heat shield for my slant six!! HELP

[DaisyDart]

Hey everyone,
My 225 slant six is becoming a pain in my A**.... I have the classic heat soak no hot start issue its driving me nuts. I am doing the fuel mod, return vap line, im just missing the heat shield. But that's where my problem is. I cannot find a 1920 holley carb heat shield.
I know people have made one out of aluminium, I'm not that good with fabricating anything of the sort so im really wanting to find one i can buy.
I found this one... http://ezcool.ca/home/shop/ford-1-barrel-shield/
but I don't know if it would fit on the holley,
Does anyone happen to know if it would fit the 1920 or if they know where i can find one that WILL actually fit!
Thanks!!

 

[zkx14]

What was originally under the 1920? My 1945 has a thick (1/4" maybe) piece under it. New one came with the rebuild kit. Can't say if it would work or not.

 

[DaisyDart]

Mine has a 5/16 gasket ... I wanted to add the heat shield with the gasket

 

[66Dvert]

Hey everyone,
My 225 slant six is becoming a pain in my A**.... I have the classic heat soak no hot start issue its driving me nuts. I am doing the fuel mod, return vap line, im just missing the heat shield. But that's where my problem is. I cannot find a 1920 holley carb heat shield.
I know people have made one out of aluminium, I'm not that good with fabricating anything of the sort so im really wanting to find one i can buy.
I found this one... http://ezcool.ca/home/shop/ford-1-barrel-shield/
but I don't know if it would fit on the holley,
Does anyone happen to know if it would fit the 1920 or if they know where i can find one that WILL actually fit!
Thanks!!

I have not seen any pre-made ones.
I would buy a normal carb gasket,flat piece of aluminum .090 or a bit thicker like .125 (1/8") for extra heat removal or you could get an epoxy( phenolic) resin board that stops the transfer of most of the heat to the carb, my bet would be on the aluminum as a heat sink but it's your car. Then take a piece of cardboard(any type but thinner like shirt cardboard or poster board is better, usually 4 or more pieces since you ARE gonna oops a couple times and you need to shield all the way around of the carb)
remove air cleaner in /6 cut the posterboard so that it touches the gasket area (i cheated by pre-cutting it using the new gasket)of the carb and does not hit any parts such as hoses,linkage or choke system rods cut lightly in areas if you need to make a bend to clear anything. next take 2nd piece of cardboard and lay the first cut piece on it,place new carb gasket onto full uncut sheet next to the cut piece if cardboard mark for bends with dotted line if you need to. done with that? tape it all together and find a machinist who can make your pattern. it'll be a bit more expensive than buying a ready made one, but I have not been able to find one anywhere.

You don't need to fab it just imagine it and test with cardboard,tape and a little bit of thinking.

(BTW it does not have to be HUGE but I'd go with at least 3 inches past the outline of the carb for airflow and heat dissipation and clearance for the throttle linkage,choke ect.)

 

[pishta]

Considering the carb sits on TOP of the exhaust manifold (with an iron intake between them) it would be a great start to look for the cause of the heat. My guess is a stuck heat riser that is directing heat up to the intake stove. 3 options:
one is to fix (or investigate) the heat riser issue, make sure its free in its bore and the spring is functional. Imagine the slot in the heat riser as the position of the valve in the riser: The slot in the heat riser shaft points to about 11:00 when open (hot and redirecting exhaust down the exhaust) and will be about 2:00 when cold (directing heat up to the intake stove) I fits stuck in the COLD position after you warm up, its not working. a heated spring will pull it open
2. Install a blocking plate between the intake and exhaust. replace the metal gasket with a thin piece of sheet metal. Dont go crazy on the thickness as it will alter the intake/exhaust port relation.
3. Phenolic spacer under the carb itself. 1/4 minimum plastic, bakelite, wood, anything but metal including aluminum, they make cookware out of aluminum. Transfers heat well.
You already routed the fuel line away from the hot surfaces.

 

[slantsixdan]

That Ford heat shield will work under a 1920, you just have to drill the 1/4" diameter hole on the carb mount flange (use a correct 1920 carb flange gasket as a template).

Almost everything suggested in this thread so far is a good idea, except disabling/blocking off the manifold heat control valve.

 

[57dodged100]

I talked to one of the reps from the cool carb company at a national show. He told me he didn't recommend for the /6 because the core material had melted on some /6 users. Their website includes the following.

"This product is not recommended for the use on: 1. Intakes with heat crossovers and EGR values in the intake. 2. Straight 4-6-8 cylinder motors where the exhaust and intake overlap. 3. Some castiron intakes have had an issue also. REASON: The polycore is an excellent insulation but it cannot take the extreme heat that the exhaust creates. This causes it to get soft or melt."

 

[2 Darts]

"This product is not recommended for the use on: 1. Intakes with heat crossovers and EGR values in the intake. 2. Straight 4-6-8 cylinder motors where the exhaust and intake overlap. 3. Some castiron intakes have had an issue also. REASON: The polycore is an excellent insulation but it cannot take the extreme heat that the exhaust creates. This causes it to get soft or melt."

This is interesting in that they appear to be saying that this product is useless on most of the vehicles sold in the United States since 1971.

1. EGR systems came into common use in the US in 1972. All of them have vents under the carburetor which allow exhaust gasses to pass into the intake for re-consumption. Almost by definition, an EGR valve is in the intake on a carbureted engine. Technically, a heat crossover is only found on a V-type engine allowing exhaust gas to warm the carburetor.
2. I have not seen an inline, ohv, pushrod motor that didn't have at least two ports siamesed. If they are talking about valve overlap, then one has to go back to the powered buckboard days to find a gasoline engine without valve overlap.
3. This seems to be the only leg they have to stand on. Most carbureted cars built in the US since WWII have had cast iron intake manifolds.

Ask Dan to check me out on this. The throttle bore on the 1920 is 1 11/16, where the hole in the plate is 3/4. This means that the hole in the plate is 1/16 too large. IMO, that's not a big deal, but it can be if the bottom of the carburetor isn't fairly flat.

 

[slantsixdan]

1. EGR systems came into common use in the US in 1972.

Well, '72 in California, yeah. '73 in 49 states + Canada.

All of them have vents under the carburetor which allow exhaust gasses to pass into the intake for re-consumption. Almost by definition, an EGR valve is in the intake on a carbureted engine.

Some Fords and Volvos had a different arrangement, but we don't talk much about off-brand cars here. All Mopars with EGR, yes, have the valve on the intake manifold and require the exhaust/intake "overlap" (as they weirdly call it).

I have not seen an inline, ohv, pushrod motor that didn't have at least two ports siamesed.

The way I read their misuse of the word "overlap", they mean the intake manifold hot spot, heated by the exhaust, where the intake and exhaust manifolds bolt together.

This seems to be the only leg they have to stand on. Most carbureted cars built in the US since WWII have had cast iron intake manifolds.

Sure, but if that's a leg, it's a gimpy one. "Some castiron intakes have had a heat issue also" makes less than zero sense.

The throttle bore on the 1920 is 1 11/16

Or 1-9/16", depending on which specific 1920 (or Carter BBS, or Holley 1945) we're talking about.

where the hole in the plate is 3/4. This means that the hole in the plate is 1/16 too large.

Not an issue; the hole in the carb flange gasket is also larger than 1-11/16" and makes no problems.