Been fighting this rattle since about 30 mins after putting the new motor in 3 months ago.

Here's some history:

Did a cam swap last year. The mechanic put too much lash in the car. 30 thousandths clearance between the rocker and the valve. Needless to say it destroyed my valvetrain and eggshaped my valve guides.

So this year I rebuilt the motor and changed everything but the rockers, springs, and the lifters. Put the top end together myself with an AFR REV kit.

The problem:

When I first turn on the car or when I shut off the car there is a rattle (not a tap) that comes out of the intake or passenger side valve cover. Sometimes it lasts upto 2 seconds. Tried a much thicker oil and its still there. Motor has less than 200 miles on it and hasn't seen more than 3000 rpm. The car also will bog or idle very low to the point where it sometimes will stall.

The rattle is less noticable or nonexistent at 2000rpm and above. Car seems low on power.

Bad lifter?

 

Did you use Comp "R" lifters?

My buddy used those in his motor and destroyed 1, busted clips out of 2 and buckled/cracked the clips on 5 or so more. I dont think he even ran them for a year and never beat on the car very hard.. his cam was the XE230/236 so nothing too extreme.

 

Yes they are Comp R lifters.

 

Any other opinions?

 

the new make of comp r's are known for problem, but i heard that if they are bad, then they would have problems right away, and not 5k miles later??

 

WHat would be a better choice of lifter?

 

Grip: I assume that you installed new valve guides. As you are keenly aware the top end is quite simplistic and at the same time all of the components need to be compatible and working.

So I assume that your push rods are hardened if non-sa RRs, that your springs are adequate + for your cam, that your quideplates fit nicely and your adjustments are according to specs for the lifters.

So, being that you are one of the smart ones, I'd pull the valve cover and check it out, noting what is happening when you first start it up and at various RPMs.

Could be a lifter, but check it out. Also, if you are using really thin oil, mabe it is just bleeding down too quickly and perhaps a 10W dino might helpl in that case. Good Luck.

 

You assume correctly.

I'm just wondering if a bad lifter would pull the idle down?

 

Don't think it's a lifter. I'm the self professed lifter tap expert in my house from experience. Usually lifters tap. Rattle could be a sign of something more serious like bearings. Get a mechanics stethescope and try to locate the sound. If it's your lifters you'll be able to hear it loud while on the valve cover bolts.

 

Seems like a rocker is overly tight that it could pull the idle down and perhaps the lilter is not bleeding down at all i.e. the rod is pushing the lifter tight against the lobe without any give thus slowing the idle. Does that make any sense at all? I'd push down on each rod and see which, if any is either too easy or really hard to depress. If you have Comp lifters, I understand there is little or no lash so it just might be one that is too tight. Get on it.

 

Seems like a rocker is overly tight that it could pull the idle down and perhaps the lilter is not bleeding down at all i.e. the rod is pushing the lifter tight against the lobe without any give thus slowing the idle. Does that make any sense at all? I'd push down on each rod and see which, if any is either too easy or really hard to depress. If you have Comp lifters, I understand there is little or no lash so it just might be one that is too tight. Get on it.

 

Hmm. I did try to re-lash the valves after the rattle started. I found a couple of rockers that were loose. Maybe the lifter had collapsed and me re-lashing it tightened it down too much.

I'll try re-lashing it tonight and if it still rattles I'll order a set of new Comp Rs. Thanx Bubba.

 

if u have beehive springs u can use stock ones without problem