Heat Shield/Vapor lock

The word 'gas' can refer to a fluid that is not a liquid.

In this post we are talking about 'gas' meaning 'petroleum motor spirit, highly flammable', arent't we?

Yes, that's right. The situation is that design of the Model -T /Doodle Bug cowel is set up this way. When its coll outside there is no problem but on a hot summer day the fuel valve/bowl heats up and causes vapor lock. Once it's allowed to cool down a bit everthiong is ok. I'm trying to reduce/ eliminate the situation.

I once had a '53 Ford flathead V-8 that had the same problem (as did all other Ford products in that era). The classic fix was an electric fuel pump but that might require modifications that would be unacceptable for your antique.

I think my previous heat shield suggestion would work.

My brother-in-law had a '54 Mercury which did the same occassionly. He stopped for gas somewhere in Arizona, and the thing vapor-locked. Fortunately, there was a roadside fruit and vegetable stand next door, and they had just gotten a box of grapefruit and other citrus off of a refrigerated truck, so he bought one, cut it in half, and plopped one down on the fuel line, and the other went on the fuel pump. Cranked up and went on his way.

thank you for the info

Brian

thank you for the info

Brian

Many Chevy Corvette models are designed with the starter located very close to the exhaust manifold, resulting in starter armature aging that causes hard starting and heat soak.

To eliminate the problem and shield the starter and solenoid from radiant heat an aftermarket starter heat shield is available. It's a flexible blanket that is wrapped and secured around the starter. I would think the same material and shield would be equally effective to shield your gas valve.

This heat shield is available from Mid America Motorworks (www.mamotorworks.com), part number 106-905 at a price of $29.99.

Thank you for the info

Brian

Bluestone has a good idea.

Also, metal sheets/heat shields with a sizable air gap between fuel line and shield and exhaust and shield, attached to both the fuel line and around the heat source. (I actually mean two shields and not physically connected to each other either. In stainless steel if possible and polished!)

They are used extensively in the car industry, even today. They are also used often to stop the catalytic converter setting fire to grass under the car and the car itself.....

You must have a reasonable air flow in the area as well of course to get rid of the heat too.

They must be firmly attached, but could look quite correct too.

Your problem is radiated heat I feel, at least mostly and it needs to be fixed immediately...

Thanks for the info

Brian

I used a metal cookie sheet and some tin snips to make a simple shield and bolted it onto a frame member. Bolt it above and below so it does not 'flop' or vibrate or it will break off. Any form of non flammable material of any thickness will work. To test the concept, fire up a burner on an electric stove to create radiant heat and feel it with your hand sideways (not over the top) and then pass anything between your hand and the burner (even a piece of paper . . . being careful) and you will feel a remarkable heat difference.

Yep, let the air keep it cool it's radiation you're up against. If your setup uses a mechanical lifter pump (e g off a camshaft) it works by sucking and the fuel in the line will be below atmospheric pressure encouraging it to vapourise ( ok maybe only a little). I guess this is why people recommend an electric pump but to work properly mount it at the back, under the tank say (avoiding the exhaust). Recirculatory systems such as we have these days help. Some manufacturers have had to resort to heat exchangers to cool the fuel off the a/c for some markets, such are underbonnet temperatures nowadays. Henry didn't know he was born when he did the 'T'!

BTW I've heard other old car enthusiasts say unleaded fuel is more susceptible than good ol' leaded (it certainly deteriorates quicker and can have a bad effect on the internals of the fuel systems of old cars)

thanks for the info

Brian

thanks for the info

BRIAN

New cars use aluminium sheets around the exhaut mainfolds. I remember seeing my Dad putting clothes pins on the gasline for a 1946 Ford. I asked him why he did that. He told me that it drew the heat away and keep the gasline for vapor locking. Of course you could relocate the gasline.

You need 2 separate devices--1st is a radiant heat shield to block the high flux from the exhaust pipe. Shiny aluminum or stainless sheet,even foil backed with fire resistant material like NOMEX or high temp fiberglass cloth(aircraft firewall heat shield is perfect). This will reduce heat transfer maybe 80%. Then an insulating sleeve around the fuel line and valve will reduce conducted heat. Household foil backed glass fiber batting (3.5" is plenty) wrapped and secured with wire ties (do not compress the insulation more than necessary. )

I had a Citroen SM for over 20 years, and that Maseratti engine had massive exhaust pipes from each cylinder feeding large collectors. Citroen had formed stainless steel heat shields everywhere, including the individual exhaust pipes from each cylinder--two layers of stainless separated by 1/8" of woven asbestos, held off body or other parts 1/4" to reduce conduction even further. Worked like a charm. You could not feel any heat from the red-hot exhaust pipe on the other side of the heat shield.

Aaahhh! One of my favourite cars, was yours carb' or injection? Would have expected less trouble with the injection version. Down-draught fixed choke carbs suffer, in my experience, most from under-bonnet heat. At least from the point of view of hot starting. Different thing from fuel line vaproisation I know.

Thank you for the info

Brian