I've had a loud tapping coming from the front for sometime now. I finally figured out how to take the pushrod tubes apart and looked at the rods in prep for replacing what I thought was the culprit - a bad lifter. Well after popping the tubes apart, I spun the rods while unloaded. The front exhaust rod felt like it was binding as it was spinning around, and by look and feel it seemed like the rod was bent as the tube was moving back and forth slightly while I was spinning it. I took the rest of the tubes apart and found that, while they didn't feel like they were binding, the tubes felt like they were moving back and forth like front exhaust, all except for the rear intake.

Of course I on't know for sure until I pull them and look at them on a flat surface.

So a few questions....

Could the rods be straight and moving the tubes like this somehow?


Do bent tubes usually indicate bent valves?

I can't remember if the noise started before or after I painted the gear case cover, but when I took that off, I did not unload the cam - not knowing I was supposed to do this. The cover seemed to line up perfectly when I put it back on though. Could this be the reason for the bent rods?

Could swapping the rockers from front to back have caused this?

 

I am not near smart enough or experianced enough to answer all your questions but from my experiance I can answer a few.

Bent rods don't necessarly mean bent valves (mine didn't).
To my understanding bent push rods only mean that they were adjusted too tight.
When I first put in my cam a mechanic I had helping me stressed the importantce of putting the rockerboxes and rockers back in the same place they come from. Not sure why but he told me it was important.

I think if I were you I would simply buy a new set of pushrods and put them in.
That is all I did for mine and she is still running fine.

 

I'm just hoping I can get away with just a new set of pushrods and lifters. When I painted the gear case cover, I also had the rockers boxes painted. The paint place pulled off the markers I had on them so I'm not sure if I put them on the right jugs or not.

 

Are you using adjustable pushrods? In my experience, I've often found "bent" pushrods right out of the package, as many of them aren't brazed together straight, and will wobble once put into service.

I had to sort through two sets of Screamin' Eagle pushrods to find four straight rods when I installed adjustable rods. When I put the first set in, I had a "bent" pushrod in the front exhaust position that caused a tube wobble so bad that I had an intermittant leak at the bottom o-ring. Since adjustable rods are thicker than the stock pushrods, it's vital that they be straight, especially the front exhaust position, to prevent the rods from rubbing the inside of the pushrod tubes.

If possible, install the pushrods between centers on a lathe, and check them for runout (straightness) before installing them. If you don't have a lathe, you can use two straightedges and lay the rods between them and roll them to check for runout.

 

I think you will be fine. I'm not sure you need new lifters but what the hell it can't hurt. Just make sure you get some good pushrods. Ther first ones I put in were chrome moly and I bent all 4 (probably my fault). The second set were screaming eagles and I couldn't get them to adjust for anything and finally had to have a shop do it but they have been going strong for around 10k miles now.

Good Luck

 

You can swap the rocker box components about as much as you like, they don't have to be where they started out but its good practice to always put things back from whence they came :-)

 

Also through doing some reading I heard that removing the rocker boxes and replacing them while the valve springs are still compressed can cause them to bend. Never knew that. I've taken those boxes off about 3 times now over the years and never paid attention to engine position.

I guess I'm really just concerned with how it happened in the first place. Did I cause it through gross incompetence, or did something else cause it. Anyway, pulling them tomorrow or tonight and check the rods and the lifters and the rocker covers and all that jazz. I checked compression tonight and it was within specs for the manual at 100psi so I don't think I have bent any valves yet.

 

100 psi is low. My 80 ci runs at 180 each cylinder after I re ringed it & lapped the valves.
If your on a budget & need a set of stock push rods, I will mail you mine. Their fine, I went to adjustable so I could do cam work without pulling the box's!
Hatch.

 

The manual states that as long as the psi is above 90psi and less than 10% variance between the two it is in spec. They were both almost exactly 100psi.


I'm going to take the rods to a garage today and see if they can measure the run out. They looked bent in the tubes, but I can't tell now.

Also, I have two different numbers of pushrods. One number was in the exhaust, and one number for the intake. I'm guessing that is normal?

I also took a look at the lifters. They looked fine to me, except the one which I thought was making the noise anyway, and it had a VERY minimal amount of play in the roller. All of them had a little lateral movement in the rollers, but the possible trouble maker had some up and down movement. Anyone know the acceptable play in rollers?

 

You can check your tappet rollers by holding the tappet in one hand and using the other hand to try and move the roller up/down...Rotate the roller a few degrees and check for up/down play...Do this for at least one rotation of the roller..There should be no up/down movement on the roller-shaft...

I've replaced countless tappets on the 'ol 900 and one of the tell-tale symptoms is an intermittent loud clatter from the valve train...At times I had to rotate the roller 270-degrees before finding the bad spot which was a broken needle-bearing between the roller and roller shaft

The factory spec for MAX side play (or Roller End Clearance) is .015".