Fuel System: Heat soak

[Flat Ernie]

Car: '53 C w/289 & Edelbrock on cast iron intake

Starting to address my fuel issues - they are minor, but annoying.

One of the issues is when the engine is hot and I park somewhere, when I come out after 15-20 mins or more, the fuel seems to have evaporated out of the float bowl and I have to crank the engine over several seconds before the bowl gets refilled.

I'm generally a Holley guy, as I don't care for the Edelbrock/Weber/Carter style carbs as I find them finicky to tune well - don't want to get into a debate on this, just a data point.

One of the things I've noticed on the two cars (one prior non-Stude) with Edelbrock carbs is this heat soak issue. It wasn't as bad on the other car, but it had an aluminum intake. I'm assuming the cast iron is holding the heat a lot longer and 'boiling' the fuel out of the bowl.

While I realize I could pull the intake and block off the heat riser, I figured my first step in addressing this would be to put an insulating spacer under the carb. There's currently a 1" thick aluminum one. I had a 1" plastic one and popped the carb off to try it this weekend. To my frustration, the Stude intake uses the small bolt pattern on the 4-bbl intake and this particular spacer only had the wide pattern.

A couple new gaskets and everything was back. Figured I'd search for a spacer with both sets of holes, like most of the gaskets have. Well, only found one brand, transdapt, that has insulating spacers with both bolt patterns. The problem is, they want $135 for it!!

So, short of fabricating one on my own, does anyone know of another insulating spacer (I don't care about material - plastic, phenolic, teflon, what-have-you) that has bolt bolt patterns. Oh, and I will only use a ported, 4-hole spacer (I know..getting picky now).

Any suggestions before I start collecting bottles to save up for a spacer from transdapt?



I had wanted to avoid pulling the intake and blocking off the heat riser, but that may be the ultimate solution and since I live in the south, won't be much of a driveabiiity issue.

[dynolou2]

The ultimate solution is not hard, compaired to a chev or ford no water or antifreeze to deal with no disturbing the dist. Did you remove the heat riser? I have found that the carb can get hot enough for me to not want to hold a hand on it.
remove heat riser, put intake gaskets with block off plates on, if you really want to get fancy, crumple up heavy duty aluminum foil fill up the crossover. Putting on spacers of whatever type won't do much when you have full exhaust heat flowing under the carb. Lou Cote

[JoeHall]

How bout this one: http://www.ebay.com/itm/Clifford-int...ZW7a7v&vxp=mtr

[JoeHall]

Or this one: http://www.ebay.com/itm/Carb-Carbure...dW4XLJ&vxp=mtr

[JoeHall]

Another thing you can do is run a manual choke. With heat soak, the problem is often compounded since the choke coil quickly cools enough to close the choke, yet the manifold remains hot enough to boil the gas out of the bowl and resettle it in the intake. Then, you are trying to start a flooded motor with the choke closed. That is one reason why it must crank so much. With a manual choke, you have control, and just keep the choke open at that time.

[JoeHall]

If you block off the heat riser, it will warm up much slower than the electric choke. So you'll need to set the electric choke real rich in order for it to stay on longer. The other solution is to run a manual choke.

Worst of all, closing off the heat riser only delays the inevitable; 20 miles down the road, the carb will be the same temp as the rest of the motor. So heat soak will again occur. At least that was my experience.

[Flat Ernie]

How bout this one: http://www.ebay.com/itm/Clifford-int...ZW7a7v&vxp=mtr

Or this one: http://www.ebay.com/itm/Carb-Carbure...dW4XLJ&vxp=mtr

Those are both aluminum and won't work for what I'm looking for.

Another thing you can do is run a manual choke. With heat soak, the problem is often compounded since the choke coil quickly cools enough to close the choke, yet the manifold remains hot enough to boil the gas out of the bowl and resettle it in the intake. Then, you are trying to start a flooded motor with the choke closed. That is one reason why it must crank so much. With a manual choke, you have control, and just keep the choke open at that time.

I've got a manual choke.

If you block off the heat riser, it will warm up much slower than the electric choke. So you'll need to set the electric choke real rich in order for it to stay on longer. The other solution is to run a manual choke.

Worst of all, closing off the heat riser only delays the inevitable; 20 miles down the road, the carb will be the same temp as the rest of the motor. So heat soak will again occur. At least that was my experience.

True enough, but most of my running around town won't ever see these heat saturated temps at the manifold. Further, the air-gap style of the intake allows it to cool a little quicker than the rest of the engine and remain a little cooler overall, but I hear what you're saying.


Where I was originally going in my first post commenting on being a Holley guy is that Holley doesn't seem to have this problem (or not nearly as bad) due to the design of the carb; the float bowls are surrounded by air on all but one side that bolts to the metering block, so there seems to be less heat transfer to the bowls in a Holly...and I'm tempted to just bolt a Holley on and be done with it!

[jclary]

I wonder how much heat you are retaining, and for how long? Is it severe, or are you on the edge of the spectrum where a tiny bit of additional cooling will be sufficient?

One thing to check could be to change from the big factory air filter, to a smaller aftermarket filter for around town driving. I have no science to back up my theory, but those big air filter bonnets seem, to me, like additional metal bulk that gains heat and holds it hovering and reflecting it back to the carburetor. You could try that and see if it makes a difference. Just make sure you get one with sufficient air flow.

Of course, if you are not using a factory filter already, that pretty much blows my theory.

[PackardV8]

To my frustration, the Stude intake uses the small bolt pattern on the 4-bbl intake and this particular spacer only had the wide pattern.

Any particular reason you don't just use the small hole gasket to mark the pattern and drill the needed holes? It's just plastic.

jack vines

[Tom Bredehoft]

Solution to vapor lock/heat soak, Install a fuel return line from the carb to the fuel tank, (put a .040 restriction between the carb and the tank). This way the fuel will be cool when it gets to the carb upon start up, and will fill the float bowl quickly (it vaporizes in the pump, too)

[Mike Van Veghten]

Easy fix.
If the problem is fuel evaporation from the bowl...
The car sitting more than 3 or 4 days ends up the same...dry float bowl.

Install an electric fuel pump.

Instant fix.

Mike

[JoeHall]

Looking around on the internet, I see what you mean about nonavailability of, other than aluminum, adapters for your application. I realize this won't help you, but I have one of these on the 56J, with a Holley model 4360 carb, and manual choke. I agree Holleys are less prone to heat soak/vapor lock, at least the 4360 is. To bad they don't make one of these adapters for your application: http://www.ebay.com/itm/Spectre-Perf...VWFUnp&vxp=mtr

[JoeHall]

There have been three, 1-step "cures" listed above: heat riser; return line, and electric pump.

I have found, if one takes several steps (excluding the heat riser), then heat soak/vapor lock is reduced to tolerable, but just tolerable. The "package kit" includes: electric pump (toss the mechanical); return line; carb spacer (not sure phenolic is any better than aluminum); aluminum heat shield beneath the carb (similar to earlier fuel pump heat shield), and HD cooling system.

[Kenmike2]

Take a look at WWW.STUDEBAKERSONLY.COM I;ve been making and selling these spacers for about 10 years. Sorry I didn;t see this sooner.

Ken Michael

[joncon]

I bought mine from Summit. That's it on top of the carb adapter. I also have the return line on the filter and a electric fuel pump. It's still hard to start when the engine is warm and it's 90 or so in the summer.