I know this sounds stupid but how tight should the pushrod be?
I’m chasing a fuel delivery issue on my 440. I had a comp cam 4626 in engine. It seems ok but I had already bought another just in case so I figured I would replace it while out. I bought a Mancini MRE5249569. Usually I have to grease the pushrod up so it won’t slide out while installing fuel pump. I can’t even push the new one in. I greased it up and once it gets over the shoulder at the 3/4” mark it doesn’t want to go in without some force. I don’t want to tap it all the way in and then discover this it not right. The diameter of the mancini unit is bigger by .0004. If I’m reading my dual gauge right.
Length wise the Mancini unit is 1/64” longer than the Com Cams unit

It shouldn't be that tight. The spring in the fuel pump might have a hard time keeping the rod against the cam lobe if it's too tight and it could cause premature wear or even lock the pushrod up from friction. Plus at higher engine rpms with it tight you could experience pump cavitation resulting in low fuel pressure and low volume.

Pull it back out, inspect for any burrs, nicks, scratches, etc that maybe causing an issue, polish if up with crocus cloth until it slides in nice and easy like you are used to.

I had to pull it back out with some needle nose pliers. no burrs or nicks. I put the Comp Cam rod in my calipers and spun it around- perfectly round. Did the same to the Mancini unit-it is not perfectly round. Granted I may be splitting hairs here but we are talking about engine parts. And since I have a couple of 440's I had bought two Mancini rods since it's always good to have a spare. The second one is even worse.

This place says they have NOS ones. I never bought from them before. https://www.moparmall.com/MoPar-1737745-1737-745-Fuel-Pump-Push-Rod-p/801-006_a.htm

Or you can get a hold of mccannix who is on this forum. He has or had a supply of them.

https://board.moparts.org/ubbthread...7/re-fuel-pump-push-rod.html#Post2375497

Get one from the member hereMccanix.He has NOS ones that work and the price is right.Had a problem with one I had.Bought his and no problem.IIRC they are like 20 bucks.Well worth it.Rocky

That was an interesting read. Why would Mancini oversize the diameter of the pushrod? Think I'll stick the comp cams pushrod back in for now. At least the car runs, just won't go past 75 without sputtering due to lack of fuel.

They dont manufacture any of the parts they sell.

And the supplier that did obviously has poor quality control.

That's what I'd do.

Used an aftermarket pushrod in my daughters 69 Charger. In 2 months of occasional driving it wore 1/4" and stranded her on the freeway. Don't trust any of the aftermarkets. Got an NOS from Mccannix and alls good.



Mancini related...for same car bought a couple strut rods that didn't fit, longer than stock and too large at LCA end.

You do know how to test if something is hardened don't you?

Now I do.

Thanks for the tip on the pushrods. Contacted Mccanix on Monday, had the new pushrod by Friday. Car runs a bit better but still lays over when I get on it. I'll start a separate thread for that issue.

I'm just an old fuddy duddy , but I don't remember buying speed parts to ever be "Plug N Play".

That issue could be related to that worn pushrod. While the soft pushrod was grinding away it could have been grinding away the camshaft lobe that makes it "push". Now, even with the new pushrod the camshaft may not be pushing it enough to provide full action of the fuel pump. A fuel pressure gauge hooked up and read during hard throttle would be helpful. If the pressure drops below 3.5 pounds, that's not good.

I am not sure that finding NOS rods is a real fix no more than I think that the issue is confined to aftermarket fuel pump push rods. We have fought this problem since the '70s and I have always kept spare fuel pump push rods on the shelf beside my spare ballast resisters. In 2000, I had to change the push rod in my '71 GTX that had the original 80,000 mile unmolested 440. And a couple of years ago, I lent my last shelf rod to a guy at Street Machines for his original 383 Fury. I have probably replaced a couple dozen worn down push rods over the years. Most were OE.