1934 model 40 v8 question

R

Rsb43

Member
My stock (I assume) 5 window coupe v8 with Aluminum intake, I believe needs fuel pump rod replacement. What length is it, and where would you recommend I order replacement?
Also, previous owner put in 8v battery that is now on last legs. Do you recommend returning to 6v, or continue with another 8?
Thank you in advance.
 
An 8 volt battery is just a band-aid to get around other, more basic problems with the electrical system. The best thing to do is use an Optima "Red-Top" 6 volt battery and make sure all cables are of the proper size and that all connections are clean and tight. There is currently a problem with availability of Optima's, but they are out there. See this thread to see where others have been able to find them : https://www.fordbarn.com/forum/showthread.php?t=317347.

A lot of times, the battery cables and ground straps on these cars have been replaced with 12 volt cables from the local auto parts store. These cables are not heavy enough to carry the increased current required by 6 volt systems. Other times, grounds been removed or even deteriorated to the point of non-functionality. 6 volt systems work well if the proper cables are used, all connections are clean and tight, and the wiring in the vehicle is in otherwise reasonable shape.
 
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All good advise above ^^^^ , main thing is big fat battery cables and good connections and then the 6v system works just like it was designed
 
The pump rod is 7.872" long suggest you look at the thickness of the gasket that seals the intake to the fuel pump adapter, if too thick fuel pump pressure will be lowered. I would suggest going to the 6V battery so that you can use original style replacement or NOS parts such as the ignition resistor. Higher voltage will put a strain on the starter motor. How was an 8V battery charged in your car?
 
Terry
There seems to be a discrepancy via a previous post??? It was listed as "8-7/8" here????? Further reading indicates two different fuel pump stands SO depending on which one you have there is a 1" difference??


"your 8.78' long pushrod is the correct one. The statement you have read that states the 7.78 long rod is to be used with aluminum manifold is not entirely correct; depending on the manifold, there is two different heights of the mounting flange for the fuel pump mount, 1" difference between the two. If you had the lower mount style, there is no way you'd be able to assemble the pump in place if using the longer, 8.78" pushrod!!
The baffled ventilation tube affair is vital to have installed, as it directs crankcase ventilation down, through the crankcase, from where it circulates, moving up through the valve chest and exiting at front bottom of block. Without the baffled tube in place, the ventilating air can simply 'shortcut' straight through the valley and exit..."


https://www.fordbarn.com/forum/showthread.php?t=315175&highlight=fuel+pump+rod+length
 
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The quotation cited is not applicable to original '34 engines. They are not ventilated; that feature began with the '35 engines. Further, there was only one fuel pump stand used on '34 V8s, The confusion arises given that the '35 fuel pump stand is different, but only slightly and is easily mistaken for the '34 version (and vice versa). Both are the same height.

It is the manifold itself which determines the length of the fuel pump push rods. Given that the two possible lengths for the rods are roughly an inch apart, it is nigh on impossible to mistake one for the other. What is in your engine now and by the way, wearing out a fuel pump push rod is not common place? What leads you to believe that the rod needs to be replaced?
 
Car sat except for a yearly run for ten years. Prior was driven less than 25 miles a year since 1982. When I pulled it out for garage, mice haven and old rotted Inside the gas tank. Replaced carb, fuel pump, fuel line and gas tank. New distributor, wires, and wiring harness. Seems like car starves for fuel when foot to the floor, but is 90% rectified when I adjust choke, so I assume gas/air mix is heart of issue……everything else is new and triple checked, this is cheapest option of fixing it…..after that I’m pulling heads and looking for stuck valve etc…….I appreciate your advice, I couldn’t make heads or tails of the two different size rods.
 
I'm with David, it is really rare to see a worn fuel-pump pushrod as the cause of a fuel delivery system issue. My bet is that if it was running with the current setup, the pushrod is not your problem. It can easily be an issue with the pump itself or the short flexible/braided line between the hard line and the fuel pump (sucking air) or another line/tank issue.

Give us some history on the engine and the problem you're trying to fix.
 
Car sat except for a yearly run for ten years. Prior was driven less than 25 miles a year since 1982. When I pulled it out for garage, mice haven and old rotted Inside the gas tank. Replaced carb, fuel pump, fuel line and gas tank. New distributor, wires, and wiring harness. Seems like car starves for fuel when foot to the floor, but is 90% rectified when I adjust choke, so I assume gas/air mix is heart of issue……everything else is new and triple checked, this is cheapest option of fixing it…..after that I’m pulling heads and looking for stuck valve etc…….I appreciate your advice, I couldn’t make heads or tails of the two different size rods.
Entire fuel system replaced, lines, pump tank and carb.
 
What is the exact fuel pump you have replaced the old one with ? I have come across several new reproduction 36 type pumps which have a non original design linkage on them which have too much free play and therefore take up all the push rod movement without actually moving the pump diaphragm. New made in China and completely useless. Better to rebuild an original Ford AC type pump by fitting a new kit into it. You cant just assume by fitting new reproduction parts they are going to work correctly because much of it is just junk. To check your fuel pump flow just remove the outlet pipe on the pump and crank the engine over on the starter and note if you have a good flow. The original stock aluminium 34 intake manifold uses a pump push rod 7.872 inches long. Any variation in parts fitted at a later date such as intake, pump stand etc could change this . Regards, Kevin.
 
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