My car is running really well in the low rpms but it stops pulling around 4500 rpms. I don't know if my 4 barrel is opening and I am getting enough fuel pressure that it shouldn't do that. I have a question about the secondaries to. If you open the primary and secondaries at hand, while the car is idling, should fuel come out of your secondaries. When you open the primaries it come out in abundance, but when you open them both, because you can't just open the secondaries no fuel comes out. DO you have to be under load for the fuel to come out too, because I know with Vaccum secondaries they only work underload. The carb is a 4160 series 600CFM. Any help would be nice.

 

maybe you need a softer spring? you can usually feel the secondaries open



mike

 

Yea, when I had my 12a I had mechanical secondaries which you can really feel. I just think that maybe they are opening but not getting any fuel, and it leans out at top end..

 

I would check your spring for the opening RPM and rate. Also check your float level then go up two sizes in your secondaries if you really are lean. Air/ fuel gauges are great for working on your carb. I know the feeling on having vacum secondaries and the difference when you have mechanical secondaries. I had a holley 600 cfm double pumper mechanicl built for me by TY at www.TPCRacing.com and I now know that I sent hundreds of dollars chasing my tail when a great engineer shows you how to map a carb. Good luck