[tekenaar]

How important is the heat shield under the carburetor? Seems to be a big PITA! If it's not that necessary, I would like to remove it.
Bob

Keeps exhaust manifold radiated heat away from carb, specifically carb bowl, to reduce fuel percolation and "hot start" problems due to this. Overall temperature reduction of carb body is NEVER a bad thing.

I always use one and even fabricated one for my single sidedraft installation (see pic). Especially important to use one with the stock "joined" manifolds setup, as you already have to deal with a lot of heat from the "stove" under the intake plenum. That's JUST my opinion, though.

 

[tekenaar]

More heat reduction ideas . . .

. . .

So it sounds to me that retaining the heat shield is a good idea for an aftermarket Weber, and critical for the original Solex.

While we're on the subject of "heat retention", if ANYONE is still using the original metal line across the front of the engine and a metal can fuel filter, I STRONGLY RECOMMEND that you replace the metal can filter with a clear plastic one and wrap the entire exposed length of metal fuel line with 1/4" plastic "split wire loom".

You'd be amazed at how quickly and thoroughly any underhood exposed metal absorbs and retains radiated heat. NOT GOOD! The plastic split wire loom and the small air pocket it has effectively shields your metal fuel line from this radiated heat. Replacing the metal can filter with a plastic one is pretty self-explanatory.

 

[tekenaar]

Re: weird and heat shield

A:
this is weird...the exhaust manifold is designed to heat the carburetor..with its heat riser....now we talk about heat cooling it with a heat shield....

. . .

Originally posted by bucky
B:
1-does a weber 32-36 (or other carburated format ) NORMALLY need a heatshield to prevent a "dry bowl when engine is hot"

2-does a sprint exhaust bypass the need for a heatshield?

3-my understanding here..is that most people are running without heatshields...especially if they have changed carbs...

4-should a mechanical fuel pump be wrapped in insulation to prevent its absorption of heat?

A:
Exhaust manifold is actually designed to heat plenum UNDER carburetor to help emulsify fuel/air mixture FROM carb, NOT really the carb itself, though that IS a byproduct of the design and, hence, the reason for the heat shield under the carb.

The better the mixture is emulsified, the better it burns. In cold weather, gas in the mixture in plenum is more likely to return to liquid state and, remember, liquid gas doesn't burn very readily.

B:
1. ALWAYS a good idea!

2. No, still a good idea!

3. What about good idea is not clear?

4. May be worthwhile, but "vapor lock" usually occurs in the gas line itself (smallest passage, easiest for "vapor lock" air bubble to form).