The SAGA Begins - '66 300 Convertible

[Big_John]

the wear on the rod was exacerbated

The 12 year old boy that still exists in my old body just giggled at that.

In my case, I think the wear on the rod was exacerbated due the use of an old rod on a new cam lobe. When my engine was rebuilt, the cam was replaced, but not the rod.

I've been wondering about that... I've never changed one when I've done a cam. I always coat them in "moly" cam lube though. Can't say I've had a problem.

The lower pressure of the fuel pump spring versus a valve spring has me thinking that it shouldn't matter... But then if it does wear, what does it do to the cam lobe? The lifter has a little over 5x the surface area but if you do some math, the amount pressure per square inch on the push rod is probably not that much less than the lifter. (I don't know what the spring pressure on a fuel pump is, so I just use 40lbs)

So it makes some sense to replace the push rod... It sure can't hurt!

 

[Ripinator]

My wife doesn’t want to go for joy rides anymore because my rod was too short last summer.
After being stranded along the road for a few hours being less than satisfied, we made it home and I upgraded to a longer rod.
In-line electric fuel pump for emergency fix? 68 Polara.

I feel your pain. In my case, last September we attempted to drive my car to Greeneville, SC for a Chrysler Club, Intl meet. We broke down in Lynchburg, VA where I replaced the fuel pump. Car ran great, but we broke down again in Spencer, NC. I coaxed the car as far as Charlotte, NC where it was finally and totally done. Went on to the meet in a rental. Had to call No. 1 son to come with his truck and a neighbor's trailer and towed the turd back home. I've been dicking with the problem ever since - until I finally discovered the problem rod three days ago. My wife just wasn't into the joy of the experience either. . .

The 12 year old boy that still exists in my old body just giggled at that.


I've been wondering about that... I've never changed one when I've done a cam. I always coat them in "moly" cam lube though. Can't say I've had a problem.

The lower pressure of the fuel pump spring versus a valve spring has me thinking that it shouldn't matter... But then if it does wear, what does it do to the cam lobe? The lifter has a little over 5x the surface area but if you do some math, the amount pressure per square inch on the push rod is probably not that much less than the lifter. (I don't know what the spring pressure on a fuel pump is, so I just use 40lbs)

So it makes some sense to replace the push rod... It sure can't hurt!

This twelve year old boy giggles too. . . My new rod should arrive tomorrow.

 

[Samplingman]

In my case, I think the wear on the rod was exacerbated due the use of an old rod on a new cam lobe. When my engine was rebuilt, the cam was replaced, but not the rod.

I did not replace the rod on my motor after rebuild. I did measure it and seemed withing spec. I remember a discussion regarding new replacement rods as being too short as well, which made me keep my original. I think it was @detmatt that brought it to the board's attention in the first place.

 

[Zymurgy]

In my case, I think the wear on the rod was exacerbated due the use of an old rod on a new cam lobe. When my engine was rebuilt, the cam was replaced, but not the rod.

I never thought about it but basically the same exact thing happened to me. It wasn't long after the push rod needed replaced. Sounds like anyone replacing the cam should go-ahead and replace the push rod at the same time.

 

[detmatt]

I did not replace the rod on my motor after rebuild. I did measure it and seemed withing spec. I remember a discussion regarding new replacement rods as being too short as well, which made me keep my original. I think it was @detmatt that brought it to the board's attention in the first place.

It wasn’t that Ma Mopar’s replacements started out too short but that they weren’t properly hardened and therefore didn’t last very long.
I’m surprised I didn’t pull all of my hair out getting to the bottom of that.