Fuel pump push rods

M

mountstimothy0

Senior Member
Being a beginner flathead builder, i have a question with fuel pump push rods. It is been told to me that with cast iron intakes it takes a longer push rod for cast intakes and shorter fuel pump push rods for aluminium intakes is this true? And can anyone tell me the lengths for each one. I have one aluminum intake for a 46-48 flathead engine and a cast iron intake for another 46-48 flathead engine. Thank you for any knowledge from any and all flathead experienced Barners is greatly appreciated! Thank you. Tim

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This is an excerpt from early parts book.
 

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mountstimothy0 said:
Being a beginner flathead builder, i have a question with fuel pump push rods. It is been told to me that with cast iron intakes it takes a longer push rod for cast intakes and shorter fuel pump push rods for aluminium intakes is this true? And can anyone tell me the lengths for each one. I have one aluminum intake for a 46-48 flathead engine and a cast iron intake for another 46-48 flathead engine. Thank you for any knowledge from any and all flathead experienced Barners is greatly appreciated! Thank you. Tim

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Click to expand...

Yes, true, as 51 Merc shows.
I found out the same way as you are doing now. Fortunately , I had pushrods of both lengths. May still have some ?
 
There is an inch difference in the lengths of the push rods, so it ought to be obvious which is the right one for your engine. My experience is that they can benefit from fine tuning of the length. They should be made from a tubular centre with pressed in ends. It is possible to pull the ends out and insert washers to get the desired length. The washers need grinding down afterwards to get the diameter down.

Not too sure about your fan belt. Is that stuff rated for the speeds and longevity you will need?

Mart.
 
Hasn't someone fabricated a 'fuel pump substitute' taking their fuel pump up and down measurements from the mounting surface to the bottom rod surface while turning the engine slowly for max and min? Taking these measurements which are transferred to the 'fuel pump substitute' would a true proper measurement for that engine?
 
This is a old post I posted some years back on the old FB it might be helpful .
You can check the cam travel by placing a card behind the push rod mark it at its lowest point and at its highest as you crank it over this measurement can be used to check the gap under the oil filler tube and pump, it should be about 2/10". The rod can be ground off at the top if the rod is to long or if the gap is less than 2/10” you can build the rod up with weld . . Most of the ware is often n the linkage, and this can compensate for some ware. Service info specify min 10 thousands minimum ware on the rod this measurement can fluctuate depending on what gaskets you use some after market manifold or pump Gaskets are likely thicker than original stock ones also the pump mount bolt holes can be loose . The way to set the height and allow for this is with the pump on the top of its stroke with your hand on the oil filler apply light pressure down on the pump to compress the small spring on the linkage and remove the play, (not the Diaphragm spring) then check the gap from the pump gasket on the face of the manifold to the lower flange on the oil filler tube this, Should be the same as your card or 2/10 “.Ted
 
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FlatheadTed said:
This is a old post I posted some years back on the old FB it might be helpful .
You can check the cam travel by placing a card behind the push rod mark it at its lowest point and at its highest as you crank it over this measurement can be used to check the gap under the oil filler tube and pump, it should be about 3/10". The rod can be ground off at the top if the rod is to long or if the gap is less than 3/10” you can build the rod up with weld . . Most of the ware is often n the linkage, and this can compensate for some ware. Service info specify min 10 thousands minimum ware on the rod this measurement can fluctuate depending on what gaskets you use some after market manifold or pump Gaskets are likely thicker than original stock ones also the pump mount bolt holes can be loose . The way to set the height and allow for this is with the pump on the top of its stroke with your hand on the oil filler apply light pressure down on the pump to compress the small spring on the linkage and remove the play, (not the Diaphragm spring) then check the gap from the pump gasket on the face of the manifold to the lower flange on the oil filler tube this, Should be the same as your card or 3/10 “.Ted
Click to expand...
I only have .200 cam lobe travel, should I get a new cam?
 
Mart said:
There is an inch difference in the lengths of the push rods, so it ought to be obvious which is the right one for your engine. My experience is that they can benefit from fine tuning of the length. They should be made from a tubular centre with pressed in ends. It is possible to pull the ends out and insert washers to get the desired length. The washers need grinding down afterwards to get the diameter down.

Not too sure about your fan belt. Is that stuff rated for the speeds and longevity you will need?

Mart.
Click to expand...
Yes the fan belt is rated for the speed and longevity that i need. Whats nice about it is if it was to break all you have to do is change a link. My dad has had one on his 29 ford open cab truck for 9 years. Thanks for your concern though

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mountstimothy0 said:
Yes the fan belt is rated for the speed and longevity that i need. Whats nice about it is if it was to break all you have to do is change a link. My dad has had one on his 29 ford open cab truck for 9 years. Thanks for your concern though

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Click to expand...
Sure should work well in an automotive situation.
Using one on a lathe where in order to change the belt the machine has to be taken apart. Saved a lot of time and grief.
 
My mistake 2/10 ,Been on metric to long

I only have .200 cam lobe travel, should I get a new cam?
 
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On manifolds: The aluminum short/iron long rule is generally true but not 100% so on Ford manifolds. On aftermarket, about everything is aluminum and both of the '35-48 heights can be found. SIMPLE way to sort, wish i had exact numbers written down, but since there are only two common choices this is plenty: Measure from the bottom of manifold casting at the rear edge to the machined flat where the fuel pump stand lives. If that is in the general neighborhood of 1" it needs the short, if in the general neighborhood of 2" it needs the long. Once you notice this you don't need to measure...you should be able to tell just by eyeball. '49-53 manifolds are all one height. if you need to use one on an early motor they are correct for early long pushrod. If you are disguising a late motor as an early so it will look right in a hotrod or race car, you can convert the block for early pushrods by installing the early bushing directly into the late bushing.
Up front on earlies the stud to mount generator/fan to manifold comes in several heights, enough different to require different fan belts. Aftermarket manifolds also vary there.
 
FlatheadTed said:
My mistake 2/10 ,Been on metric to long

I only have .200 cam lobe travel, should I get a new cam?
Click to expand...

Disconnect the fuel line from the carb and into a jar. Crank the engine (with the ignition off and/or coil disconnected) and see if each rev gives a decent spurt of gas. If so, press on. The other test is a fast run up a long hill; if it starts to sputter and miss, your pump may not be keeping up. In either case, I would install an electric fuel pump before I would go through the pain and expense of changing out the cam.
 
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