My neighbor runs a 70 SS 396. 12.5-1s, solid lift .629 lift cam, headers, Holley strip dominator, high stall converter and 3.73s. Engine has a nice idle to it. Feels real strong. He has a 950 Holley on it currently, but seems to run very rich at an idle. The rear bumper gets sooty and your eyes tear like crazy. I let me borrow my 750 double pumper and it seems to run much better with the smaller CFM. I have a feeling that the 750 might be too small for his application though. And the 950 seems too big to me. Any big block Chevy guys here that can enlighten me on what a 396 likes as far as CFM, what sort of jets/ power valve I should run etc? TIA
The stock L78 396s ran 780 Holleys, they could tach up about 7200 rpms. I think he would like an 850. It has alot of lift, he must have duration to match. How high does he rev? Around 850 should suit him, depending on how high he revs.
Oh yeah, thats enough compression, JEEZ. What kind of gas does he run and whats he run at the track ET wise?
He really doesnt take it to the track. Its more of a street car. He rarely pushes it. Just some light to light action if any. The engine saw 7k once when he raced my Stage 1. I pulled over and helped him put all the belts back on his carp In thinking about this, if the 750 runs that nice, I should just leave it on there for him. Im not sure he'll ever feel the difference.
He needs to put a .015 wire in the idle feed restrictor to eliminate the fat idle and mid range condition that most holley carbs have. I learned this first hand by using the innovate LM-1 air fuel ratio meter this summer, it is the only way to clean up the idle. You wil be amazed at what this does to the idle and crusie air fuel ratio. Most guys try and rejet to get it to lean out at idle. Look at an exploded view of a holley metering block to find out exactly where the brass idle feed restrictors are located (to hard to describe here), bend one end of the wire and the gasket will hold it from moving, you can always take it out with no permanent damage. .015 wire can be purchased at hobby shops for 3 bucks for 12 feet, you need 1 inch! Only put the wire in the primary metering block unless you have a four corner idle carb, then do both metering blocks
Hey thats a good tip! I never heard of that one before. Definitely worth a try. I'll take it apart this week. Just so I understand corectly, you just put a right angle bend on one end of the 1" wire?
If he never takes it to the strip and has only had it to 7 K once, you might as well leave the 750 for now. Thats a pretty serious combo for only street action though.
you wont even need 1 inch, the bend only stops it from going in to far, you will see how long it needs to be once you get the metering block apart. the gasket then goes on. You will be amazed at the hole shot improvement!
