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Phenolic Spacers

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billd View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2021 at 1:28pm
Originally posted by ccowx ccowx wrote:

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

Thanks!

Chris 


LOL - been up that way - it was abnormally warm and dry that year but I suspect there's not a lot of chance going for a drive in October, either. Since these aren't all daily driver cars any more, few get driven in temps under 40 or 30, if you can deal with them being a bit "cold blooded" and have an electric choke or manual choke, you can block that without a lot of issue. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2021 at 1:46pm
Funnily enough, last winter my baby spent it's first night outdoors in 30 years due to some needed repairs on the daily driver. It started perfectly at -35, though it DID NOT like it much! Actually started easier than cars young enough to be it's children, despite summer weight oil, light choke setting, etc. 

I won't be doing that again!

Chris 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2021 at 3:35pm
Heck, these days it's hard to get me started when it's below 20 degrees out........
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sweatlock Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2021 at 3:38pm
Canton sells 1/4” thick phenolic spacers for the vertically challenged. There are several for sale on eBay, just search for “1/4” phenolic spacer” 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/20/2021 at 4:39pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IB Sorgn Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2021 at 2:38pm
Originally posted by ccowx 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 
 

According to my laser the heat transfers to the spacer but at a much lesser degree, then, obviously to the carburetor. My gun showed about  23 degrees less.  I would assume if you had a larger spacer the heat transfer would be even less.  It's like the more insulation the better but I'm sure there is a point of diminishing returns.  Should also state that the bolts and nuts contribute to the transfer as they were about the same temperature as the manifold. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote FSJunkie Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2021 at 3:40pm
Generally increasing the spacer thickness beyond 1/2 inch doesn't help much. There is a certain point where the heat soaking into the carburetor body is coming more from radiation and convection around it rather than contact transfer. 

In other words the air around it is hot.

This is coming from somebody who sometimes (when I cannot avoid it) must drive their carbureted cars in 110 degree weather. 

Even with a spacer, heat shield, or whatever, it's still normal for a carbureted engine to percolate fuel in the carburetor after hot shutdown, and require the throttle to be held partially open while operating the starter to restart. Most any engine even in extremely hot conditions should start within a couple seconds if you hold the throttle partially open while operating the starter. In fact, many owner's manuals published at the time told new car owners to do exactly that. It was considered a normal condition, and drivers we taught how to handle it. 


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Post Options Post Options   Thanks (0) Thanks(0)   Quote ccowx Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2021 at 3:55pm
Yes, it was normal for drivers to understand how to set an electric choke, deal with a flooded engine, etc. I remember being taught to start my mother's car so it could warm up (another lost art!). I had to turn on the ignition, push the pedal to the floor and then turn the key, which would completely baffle my kids!

I had wondered about the bolts themselves and there is the ambient temp as well underhood. I park it with the hood up in my garage but obviously I can't do that at the mall. 

I might try removing my ram air ducting and put in the original spacer again. If that helps a lot I might decide to try to figure out how to get a thin insulator under the carb. 

Thanks!

Chris 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Trader Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2021 at 4:43pm
We used to make spacers out of plywood years ago. R value on 1/4" plywood is 0.3. Phenolic has an R value of 4 to 5 per inch, so they are very close. Made one out of engineered flooring last year (very flat and easy to work with), just cost my time which was not long for this. Gaskets make great templates.
Used fiber washers under the carburetor mounting nuts and you will find very little heat coming from the intake.
Don't know the R value of the engineered flooring but the the person seems happier now with starting and no vapor lock after rerouting the fuel line also.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote billd Quote  Post ReplyReply Direct Link To This Post Posted: Jun/21/2021 at 4:53pm
Originally posted by ccowx ccowx wrote:

Yes, it was normal for drivers to understand how to set an electric choke, deal with a flooded engine, etc. I remember being taught to start my mother's car so it could warm up (another lost art!). I had to turn on the ignition, push the pedal to the floor and then turn the key, which would completely baffle my kids!

I had wondered about the bolts themselves and there is the ambient temp as well underhood. I park it with the hood up in my garage but obviously I can't do that at the mall. 

I might try removing my ram air ducting and put in the original spacer again. If that helps a lot I might decide to try to figure out how to get a thin insulator under the carb. 

Thanks!

Chris 


Steel isn't a great conductor - very very little goes through those little 1/4" studs. Get that flat aluminum carburetor throttle body against a flat mating surface and it's a different story. The mounting legs are generally out a ways from the body as well. Some, yeah, but nothing to write home about. By the time you get up 1/2" or so, with gaskets in there as well, should be pretty good. You seldom see a stock spacer over 1/2". That seems to be their break point. 
I've wondered about a thin aluminum or brass plate - well, put a gasket, aluminum or brass plate with holes to match the intake holes but the plate sticking out from the intake and carb all the way around like a cooling fin, then a gasket, then a spacer, then gasket, then carb or even the spacer, gasket, then plate to act as a heat sink/cooling fin.
That plate would also absorb heat radiated up from the hot intake - a whole lot like the metal shield attached to the hydraulic clutch line on my Eagle. It's a simple piece spot welded to the hydraulic line that goes to the slave cylinder since that line runs only a couple of inches away from the exhaust head pipe. Doesn't take much. 
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