flathead fuel pump pushrod too long?

S

Scottyboy

Member
Help! Test fitting my fuel pump on my 52 8BA flathead rebuild and the pushrod seems about 5/16" too long? It is 10 1/16" standard length. I put an Isky Max 1 cam into the engine otherwise everything else is stock. The fuel pump is the vacuum pump. Not sure what is going on. Thank god the cam lobe was up during my test fit.... Could have been ugly. Anybody ever had this problem?
 
What intake manifold are you using? There is only the 10 1/16 pushrod for the 8BA. Are you sure the pushrod is fitting in the cup on the fuel pump?
 
The cam may have a larger base circle on the fuel pump lobe. Is the cam something other than 8BA? If it has the distributor drive on the front then it's 8BA family. The Manifolds are different as was mentioned. Aftermarket manifolds have to be scrutinized for the fuel pump mounting.
 
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It is the stock manifold with an Isky Max 1 cam. You might be on to something though. I tried a different approach to make sure the rod is in the cup. I mounted the base first and then tightened the pump to the base. I can get it to tighten up with a little muscle. The pump lever is definitely topped out with zero tolerance. The cam is in the up position.t Do you for see any issues at fire up?

thanks
 
If you can calculate the exact dimension you need, you may have to make a shim for the pump stand that gets you back in the ball park. I sure wouldn't want to break a good fuel pump or bend a good push rod. Stack some more gaskets under it if it's close.
 
If the rod won't work, something is wrong, and it probably isn't the rod. Might as well find what the problem is instead of trying the band aid approach. With the pump out, does the rod fit in the cup. I always install the pump to the housing and then install the assembly. If the cam is on the lobe, the base will stand proud about a 1/4 inch.
 
The ends can be separated fairly easily, however that would be my last resort. Again look for the problem.
 
Are you expecting the system to go together without any tension to be overcome? If so, your mistaken. You should expect to need to depress the spring and diaphragm somewhat in order to get it together. I agree with flatjack9, don't modify the rod yet. Figure out what's going on.
 
I'm with Flatjack here, the pushrod dimension you gave is what it's ment to be. Something else is throwing stuff off. Find that and fix it.
But do report back with your findings, always good to know what's going on and what the problem is/was, could be of help to others.
5/16" seem a lot of wrong, you say stock manifold, iron 8BA? What fuel pump stand? What pump, you say vacuum, but is it stock Ford?
The cam, is it ground by isky on a new core, or reground on a stock core?
lots of questions I know, lots of answered questions help pin down the problem.
I do feel, in contradiction of what I first said about fixing the actual problem, that if it's the cam that's the issue, if it were mine, I'd shorten the pushrod, rather than change the cam. 8BA pushrods are 3 pieces pressed together lightly, they seperate quite easy with a bit of a twist.
Martin.
 
Russ/40 said:
Are you expecting the system to go together without any tension to be overcome? If so, your mistaken. You should expect to need to depress the spring and diaphragm somewhat in order to get it together. I agree with flatjack9, don't modify the rod yet. Figure out what's going on.
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Also good point, the vacuum spring is damn strong in comparison to the fuel pump spring.
Martin.
 
If the cam is in the up position then the pump would have pressure on it. Isn't 5\16 about the travel to get the pump to work? Turn the engine until the came is down and the pump will bolt on. Maybe I'm missing something here!
 
4tford said:
Is the rod going all the way to the cam or is it stopping at the cam bearing??
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That happen to me!!When I put the bearing in to far the hole in the bearing was to the back just enough to keep the rod from passing thru!! took the oil pump gear off at the back and used a old bearing to tap the cam bearing to the front with the cam still installed!! Pete
 
+2 on the cam bearing in to far, make sure the push rod is riding on lobe. The lobe lift is .200 make sure the rod is going up and down, make sure it's on low cam when installing the pump. Walt
 
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