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02-07-2011, 02:09 AM | #1 |
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Fuel pump oddity
When mounting the fuel pump to my 8CM, the rod seems to be about 1/2" too long because when the cam is as full rise, the pump sits about 1/4'1/2" off the intake manifold. The rod is seated in the receptacle of the pump. Is there something I'm missing here?
I got the engine disassembled but this is definitely the rod and pump that were on it before. The photo does not show the pump raised up but maybe there's something else obvious? |
02-07-2011, 05:31 AM | #2 |
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Re: Fuel pump oddity
Hello Steve Is that with or without a gasket. One or two. It does seem odd that there is that much space. My dad use to use the gaskets (adding more for less fuel pressure) removing them for more pressure. Some of the old carburetors were pressure sensitive.I do not have a fuel pump rod pulled on my 53 8CM so I cannot give you a measurement. Lyle
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02-07-2011, 05:33 AM | #3 |
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Re: Fuel pump oddity
PS the A is my wife's car it is a 29 model the Wife is a 53 model
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02-07-2011, 07:17 AM | #4 |
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Re: Fuel pump oddity
You say that the engine is dissassembled? Is the camshaft positioned properly?
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02-07-2011, 07:51 AM | #5 |
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Re: Fuel pump oddity
The correct pushrod is 10-1/16 inches long. When the lever cup is positioned on the rod you have to push the pump down into position to bolt it. (this is to overcome the the spring preload) Doesn't sound odd to me.
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02-07-2011, 08:24 AM | #6 |
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Re: Fuel pump oddity
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Do not be surprised if when you remove the FP the cup that traps the push rod is smaller than the pushrod. The small cup accomodates the '48 back push rod which is smaller in dia than the 8ba. The other thought is...are you just feeling the resistance of the spring and diaphram? I like to get the push rod at full height then install the pump and stand pushing it down with the heel of my hand until the stand smacks solid on the intake....with a fresh pump there is some resistance before the smack. Charlie ny |
02-07-2011, 08:43 AM | #7 | |
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Re: Fuel pump oddity
Quote:
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02-07-2011, 09:58 AM | #8 |
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Re: Fuel pump oddity
There is also a rod length difference between the aluminum and cast iron intake manifolds. I believe it is a full inch though if memory serves me. Joe
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02-07-2011, 11:02 AM | #9 |
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Re: Fuel pump oddity
Joe that only applys to 48 and older engines.Some one could have mistakenly installed the wrong cup arm on the pump as Charlie said. 49 up has a fatter rod and only 1 length 10+" ken ct.
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02-07-2011, 01:10 PM | #10 |
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Re: Fuel pump oddity
Thanks guys, first please note that in the photo above the pump is sitting flush because the camshaft lobe is down. When up, the fuel pump comes WAY up, probably 1/2". I just didn't take a photo of that when i had a chance.
- The engine is back together and nearly ready to run, so the camshaft is in position. - The rod is a shade over 10" long. - The fuel pump has not been rebuilt yet. Also, I did make sure the rod would fit into the cup in the fuel pump, and the spring is not terribly strong so no problems overcoming it. |
02-07-2011, 02:16 PM | #11 |
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Re: Fuel pump oddity
Ken, Thanks for the correction. Keep forgetting about those NEW flatmotors. By the way, that carb is working great on our 59AB that I put in the 40. Thanks again. Joe
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02-08-2011, 06:24 PM | #12 |
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Re: Fuel pump oddity
Steve,
I am having the same problem with my 1950 8CM and an after market 2x2 intake. My pump with stand won't sit flat even with the push rod in it's lowest position. The rod is fitting well into the FP cup. I don't know what the problem is. I hope we can find out here. |
02-08-2011, 08:53 PM | #13 | |
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Re: Fuel pump oddity
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02-09-2011, 12:20 AM | #14 |
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Re: Fuel pump oddity
My intake is labeled 8CM, same as the block, so I know that isn't my problem. But darned if I know what IS my problem! I'm not comfortable just cutting down the rod to fit. It came with this engine so it should work!
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02-09-2011, 04:22 AM | #15 |
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Re: Fuel pump oddity
with a straight edge across the stand mounting behind the push rod You turn the moter over,The rod should move up just over 1/4 I think 2 tenths of a inch which reflects the pump cam size on the cam shaft .You can mark it with a marker,The amount the rod is sitting above the manifold ,at its lowest point should be the same length as the mounting flange to your pump cup , you can check this by putting something like a screw driver in the cup of your pump and push it to take the slack out from the light spring.Then mark it with a marker .
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02-09-2011, 06:44 AM | #16 | |
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Re: Fuel pump oddity
Quote:
You don't have a problem if all the parts are the same as you removed them. |
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02-09-2011, 09:19 AM | #17 |
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Re: Fuel pump oddity
51-MERC-CT,
It is an Offenhauser for the latter block. The engine was rebuilt before I bought it. The push rod is new, pump and stand are old. Are the 8CM and 8BA pumps interchangeable? DK |
02-09-2011, 10:47 AM | #18 |
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Re: Fuel pump oddity
Steve,
I've been following this thread and wonder.....have you tried another pump? I'm guessing from afar that cutting the push rod ain't such a good idea. Charlie ny |
02-09-2011, 11:59 AM | #19 |
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Re: Fuel pump oddity
Charlie,
I am thinking the same thing for my situation. |
02-09-2011, 12:52 PM | #20 | |
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Re: Fuel pump oddity
Quote:
The 8BA pump will work in place of the 8CM double pumper. ( that's what I use) Something to try- Turn the engine to #6 cylinder TDC. Lining up the rotor to the cap is close enough (this puts the fuel pump pushrod at it's lowest point making it easier to install the pump) |
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