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Discussion Starter · #1 ·
'57 210 with 265

I'm having a problem with vapor lock and am trying to attack it from as many angles I can. I've wrapped all of the fuel lines and have closed off the cross-over ports to the carb. These have helped, but I still have the problem after about an hours' drive and then stopping at a stop light.
As I start out from the light the engine starts to stall but if I pump it hard and down shift and pop the clutch it keeps going and after a few seconds is going fine -- until the next long stop light.

I've measured the temp at various points and have noticed that the mechanical fuel pump is very close to the exhaust manifold and that the manifold is seriously hot. Is it possible that the fuel pump is getting too hot?

Assuming that it is (I will take some hard temp measurements and post them later) getting too hot, I think that there are a few things that I could do.

I could run a return fuel line and install a bypass fuel filter to keep the fuel flowing and thus not let it heat up in the line as much. This would be tricky as the current line was difficult to route and I'd have to pull the gas tank and tap into the neck. This also seems to sidestep solving the actual problem too (again, assuming that heat is the problem).

I could attempt to reduce the heat that the fuel pump is exposed to from the manifold by either wrapping the manifold or having it ceramically coated. I've read all sorts of postings that lead me to question whether the radiant heat generated from the manifold would actually be reduced significantly by either. Do any of you have any experience? Do either of these significantly reduce the heat from the manifold?

I don't think that I can put a thermal break between the fuel pump and the block because of tolerances (a double thick gasket and the pump may simply not work). I also can't think of a way to put a thermal shield around the pump itself.

Right now I can't drive the car very long before the vapor lock starts, and it's still early summer. In another month or so it will really get hot and then the car will have to sit until it cools off in the fall/winter -- unless I fix the problem now.

What do you think?

Should I have the manifold ceramically coated?

Is there some way to cool off the fuel pump ( aside from switching to an electric pump)?

Should I bite the bullet and run a return fuel line and install a bypass fuel filter?

Any other ideas?

-- Dennis
 

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Trifive Automotive Electrical Wiring Expert
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Have you tried a fiber spacer between the manifold and carb?
Do you have stock rams horn exhaust manifolds? Is the heat riser valve opening?

P.S. There is a vent hose in a 57 gas tank that a return line can T into.
 

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Have you checked that the carb mixture screws are not set too lean,also timing correct and not too advanced? This will contribute to the problem. Also check that all line fittings are tight and all rubber fuel lines are not weather cracked as the fuel pump may suck air bubbles into the fuel line. As previously noted,a bakelite or phenolic insulator mounted under the carb may help.Also another thing to look into would be a low pressure electric fuel pump close to the tank ans a pusher or puller elect. fan. Hope this helps. Bob :anim_25: :bowtieb:
 

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I have been having similar problems with the heat. No issues with the car running, but it just seems like the temperature under the hood is excessive. I can run the car, all day and stay cool, but when I stop at a long light and have to sit through multiple cycles it starts to creep up.

I intend to add a shroud, and have the exhaust manifold ceramic coated, but that is going to have to wait until the two other major projects I am working on are completed.

I guess I am looking through rose colored glasses, but I just don't remember having this issue with the stock 265 in my 56 20 years ago.
 

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My suggestion would be to check the fuel pump. You need a vacuum and a pressure gauge to do this properly. If a pump puts out 6# of pressure, it should pull 6" vacuum. I had this problem on a Ford Pinto. It drove me nuts. I would be driving and without warning, the engine would shut down. Sit a few minutes, sometimes longer, and it would restart. I too thought it was vapor locking. It was sporadic, high speed or puttin' through town. Then a friend of mine told me how to properly check out the fuel pump, Willie Geelhaar - flat rat mechanic from Ashley Chevrolet in Baltimore, Md. He and the dealership are sadly gone. The pressure and the vacuum of a diaphragm fuel pump should be equal. One suggestion, if you do wind up replacing the pump, check it out as well. The Pinto got a new pump and it did not totally cure the problem. I checked the pressure/vacuum on it and the replacement pump was defective as well. Who says lightning does not strike but only once?
 

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The Pinto got a new pump and it did not totally cure the problem. I checked the pressure/vacuum on it and the replacement pump was defective as well. Who says lightning does not strike but only once?


Something to keep in mind these days - new out-of-box is no guarantee. Have seen this more than once.
 

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Discussion Starter · #7 ·
Lots of good questions and comments:

I am running stock ram exhaust manifolds.
The Heat Riser has been removed (I'm in Florida).
The carb has been completely rebuilt multiple times and finally replaced with a reman in my attempts to solve this problem.
Timing is good.
All new fuel lines and fittings, as well as rubber section to gas tank.
Have new gas tank.
Have checked fuel filter and glass bowl for junk in the fuel -- all clear.
Have install a pusher fan with shroud with air thermostat.
The fuel pump has been replaced twice, again -- chasing this problem.

The only things I haven't done are:

Put a temp spacer between the carb and intake manifold.
Wrap or coat the exhaust manifold. -- Is this worth pursuing?
Run a return fuel line. -- I would like to avoid this though.
Recheck the fuel pump pressure -- Although I only have a problem just starting out after a long light when everything is hot -- never while I'm running along.

