I was using comp r lifters but after hearing all the comp r stories I figured that mine were causing problems. Low and behold I was right. I pulled them out last night and there were dimplies in the plunger retainer rings from the pushrod hitting them. Luckily no clips were missing. That was when they were adjusted with the car warm and 1/16'th past 0 lash. I swapped in some used stock lifters that I cleaned thoroughly and when I started the car last night (after some initial clacking) I was pulling 16" vacuum at cold idle!!! Problem solved. The car ran greater than ever... I know this because on my second WOT blast my clutch roasted like I was standing still with my foot on the brakes. In any other case I would be pissed about the clutch but I wasn't.

Next part of the story... It ran awesome last night for about 20 minutes but I noticed that it got a little sluggish as I pulled it back in the garage. I started it up today to go for a quick ride and it was not pulling as much vacuum as it was yesterday and it felt a little sluggish but still, VERY fast compared to when the comp r lifters were still in the car. For comparison, it made about 12" vacuum on cold startup and about 13 or 14 after it was warm. In my pre comp r days 15 to 16" Hg at idle was about right for my cam.

I have a feeling that the valves need to be readjusted with the car running. I set them to 1/4 past 0 but it was a bit rough since the car was completely cold and the lifters were not pumped up (although they had been sitting in oil). To adjust them I did not do the EOIC method, I just saw an open valve and adjusted the other valve on the same cylinder to get the car running.

My questions are: could the initial startup after replacing the comp r's have ran so well because the lifters were not fully pumped yet, and once they were pumped, it revealed that they were too tight because of the loss of vacuum. What else could explain the deterioration of performance and vacuum as the car ran longer?

And lastly, and most importantly - HOW DO YOU FIND ZERO LASH WITH THE CAR RUNNING. I have searched for hours, and the only conclusion I came up with is that peope do things differently. I can't hear anything under the hood so please don't suggest listening for clacking... I can't imagine how anybody could do it that way. There has to be a definitive way to do this and set the valves right once and for all.

 

With it running ya just back them off till they clack,then tighten until they just don't clack and go the extra 1/8-1/4 turn and lock her down.

 

So you are saying that you can definitely hear the rocker clack and you can identify the EXACT moment the rocker stops clacking? Even with all that noise from the valvetrain and the exhaust??? Oh and don't forget about the damn whine from the blower right in my face on the driver's side. It's very hard to hear but I guess I'll try that method since a lot of people have had success with it. But there has to be another way to do it...

 

There is no other way, other than listening, to adjust them while running. I always adjust mine with the engine off and never had any problems.

 

Ya can hear it. The "exact moment" is not critical. Ya have over .100 thou in the lifter for adjustment.
Ya will hear it when it starts and stops.

 

So with the engine off I should use the exhaust opening intake closing method?? I have never tried that method before. I usually just set the valve that is closed without considering whether the other is opening or closing. Is it likely in that situation for the lifter to not be at the base lobe of the cam and screw up the adjustment?

If there is so much flexibility in the lifter then why is it so critical to get the adjustment right? A 1/2 turn of preload is only about .017 inches. And there is 5x that amount in flexibility? That seems a bit iffy to me but I'll try to see how well I can hear the zero lash point with the car running.

 

im getting ready to set my valve adjustment because i think my valves set too tight which explains my backfire and my car to running rich due to not enough vacuum so keep the advice comming

 

I like to adjust them with the car off. Sets it right everytime, pluss saves the mess.

 

When I adjust them with the engine running, I use a mechanic's stethoscope. I loosen the lockscrew then, with the stethoscope in contact with the rocker at the pivot, I loosen the polylock until it starts to clatter, tighten until the clatter goes away, etc, etc. The stethoscope really helps eliminate all the other extraneous noises in the area .

 

There are several engine off adjustment methods outlined on my Tech Page.
Except for the light preload desired for the Comp Rs, the range of preload is quite wide. The aim is to get them uniformly adjusted. The range of preload acts as a buffer over time and wear, so that you don't have to adjust them all the time.

 

I always do the engine running method...faster and easier IMHO. I was able to hear the clack when i was running open headers so it shouldn't be a problem for you.

 

I like this idea. I have a steth so it would work... I'll try this later today.

 

The reason for 1/2 turn, is not for adjustment sake, it is so if the lifters pump up from valve float or toss that the valve is not held open far enough to hit the piston and they will relieve quicker in the short distance.

 

I agree with shoebox in that it is most important to have all the adjustment consistent across all the valves. But that 1/2 turn is working against relieving the lifter... On the high end, too much preload and a lifter that pumps up correctly will hold the valve open.

I will post later on how the steth idea worked.