Carburetor Heat Shield

[tlslack]

My 1965 Tiger has a 289 HiPo with a heat shield between the 670 Holley street avenger carb and the aluminum street domminator intake. I assume that a previous owner installed the shield due to the car being used for auto cross. I would like to remove the shield because it interferes with the new chrome fuel line I want to install. The car is no longer raced, just use it for pleasure in Wisconsin climate. The car has a LAT hood with intake and exhaust vents. Will I notice any heat related carb issues if I remove the heat shield?

 

[michael-king]

My 1965 Tiger has a 289 HiPo with a heat shield between the 670 Holley street avenger carb and the aluminum street domminator intake. I assume that a previous owner installed the shield due to the car being used for auto cross. I would like to remove the shield because it interferes with the new chrome fuel line I want to install. The car is no longer raced, just use it for pleasure in Wisconsin climate. The car has a LAT hood with intake and exhaust vents. Will I notice any heat related carb issues if I remove the heat shield?

The heat sheilds generally act to stop the hot air heating the underside of carbs, in a tiger i'm sure it helps a little, but likely the carb ends up being heated anyway... what i would recomend is that when you remove it buy a Phenolic spacer for between the carb and manifold otherwise you might notice the car develops a stumble on takeoff in hot weather and more difficult restarting.

 

[TigerBlue]

heat related carb issues

Yes! U may notice heat related carb issues if you remove the heat shield.

The carburetor float bowl(s) can boil or percolate when heat builds up in slow moving traffic. An insulator between the carb and the manifold is helpful. Boiling is easy to clear if you can turn off the fuel pump with the key still on. Otherwise it is hard (impossible?) to stop the flooding unless you turn off the key and park it awhile.

Rick

 

[tlslack]

Carb heat shield

Thanks for the replys. I do have a toggle switch on the dash for the fuel pump, so I could turn it off shortly before turning engine off. I will have to measure, but I may only have enough hood clearance for a 1/4 to 1/2 inch phenolic spacer. I may be able to trim my thin aluminum heat shield to clear the fuel line. If so, would a small heat shield give better heat/carb protection than a 1/4 inch phenolic spacer?

 

[michael-king]

Thanks for the replys. I do have a toggle switch on the dash for the fuel pump, so I could turn it off shortly before turning engine off. I will have to measure, but I may only have enough hood clearance for a 1/4 to 1/2 inch phenolic spacer. I may be able to trim my thin aluminum heat shield to clear the fuel line. If so, would a small heat shield give better heat/carb protection than a 1/4 inch phenolic spacer?

Depending on manifold you are unlikely to fit more than a 1/4 spacer.. if i had to choose i'd go the spacer over the heat sheild... what air cleaner are you running.. the stock one might cause issues.. but a triangular filter or round one might give you clearence if you have a LAT hood as it might sit up into the scoop.

 

[Duke Mk1a]

I had my manifold's carb surface machined down to make room for a heat shield/spacer. Works like a charm.

 

[VaCat33]

1/4 inch spacer

Hi All,

Hope evrybody had a nice holiday.

Based upon my unscientific measurements using modeling clay, I figure I have just under a 1/2 inch between the top of the air cleaner screw and the hood (I am running an f4b, Holly 465 cfm, and stock oval air cleaner).

In the absence of major work (at least for me) suggested by Duke, does anybody have a make/source for a 1/4" phenolic spacer. I check several places but everybody just seems to have the 1/2" and 1" types.

Thanks,
Jim

 

[66TigerMK1A]

There's this one from Jegs...

http://www.jegs.com/i/Jomar/519/5025/10002/-1?parentProductId=

 

[VaCat33]

Thanks...This looks as if it is just what the doctor ordered.

I think I visited this site when I was surfing, I just did not see the 1/4 inch spacer available first time around.

Jim

 

[michael-king]

Thanks...This looks as if it is just what the doctor ordered.

I think I visited this site when I was surfing, I just did not see the 1/4 inch spacer available first time around.

Jim

I saw summit had 2 brands of 1/4" not long ago.. but one was plastic one was fibre

 

[Duke Mk1a]

Based upon my unscientific measurements using modeling clay, I figure I have just under a 1/2 inch between the top of the air cleaner screw and the hood (I am running an f4b, Holly 465 cfm, and stock oval air cleaner).

Here is another way to measure. Take tinfoil and roll some into a loose ball ~ 1" in diameter. Make several and then tape them to the top of the air cleaner where you think the tight spot is. Close the hood, then open hood and the tinfoil balls will now be pressed into the exact clearance you have. Just measure the now squished ball and that is your clearance.

Here is the heat shield/spacer I am using - http://www.summitracing.com/parts/HLY-108-70/?rtype=10 the spacer is .25"

 

[tlslack]

Carburator Heat Shield

Thanks for the feedback. My old heat shield is small and has cut outs that accually expose about half of each bowl to heat from the intake. Sounds like the 1/4 inch phenolic spacer would be more effective, and it should fit. I have the oval AC air cleaner which has lots of clearance above the wing nut due to LAT hood, but much less at the front outside edges. Easy to see thru the air intake and use a stiff 1/2 wide tape measure to guage the clearances. Clearance at each edge is about 3/4 inch on passenger side and 1/2 inch on driver side. The engine is lower on the passenger side, and the LAT mounts appear to be in good condition and solid. Is this geometry by design to deal with engine movement during acceleration?

PS: I just talked to Holley Tech about the Holley Heat shield. They explained that the shield is about 1/16 inch thick but the top gasket is about 1/4 inch thick fiber for insulation. They thought it would work out better for radiant and conducted heat than just the phenolic spacer. Any other thoughts on that?

 

[TigerBlue]

Yes

I concur that both an insulator to reduce conducted heat and a shield to reduce radiated heat is best.

In heat transfer, conduction (or heat conduction) is a mode of transfer of energy within and between bodies of matter, due to a temperature gradient.

Thermal radiation is electromagnetic radiation generated by the thermal motion of charged particles in matter. All matter with a temperature greater than absolute zero emits thermal radiation.

Professor Rick