Installed the HSR atop a set of Pro Topline heads.

With the car off, fuel pressure reads a steady 48.

With the engine running and the vac line plugged, FP is 48.

Plug in the vac line and the pressure drops to 40? Is that normal?

Is it when I accelerate that there is less vacuum, giving me more FP? I'm confused.



I've also got this almost backfire... hollow sound coming from the front of the engine it sounds like... now and then when I give it gas. Happens in park with the engine running. Let it run a bit then give it some gas and then there is POP like a reverse backfire?

I'm running at 8.5deg base timing, 24lb injectors, PROM tuned to 24lbinjectors....

Very confused. Can't floor it because it POPs and makes me worry!

 

yes,the drop of FP is correct for when u connect the vacuum line.

 

So when people say they are running at 43psi... is that the *maximum* or the vac line connected PSI?

IE GMHTP ran their HSR at 46psi..... ?

 

Usually they mean with vacuum line disconnected.....0 vacuum to AFPR.....

 

Okay, makes some more sense.

Upon more research it sounds like I'm getting a lean popping through the intake saying I need more fuel.

I can't get my spare chip to burn right now but I'll try my stock chip instead of the one I have burned for 24lb injectors. Richen things up a bit.