open just dumping fuel. Its a double pumper too. I use a stock electric 350 fuel pump, and a holley regulator. do u thing the PV is to much. the cam specs are at .050 lift 230/230 INT.480 EXH.480 from comp cams mostly for top end. thanks for your help.

 

That's not a good regulator to be using (assuming it's the typical dead-heading, non-return type Holley reg). Are you able to watch the fuel pressure while driving?

That cam shouldn't require anything less than a 6.5 PV, one would think.

 

The regulator has a return line and a built in guage so I can't see it inside the car. On the PV valve i know it sounds wierd but with my vaccum guage in the car at idle and in park it reads about 10 inchs, but when i put it into gear it drops to about 6inch to about 7 inch kind of hard to tell because the needle moves to much. Do u thing i should hook up a fuel guage so i could see it, what would be the best psi to run at WOT for a carb? And what do a suggest I use for a PV. Thanks

 

To the best of my knowledge, Holley only recently came out with a return style reg. Having "3 ports" does not a return style make. What p/n is the reg? Or, how much did you pay for it?

Getting the fuel gage up where you can see it, even just for the troubleshooting effort, is a good idea. Keep any fuel lines out of the passenger compartment for safety's sake (some guys tape the gage to the outside of the windshield while figuring things out).

After making sure you have at least 4 psi under all conditions, I'd start with a 6.5 PV, which is probably what your carb had in it to start. 10" vacuum sounds pretty low, even for that cam - check for vacuum leaks.

 

ok not sure on the p/n number i'll go find out, and start back with the 6.5PV, and check for vaccum leaks do u know the best way to find those. Thanks for your help.