340 lifter and rocker arm question

[Whitehatspecial]

I have a 340 engine which was recently (within 8 months) rebuilt using a hydraulic Comp Cams cam and lifters. I used a local engine builder and had the orig iron 340 heads redone. installed new adjustable Mopar ductile rockers, shafts, and cupped pushrods.

I've had tuning problems (running rich) and clacking on startup. Tonight  I decided to pull the valve covers to check the valve adjustments. Sure enough many rockers where adjusted very loosely.  I re-adjusted them using the " adjust exhaust valve when the intake opens, etc." method. Some pushrods seemed to stop spinning almost immediately when I turned the adjuster in and others seemed to tighten up more gradually.

When I was through the car was quieter but I noticed than several (about 5) of the adjustable rockers have much less threaded part showing (about a 1/4" of thread vs. 1/2" on the rest. Does this mean those lifters are collapsed or failed? How can you tell if the lifters are bad? Thanks.

[Chryco Psycho]

That is what I would suspect ,the ones where the pushrod goes tight slowly & ad more adjuster is showing are collapsed

[matt63]

This is an interesting topic.  I noticed that I can adjust the lifters and then go back and find them loose again.  I assumed that they bled down after adjusting them and rotating the engine so I didn't worry.  Surely the springs in them hold very little tension. To be sure you should be able to see how far down the lifter plunger goes ie it should only be 0.060" max down.  If it's more than that there is a problem.

[SuperDave]

I would recommend reviewing the adjusting instructions with the cam builder.  Run the car hot, pull the covers, loosen all the rockers, then start over.  It seems like you may have over tightened some of the valves.  This is evident with the start up clatter, (some are loose) and the amount of thread (some are tight).

[moper]

I've seen some ugly "performance" valve work lately. But 1/4" of adjuster seems excessive to me. Instead of using the "roll it between your fingers" routine, I would pull the intake off, inspect the cam lobes, and set the preload on each cylinder properly. With a hydraulic cam, it should not need that much adjustment if things are done right, and tightened properly. Maybe once a year. The tappets used on the HL cams may be slightly noiseier than a typical hydraulic. This is normal. Trying to adjust out the noise can result in damaged cams. The time to look is before all the iron dust runs thru the engine.

[Whitehatspecial]

I readjusted the rockers today, this time with the engine cold. I saw a more uniform thread count on the adjuster screws and the car is running great finally with minimal valve train noise.


I also finally got rid of the BG Speed Demon      I've been trying to make work for 6 months in favor of a Edelbrock 650. Should have listened to others that warned me about those BG carbs