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Phenolic Spacers
Is there a preferred thickness on phenolic spacers to control transfer of heat to the carb base? I've seen everything from 1/8" to 1/2"
? ? ? Paul |
Mine are 3/8" but they're not installed yet
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Mine are 1/2 inch and have not helped.
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I tried several thicknesses of phenolic spacers and didn't experience much improvement. I switched to a wood laminate (3/4") that was provided by a friend and the improvement was dramatic. Hard starting issues have been eliminated.
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I was limited on the height, so I went with a thinner phenolic spacer and added a Holley aluminum heat shield that goes under the spacer. I think that helped more. The bowls stay much cooler.
http://i389.photobucket.com/albums/o...ps16c21219.jpg http://i389.photobucket.com/albums/o...psbcd8263a.jpg Scott |
mine is 1/2" and it made a great improvement. I used them in my other cars and the heat transfer is greatly dissipated, just plain physics 101.
Lou |
I do not use spacers or anything other than gaskets, I do not have any heat related issues with the carbs. What is the problem that you are having?
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Gathering parts
I have begun a project to put Webers on my build and am gathering the parts for the project.
Research shows that most guys are running spacers, but few posted how thick they were. I currently have 3x2's installed on the FE motor and heat is a little bit of an issue when the motor/ambient temp is high - vapor lock. A friend has weber's on his 289 and they would drip if the heat was high. All reasons to reduce the bowl temp as much as possible. I will be ordering the phenolic and didn't know what thickness worked the best. Paul |
The thicker, the beter........
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If you have an actual cold air intake that helps to reduce the temps also.
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Make sure you check clearance with the hood.
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SPACERS
Hood clearance will determine how thick of a spacer you can use. The birchwood spacers offer the best thermal barrier I think. I have the 1/2" on my SPF/427R and it works as advertised. oops. sorry. Just saw your application is Webers. Disregard. Carry on. |
So where are you buying these spacers in multiple thicknesses or are you making them yourself? McMaster Carr has a phenolic coated baltic birch ply in sheet form that could be pattern routed.Regards, Jon
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Any form of insulating spacer makes some difference, but the carbs will still get heated from the engine and exhaust.
The inlet manifold heat still conducts to the carb base via the studs/nuts. I have found mounting the carbs in a heat shielded box and letting the outside filtered air to run around the bottom of the carbs prior to the top keeps them cool. Fully isolated insulators with studs top and bottom isolate the carbs better, but near impossible to fit on a V8. |
Google Weber phenolic spacer. Lots of places sell them
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As previously stated the carbs will still get heat transfer to them via the attaching method as well as convection from engine heat. As has been stated the carbs will boil over when heated, lets look at this problem. The carb designer built in enough area in the float bowl cavity to allow for the fuel to expand when heated, if the proper float bowl level has been set this problem should not occur. Like I have previously stated I do not run phenolic spacer, I would adjust the float level accordingly. You may have to reduce the float level to get satisfactory results. Here's a little trick to reduce the float level height but increase the float bowl volume:
1) remove the top of the carb 2) remove the gasket between the carb top and bottom 3) look for the little cavity next to the float bowl that has nothing but air in it, opposite side from the accelerator pump piston chamber 4) remove the material between the air cavity and the float bowl, you have just increased your float bowl volume 5) now set your float level lower |
Quote:
Lou |
I had my webers and custom turkey pan built by Jim Inglese for my Daytona. I think the kit came with 3/8" phenolic spacers. Also had to have the stacks custom cut to fit under the hood. (shell valley replica)
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there is that gold colored heat shield that might provide some benefit if applied in the right areas.
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