Gary's '66

I've read old posts and checked quite a few parts houses including Holley but can't find an insulator/spacer for the 3 hole manifold anywhere. Is it possible to use a 4 hole insulator?

Nowhere Man

Why would you need one and if found one wouldn't that cause hood clearance problems

Gary's '66

Just thought it'd look good
Joking aside, the reason is I think the carb is getting a bit too hot. Car starts, idles and runs strong until I'm in traffic and temp. is over 95. Then the idle will begin to fluctuate and stumble and the motor feels sluggish. I'm only thinking of something about a quarter to a half an inch thick but would use putty to be sure I have enough clearance

SS409

I had a 3/4" open spacer on my 66 L79 and had no hood clearance problems with the stock air cleaner when I got the car back in feb. I removed it shortly there after.

Gary's '66

That's something else I've been wondering about. Can an open spacer be used on the '66 L79 manifold? Good to know about the clearance. Why did you remove yours?

SS409

IMHO, an open spacer could disrupt fuel distribution. It was aluminum and I didn't see a need for it so out it went.

Gary's '66

That's what I was also thinking.

Matt Gruber

4 holer will work great. i make mine from .2" plywood to extend under the bowls to deflect heat.
open spacers for racing only! can cause stalls on cold starts, poor mpg, etc.
.
also consider a fuel pump isolator if the problem persists.
.
a 3-4" fan/duct works wonders. carb loves a cool breeze.
get dryer duct from home depot. 12v fan from old pc.

Nowhere Man

Did you think it could be something else like your timing or vacumn advance going bad

Gary's '66

Hi Matt
I was hoping you'd chime in. So, a 4 hole will work. That's what I was wondering.

Gary's '66

Vac advance seems ok. Is there another way to test it other than sucking on the hose? Other than the vac can how would timing be the problem?

Nowhere Man

Do a search on Corvette cooling systems written by our own JohnZ Or John Hinkly. And go from there it's a great article

Gary's '66

Thanks, but the car isn't over heating. I think I may have a percolating issue hence the the spacer/insulator.

Gary's '66

Matt
Just to be clear. I would use a 3 hole base gasket, 1/4 inch 4 hole spacer/shield, 4 hole gasket, then carb. Is that correct?
Gary

kingwoodvette

What about connecting (sawing out) two of the holes of one of the 4 hole isolators to make a 3 holer to match the L 79 manifold?

Hitch

Volley makes one that also includes an aluminium shield too...

Gary's '66

Kingwoodvette,
I thought about doing that but Matt says 4 holes is ok which kinda makes sense. If I use the proper 3 hole base gasket then a 4 hole plate. Since the carb base is a match to the 4 hole plate there's still a division between the planes.
Hitch
I googled Volley and all I got was volley *****, lol. Can you be more specific?

Hitch

Holley

kingwoodvette

Gary/Hitch, I have picked up one of thr Holley fiber 4 hole combo isolator heat shields. That was the one I was thinking about modifying into a 3hole. May just try as is with the 3 hole gasket between the isolator and manifold.

Gary's '66

Thanks Hitch, it should have registered.
Kingwoodvette
It does make sense when you think about it. The carb base is 4 hole and same configuration as the heat shield, the carb is just a 1/4 inch higher.