331 Cadillac engine question

I'm installing an electric fuel pump on my 54 caddy and rerouteing fuel lines to see if I can remedy my vapor lock/hot starting issue. So I'm removing the mechanical pump all together. Question is, can the pushrod that activates the pump lever be left in place or does it need to be removed also. It doesn't seem like it would go anywhere (doesn't move if I tug on it). May be a dumb question, just didn't want to cause a problem later on. I have a block off plate ready to got in the pumps place.


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You need to remove it or fix it where it will stay up and away from the eccentric or it will make noise and beat the lobe it rides against until it's useless. You may want to use it again in the future. Easier solution is to wrap the fuel line with something to insulate it if it's vapor locking.

 

I gotcha tx turbo, the way these fuel lines are routed from the factory are directly in many hot spots, front of block ,water pump and under oil pan. What about leaving the mechanical pump and just plugging it? That pump is just in a very hot spot . I'm guessing after shutdown it's cooking the fuel and pressuring it , has nowhere else to go but the carb and flooding it. Was planning on routing a new hard line from the back of the carb directly to the drivers side then down to the frame rail.


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You can do that. Are you sure it's flooding the carb? Vapor lock is when the fuel in the lines boils and then the pump can't pump it anymore and it dies like it ran out of gas. If it's just hard to restart when it's hot, that's usually because the carb is hot enough to boil the gas out of it. The fix for that is to put an insulator under the carb and block off the exhaust crossover.

 

That pump was there stock and I doubt that the pump is actually your problem. that said if you plug it off it will eventually develop pressure or suction depending on how you look at it and blow the diaphragm. If I were going to leave it I would just leave it and not block anything off at all. That is a little bit back yard though the best thing is to remove the pump and the rod and ad a block off plate. That is what I would do if it were mine.

 

On my 49s i plumb in an electric pump back by the tank and wire it to a toggle switch. When it occasionally vapor locks, flip the switch. Leave the mechanical pump functioning as normal. Test flow the electric pump to be sure it will p*** gas when it's not activated. Some do, some don't. Loosen the intake bolts a bit, pry it up on each side and slip in a very thin, tin can thickness, metal shim to block the heat riser p***ages.

 

It's the primary's that look wet with fuel after shutdown. The engine runs great no problems in that department. You can immediately start it just after killing it. Just if you wait 10-15 mins it just cranks and eventually starts. Just like a flooding situation. I have an insulator on it(from dash mans hot rod parts) and crossovers are blocked. Heat risers are deleted also. Also, carb bowls are full of fuel and so is acc pump in this situation . Inside carb is clean as a whistle. Maybe a 6 month old carb at most. I reset floats lower than stock specs also(2and1/4)


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I agree, just pulling my hair out over this thing. I would love just to leave as is but at a loss on what to do


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Do you pump the throttle when you try to start it hot? Worst thing you can do. Open slightly so some air can get in there and crank, no pumping.

 

No , I never pump it in the situation, usually after about 5-10seconds of cranking it fires stumbles and clears up and runs as usual. Just afraid of gas getting in the oil. Pull the dipstick but didn't get any gas smell


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sounds like carb droolage. what do the plugs look like? tan color? black?

 

"carb droolage" Now that's a technical term I have never heard before, Love it!

 

Haven't pulled a plug yet,guess I should have by now. I'll check that out this evening. I do also notice a little gas weeping from the main gasket that goes around the tops of the bowls. Just kind of stained looking on the outside of the carb.Not sure if all the 4gc's weep a little. Was thinking of lowering the float level even a little more but didn't want to starve it out.


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Yep-I would agree your issue doesn't sound like vapor lock. If you are really flooding , something is leaking in the carb and letting the float bowl drain into the engine. If you have no gas when you try to start, the gas is boiling out of the float bowl, and you need a insulator between the carb and manifold. Vapor lock usually occurs when the engine is running and stalls it.

 

I think this was said but I just want to point out that removing the rod that actuates the pump is fine if you delete the pump. Other wise it would cause some issues..

Carry on

 

I have a spacer between the carb and intake. Fuel levels in the bowls look like where they should be. I've pulled the top half of the carb off when hot to check.


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Is your bowl vent working?

 

I thought about that also, though I haven't really checked them. I figured they should be working properly being a newly rebuilt carb. I purchased the carb from Carb-x .i have bought a few other carbs from them with no issues, but that doesn't mean this one may not have issue


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I would check it. When I bought my 63 it had a rebuilt carb on it from a commercial rebuilder in Dallas. I had to readjust all the linkage and reset the floats.

 

Sounds good,I'll pull it off and check all the necessary things. I'm guessing the vents can just be blown out with compressed air? According to my manual, the float drop should be measured at 2 1/4 in. I currently have the drop set at 2 3/8 to lower the fuel level. Should I go any lower than that?


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float drop is how far they hang free. float level is adjusted by bending the tang that contacts the needle valve.

 

Holy ****. I feel stupid now, never adjusted the level just the drop. I must have skipped that part in the manual . Maybe my problem, the bowl is being overfilled. Hey, I'm a body man. I'm real great at pounding on metal, no so good at engines. Thanks for showing me the light sir!


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The vent I'm talking about is a little cap that is connected to linkage. It opens when the throttle is closed. I'm not sure if the 54 had it yet....but my 56 has it.

 

Well according to the level adjustment in the manual I'm pretty far off. Would this be causing my flooding issue?
I'm just a hair over 1 3/4, should be 1 19/32 or 1 5/8 would be close enough


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An electric pump is not a bad idea because of the high pump placement on the Cadillac like the flathead. I would check for fuel dripping off the booster in the carb after it is shut off. If that's the case it could be the needle valve or fuel getting hot and expanding when the engine is off and over powering the needle valve.

 

Set the float level correctly-could be part of the issue. Or could be other issues like sunbeam suggests. When setting the float, carefully examine the needle and seat for any issues.

 

Well I finally got the problem solved by adjusting the floats, there was way too much fuel entering the bowls. Which explains the lower portion of the carb being soaked with fuel all the time. I also ran new hardlines and got rid of the rubber hose fuel lines. I did a temp check on the lines before and after with my laser temp gun and the hard lines are so much cooler than the rubber. About a 20 degree difference after shutdown! Thanks for all the help fellas. Now I'm still running the stock pump and didn't have to deal with an electric pump.


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Good deal...

 

Txturbo. I have an electric pump from jegs on my 53 caddy. I want to take it back to mechanical. I can't stand the whining noise the electric pump makes! I found a vacuum pump or a dual action pump. What is the difference and which one would mine need?

 

I added a electric fuel pump to my 53 Caddy because of vaper lock issues. No problems since i made the change.