Carter YF carbs...How much fuel pressure?

My '49 runs a 261 with dual Carter YF's .I have had a problem with vapor lock on hot days so I am in the process of installing an electric fuel pump .The pump is pre-set at the factory at 5 psi and I am installing a regulator that goes down to 4 1/2 psi. Is that too much pressure for my YF's ?
Thanks ! PAUL

 

that should work.but I turn mine down to 1.5 lbs. Got that tip from ****ster here on the hamb. He will sell you the right regulator if you cant find one

 

I tried it at 4 1/2 psi and it was too much ....I have a different regulator on the way.PAUL

 

try to use some spacers to prevent the heat from boiling the carb
have the same problem on v8 with edelbrocks

 

I always ran a stock fuel pump and never had any problems. If you go to a electric pump, just set the regulator to whatever a stock pump puts out.

 

Depends!

If you are using Carter YF's which were designed for Chevrolet, and have the stock size spring-loaded fuel valves, then 3 1/2 to 4 1/2 pounds. Less than 3 could starve the engine, more than 5 could cause flooding.

If you have other than the above, seat-of-the-pants testing is in order.

Jon.

 

My carbs are 964 yfs and just by letting the pump run a few seconds I managed to screw up my carbs..I must have had some filings go through because fuel won't stop flowing from the accelerator pump hole on one carb no matter what the pressure is set at .I got the front one down to a drip after tapping it but not the rear.I pulled the top off of the rear and adjusted the float down a little but then it got worse..Time to pull them both apart and rebuild them..........

 

O.K. Now I'm frustrated! Car runs great for about 10 miles and then vapor lock sets in . Mainly at idle. I get back from a drive and pressure gauge says 0 .I insulated the fuel lines from back to front .Same thing. There is 1/4 tank of 10% ethanol in it, the rest is ethanol free. I'm going to drain the tank and add 100% pure gas and see what happens ...This car has had this problem since the original engine was in it .Gas tank was replaced when I first got it,as were the fuel lines (2x) . I'm running out of Ideas.....Can anybody help?

 

drilled a small hole in the cap, I can let it idle and watch fuel pressure drop......

 

well, lets go back to the stock type set up and double check everything:

filter? plugged?
bake lite insulators?
if you have heat, take it off
stock fuel pump? work correctly?
fuel lines routed correctly? no xs heat? no cracked lines?
correct gas tank cap?

does this help?

 

I got my handy dandy infared thermometer out and checked everything from front to back . I gain 10-15 degrees from the exhaust pipe running next to the gas tank. S0 I'll get some exhaust wrap and fix that. I found that the rear carb base gets up to 300 degrees and the front only gets to 200 .Both carb bodies stay around 170 and the rest of the fuel line is 140 -170. Why would one carb base get so much hotter than the other ??? I have an offy intake with water heat and insulators under both carbs.... PAUL

 

I went through this on my 54 Chevy. I plumbed a return back to the tank and problem solved. I also put a electric pump in but haven't had to use it even on 90+ degree days. Good luck