I just checked and now remember that although I removed the Heat Riser I left the exhaust manifold stove in place. Could it be adding too much heat to the carb? Should I remove it (somehow)? If so, what do I do with the inlet to the thermostatic coil cover on the carb - just plug the hole?

-- D
 

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“although I removed the Heat Riser I left the exhaust manifold stove in place.”

Did you also block off the exhaust crossover passage through the intake under the carb? That is a common over heat vapor lock source. Fel-Pro 1204 Performance Intake Manifold Gasket Sets blocks off the exhaust crossover passage.

If your carb choke stove does not get enough heat after blocking the exhaust crossover you could change to an electric choke.
 

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1955 210 SERIES, 406 DUAL QUAD ENGINE WITH MUNCIE 4 SPEED
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A weak fuel pump is most likely the root cause. A strong pump will over come most fuel boil issues.
 

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A weak fuel pump is most likely the root cause. A strong pump will over come most fuel boil issues.
Carter Mechanical. Cost more but much better that parts store pumps and housing can be rotated.
 

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Discussion Starter · #11 ·
I have blocked of the exhaust cross over ports with the Felpro 1204 -- when I did, the carb body temp dropped significantly.

I don't know if I still have a boil over problem or vapor lock in the line (possibly because the fuel pump is over heating).

I think I'll pursue putting a thermal break between the carb and intake manifold first. Maybe if the carb body temp drops it will solve the problem. This time I'll record some temp measurements with the IR gun before and after.

Does anyone know what I can use as the break?
I'm still using the stock Roch 2GC.
An extra gasket or two, or a phenolic spacer?
Will I need longer carb bolts?
Will it impact the fuel delivery to the intake manifold?


-- D
 

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Discussion Starter · #12 ·
I'll check out the Carter Mechanical and put it on the list of possible fixes.

The order of attack:

1. Carb thermal break,

2. Measure input/output fuel pump vacuum/pressure,

3. Carter fuel pump (if either numbers are bad),

4. Ceramic exhaust manifold -- I still haven' heard any comments about whether this will really reduce the heat generated around the manifold or not. I seen lots of postings about them being pretty, but I'm not looking for cosmetics. Does anyone have any experience?

-- D
 

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Just thinking out loud here. The cross over is used as part of the choke system, no? The exhaust manifold butterfly closes and redirects the hot gases under the intake to make sure the bottom of the intake is hot enough to properly atomize fuel avoiding fuel puddling, bad fuel distribution, fouled plugs and bad running. When the exhaust manifold get to temperature the thermostatic spring butterfly/cross over close off, correct? When the carb choke receives enough heat, the choke opens, the idle screw comes off the fast idle cam and the idle comes down to the correct level. Chevy V8s have successfully run this system for decades. I am not so sure taking it apart and disabling it is the correct way to go. I think the better play is to make sure its actually all working correctly. Even in a hot climate, the motor needs the choke and start up systems to work correctly.

Is you car idling at more then 180-190 degrees?

I would also hang a new fuel pump. They are not all that expensive. Just as an fyi, I had an issue with mine doing something similar. I put an electric pump on it just for emergencies.

Finally, this may be the carb. These carbs are really old now and have been rebuilt who knows how many times by how many people with who knows what skill. Might be time to have a professional go through it and give it a complete rebuild.
 

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4. Ceramic exhaust manifold -- I still haven' heard any comments about whether this will really reduce the heat generated around the manifold or not. I seen lots of postings about them being pretty, but I'm not looking for cosmetics. Does anyone have any experience?

-- D
No direct experience, but I don't think coating the stock manifolds will affect the heat on the fuel system. It was never a problem in 60+ years. It will make them look nice though. :tu
 

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I had the same problem for YEARS on my '56 265 2bbl. The car would act like it was running out of fuel as I pulled away from a stop when the motor was warm. I have completely eliminated the problem by doing the following:

1) Installed a Carter high volume 1965 Corvette fuel pump. I had to reclock the diaphragm to fit properly. Make certain you don't tear the diaphragm or it'll suck air and you'll be right back where you started.

2) Installed a 1/2 inch phonolic spacer between the Rochester 2GC and the intake manifold. ALSO installed a 1/8 inch phenolic spacer the fuel pump and the engine boss. After these two steps, fuel temp in the float bowl as measured by an infared heat gun DROPPED 40 degrees.

3) I installed a $99 plastic fan shroud on an otherwise stock cooling system and fan assembly. The motor runs 180-200 in traffic.

4) Lastly- and this is vital- I use ONLY E0 fuel, NO corn/ethanol/butane gas ever. Cars made in the 1950s were not designed to use E10. Period!

Oh, and make certain the inside of the fuel tank is clean, the sock isn't cruded up and the line from the tank to the carb is new. Run it along the outside of the right frame rail like stock for dual exhaust cars. Mine has duals on it so I did this years ago.
 
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