Oriondriver

I am thinking about putting a 1/2" spacer btwn the block and Speed Demon carb... anyone use one?

Thanks
Scott

Plasticman

What is the purpose of you adding the spacer?

Spacers are a good start for isolating the heat of the engine from the carb, and I do run a couple (due to boiling of the fuel in my AFB's, but I did several other mods to help correct that issue as well - block off the heat riser passagway in the heads, add a lifter galley plate to prevent hot oil splash onto the bottom of the intake, etc.).

They are also usefull to increase the effective area in the intake plenum, which helps high RPM performance a tad.

Plasticman

millmanjoe

2 things the phenolic spacer will help is:
1-Help to keep the carb insulated and away
from manifold heat.
2-Add more velocity to the fuel delivery.
BUT.....The spacer geometry needs to be designed to direct the fuel
in the best direction to get there fast. So just raising the carb may not
due much good as far as H.P. I also haven't heard much about a 1/2"
usually it's 1" or 2" for any results. If you have the clearance go for 1" if you can.

What are you actually trying to gain?
If you put it on and notice a differance, great!
If not boo!! You may need to re-tune your carb,or remove the spacer.
Only true test of differance would be Dyno.

Oriondriver

Thanks for the input... I am trying to insulate the carb from the block... pretty confident the carb is getting hot... I am looking at the 1/2 inch simply due to clearance...

Scott

Geek's 65

Scott,
The spacer will help but as Plasticman pointed out, blocking off that heat riser on the intake is a big plus. You can plug the two holes below the carb that feed the heat or, if you want some heat there, FelPro makes intake manifold gaskets that put a stainless plug over the riser in the head that has a half inch hole in it to let some heat pass. That's what I did for my AFB. Makes it a touch more cold blooded (relative for California) when you first start out but much cooler overall. FelPro part number is a 1256 for the SB.

thomaswat

What do you plug the two holes below the carb with, and exactly where are they ??

62Jeff

Check out post #20, from Magic, in this thread
http://forums.corvetteforum.com/show...carb+heat+plug

Oriondriver

The symptoms I am trying to resolve include... engine won't shut down when I turn off the ignition and there is sometimes blowback out of the carb after I shut it down... indications of the carb being too hot?

Thanks
Scott

Paul L

Scott,
You probably have a timing issue.

Black60

Hi Scott:
A fast idle will do exactly that. Turn down the idle a bit and try it.

As Paul points out timing can cause lots of issues however if you are so far advanced that she is running on detonation after shutdown you are experiencing other things even more damaging during driving. She would be severely detonating (pinging) during hard acceleration. Because you have not mentioned that I assume it is not the case.

Lots of great tips but I'd put my money on fast idle.

Best Regards,
Ralph

GUSTO14

You could also try one of these...

They're available from most high performance engine shops, or you can do what I did... make your own.
Make a template out of cardboard that fits your specific application and then take a thin piece of aluminum and cut it out. Place it between two gaskets and it will do the job of most insulators plus... shielding the fuel bowls from radiant heat.

I like to make them myself because most purchased ones have to be trimmed to fit your specific situation and also end up giving up some coverage because they tend to be fairly generic. By making your own, you can better tailor it to your specific application.

Good luck... GUSTO

drd1vette

Gusto, that's some pretty nice work you made there!

Oriondriver

CONCUR... how about I send you a cardboard template...

Paul L

I have not blocked the intake crossover passages but I have had the heat riser welded open which basically has the same, if not as dramatic, effect. The insulator I use (it is not truly a spacer) is from Edelbrock and is 0.30" thick or nearly 3/8". I do not experience bowl boil-over.

The comment on idle speed is a good one although you may still wish to check the timing. A combination of a proper idle speed and timing will probably solve your problem. My 327 is a mild version with Powerglide. It idles about 650 in Park and 550 in Drive. Static timing is about 10* BTDC. I do not get pinging with 91 octane. And the engine temp is a pretty steady 180* with a 180* thermostat at speed. That can rise to 200* in stop-and-go city traffic on a very hot day.

You need to do, or have someone do, a little tuning for you.

GUSTO14

Actually that's not mine...:o it belongs to Jeg's... but the ones I've made looked about as good. It just depends on how much work you want to put into them. I usually polish them a little and then clear coat them to keep corrosion down. The last one I did was for a BOSS 302 and even though it was a Holley, it would not clear a Holley on a SBC.

But seriously the biggest advantage is that with all the stuff we have on our manifolds, making one for your application that clears everything and maximizes heat shielding, is one of the biggest bangs you can get for your buck.

GUSTO

Coves4me

Oriondriver, check out Jegs and look for a Mr. Gasket product that consists of a packet of gaskets and aluminum plates that sandwich together about 1/4-inch thick to keep heat away from your carburetor. I found it in the carb section of their catalog and use it under the AFB's on both of my cars. No problems on either since these insulators were installed. I believe it is part no. 720-97 at $14.98.