Here's some pics of the carb and the 1"spacer I have. It has option of 4 holes vs wide open. Which should I go with considering the split edelbrock intake and why? Please explain? I will be driving probably no more than 2500-3000 rpm 90% of the time with occasional 4-5k rpm fun moments. Ty
The way I learned it, the open square is for single plane intakes and the 4 hole is for dual plane intakes. Why I am not sure but it has to do with making the air flow smoother for better low rpm response.
Thats the way I learned also but trial and error might not hurt because it all has to do with the gas be atomized or something like that
Based on your described performance requirements, it probably won't made any difference. My particular 302 combination worked best with a Performer RPM manifold and the open spacer. My findings are from actual 1/4 mile testing with RPMs reaching 6,800. You make some great videos! I like your valve covers, they sure make that 302 look a lot larger.
You'd probably be best to not use an aluminum spacer at all. A phenolic spacer would help keep the carb cool and less chance of vapor lock.
I agree with greasemonkey, go with a phenolic spacer. They will have less heat transfer and will decrease the chance of vapor lock. You will only need about a 1/2" spacer, you can go up to a 1" but you really don't need it. Also like the others have stated open vs 4 holes spacers do have a difference in single vs dual plane intakes but honestly unless you are running a high performance engine it really wont matter all that much. You can grab a decent phenolic spacer off ebay for about $20.
I agree "go with a phenolic spacer"! I had a metal spacer on my car for a few years and started to idle ruff; discovered the spacer was not sealing properly even after gasket replacement. Went to plastic 1/2" spacer -- problem solved. I agree w/ William623 on the 1/2" versus 1 inch.
On a low rpm engine an open spacer can help if you have fuel distribution problems, you'll see one or two plugs burning differently. Had a Performer intake on mine once upon a time, two plugs ran rich and two ran lean. Put on an open spacer (actually a 1/2" nitrous plate) and everything smoothed out. Tall open spacers are generally for higher rpm use (they straighten out the air flow in a single plane intake) and four holes are used for lower rpms to keep the mixture velocity up for strong carb signal.
Either type spacer will run good. The 4-hole may improve low RPM throttle response and improve idle slightly. I agree on a phenolic or composite spacer. The ethanol in today's gas boils at a lower temp than the gas of yesteryear.
A buddy of mine that road races, says no spacer on that intake. So on my new build I didn’t use one. He dynos these 302’s so I suppose he knows.
