Phenolic Spacers

Heavy 488 wrote: the factory heat isolator/ gasket is closer to 3/8". Just like the one sold by Edelbrock#9266. They don't need to be over an inch to be effective. It has the grommets on all 4 corners so it can't be over torqued.

IB Sorgn wrote: ccowx wrote: Thanks, that is useful information. I do have minor heat soak issues, where the car doesn't want to start for about 5 or 6 seconds of cranking if it shuts down hot and sits for 10 minutes or so. I have long suspected that heat soak and the infamous Holley issues with that are happening. I don't have any spacer at all between my Holley and an R4B intake, due to a Ram air hood. I unfortunately don't have much room for a full spacer, but I wonder how thick the spacer would actually need to be? Perhaps a 1/8" insulating layer of something would do it? Chris  The smallest I've seen of a phenolic spacer was 1/2" and I believe Edelbrock has a Carburetor Heat Insulator Gasket which is about 1/3" but I don't know anything concerning their performance.

1/2" was the stock spacer under my carb on my 70. I think I still have a NOS one I could check again, but I went through the whole R4B under factory ram air fiasco on my 70. R4B sits 1" higher, take out the 1/2" spacer and it's still 1/2" higher than the factory intake. I did all the measuring years ago and posted the info here in the forum. I ended up cutting down the foam seal between hood and air filter tub to make things work, but couldn't run the spacer without troubles. You could hear the fuel literally boiling in that stupid Edelbrock carb. 

ccowx wrote: I have my stock phenolic spacer still, complete with PCV hook ups etc. I found that under a 70 ram air set up you could run the Holley and R4B but you could not run the spacer and you need a cut down foam seal. Back in the day I ran a Carter (Edelbrock) 625 competition series and it fit better than the Holley, but I don't recall if I used the spacer or not.  How thick does an insulating spacer need to be? Is the heat soaking into the bowls just by rising off the intake or is it actually being conducted through the metal? Thanks! Chris

GM had some heat shields if I recall that might help with the float bowls. My issues are relatively minor, it will always start but it's a bit embarrassing to have to crank it for that long. Perhaps a few layers of cork gaskets? I should have room for that.

I also block the heat crossover. Trust me, where I live there is not much likelihood of my going for a drive in December.