Stroker396@APF

iTrader: (18)

I did a search and read many threads but could not find the answer I was looking for.

I like many before me did a cam swap and am now having the sewing machine valvetrain tick/noise.

But what I don't understand is that sometimes it runs quiet and then it will get loud sometimes real loud and then it will go away. Of course I could never find a spot to pull over when it is at its peak. Then the noise goes away or is faint when I go to check. I keep thinking that one of the valves is not getting oiled properly and this is going to eventually cause a major failure of something. Oil pressure is fine though.

I pulled the driver side valve cover and all the rockers are on straight and tight, my thought was maybe one did not get fully tightened down.

Then I was thinking that there might be an air pocket in the oil system, but I read nothing abut anything like that.

The cam is a decent size 233/236 .595/.592 114

I did read about pushrod length and proper preload and am now wondering if that 7.4" rod length could be the issue.

Any advise or thoughts on this well worn subject are appreciated.

Viper

iTrader: (6)

Buy an adjustable pushrod and measure; it's truly the only way you will have peace.

LS1-450

iTrader: (33)

During the swap did you change from stock rocker arms to roller rocker arms? My roller rockers sound like a sewing machine on steroids. Did the whole check & re-check, even went to a bit longer push rod (even though I had done the initial set-up correctly, length checker & all). Longer push rod experiment only resulted in confirming that the initial push rods were correct. After that, I tried adding more pre-load. A tad quieter on start up, but, same noise while driving. Went back to initial pre-load as well. Bottom line, in my case, is that the rockers are noisy, that's it. Am thinking that it's the needle bearings.

Also, your sound changes may be due to lifters pumping up once oil pressure builds. Usually, the rockers will be louder @ idle than @ higher RPM's. Am not discounting the fact that you may actually have used a push rod that it too short. Just wanted to post the results we had even after quadrouple checking the valve train set-up. Good-luck

Stroker396@APF

iTrader: (18)

Thanks Guys.

I was going to check with Isky and find out if they used a smaller base circle first before I did the pushrod length checker. The springs I swaped in were comp 918's. I am still using the stock rockers.

It is not louder at idle. It will run fairly quiet for a while and get louder out of the blue and if I keep running it will eventually quiet down again, which is what lead me to believe it was an oiling issue and suspect that one of the rockers might not be fully tighened down and possibly twisting ever so slightly.
But the noise when I could hear it was definitly more on the drivers side and I checked those rockers. It also seems like all the rockers are getting oiled, but I am wondering if that could be deceiving as it is an intermitent and they could be drying up intermitently.

The car just rolled 50K, so I don't think the lifters should have an issue.

Anyway, I have a 224/230 on 112LSA in the black car and this cam was an experiment to learn more. It may be a bit big for a DD, but that is a separate issue.

LS1-450

iTrader: (33)

If they are the stock (non-adjustable) rockers, then it's a pushrod length problem. I wouldn't drive the car anymore until it's corrected.

Stroker396@APF

iTrader: (18)

Well I ran the car hard today. And i think I may have peiced together one posible cause of the problem.

My one buddy asked if i had an exhaust leak, which it kinda sounds like and with the extreme vibration at idle and they dyno runs may have shook something loose in the exhaust. I can hear it banging occasionaly. I am going to check everything tomorrow. It was much less today, but as i would listen to it, the sound did seem to be just a shade off timing wise when I put the clutch in with the revs.

Well, I am going on hunt for it.

DaddySS

Loose plug wires, exhaust leak, loose plugs, etc. can all sound like tapping. Intermittent oiling issues to rockers or lifters are very rare and unlikely. Give it a thorough check over, you'll track it down.

Stroker396@APF

iTrader: (18)

Thanks, I just remember this sound well from an 84 firebird. It was the last sound before the engine needed to be rebuilt, so it had me real concerned at first.