87 vette 81 big girl

You will do OK setting your Vettes engine valves.

The technique I listed works on any 4 cycle internal combustion engine with a single in block camshaft or Overhead cam engines with adjustable valvetrains.

But it will not work on a V-504 diesel engine.
I found that out myself 2 years ago after overhauling the engine in the Chassis.
Had to get out the service manual.
That diesel engine is a beast all its own to work on and repair.
Road grader.

I concised my instructions to you.
I could have written 4 pages on the topic but you would have fallen asleep along with others after page 1.

Brian

MyFirst90coupe

fired it up last night, set base timing to 6 degrees BTDC.

Still a damn rattle in the top end. I went back over the drivers side because it's the most easily accessed. Drove it to work today just to see what would shake out. Once it gets really nice and warmed up it sounds foul.

While I was double/triple checking the preload on drivers side last night I looked at the valves to double check the contact patch from the rockers and there are no markings to indicate that there are any unwanted contact areas. They are all in the center of the top of the valve on that side. I was tired / burned and blistered last night so I didn't double check the other side. That will be for another night of fun.

engle1147

Sorry to hear about all the extra noise.
I hear you when you mentioning you check the "contact patch"/witness marks but did you ever check for the correct pushrod length with the 1.6's mounted up?

Your video below. To me the "slap" does sounds like valvetrain issue - incorrect preload and/or pushrod length is off in the video.

MyFirst90coupe

Maybe I'm confused then. I thought the reason you measured pushrods was to make sure that your rockers contacted the center of the valve stem.

Midnight 85

If the contact patch is centered then the pushrods have to be the correct length. Mine was off a bit and it took a .3 shorter pushrod to bring it to center position. Did you try my suggestion of moving the p-rod up & down until you feel zero movement? Also you can add another 1/2 to 1 full turn after zero and still be okay, I prefer 1/2 turn.

C4Betts

Something else to look at. If you put a straight edge over the polylocks you can see a pattern of where each of the locks are in relation to all the valves. They may all be about the same height (no gap under the straight edge for every poly lock) or a pattern (every intake is the same height and every exhaust is the same height). You would do this after setting all the valve lash.

This will tell you if you've got an extreme or 'unique' rocker/valve/pushrod/lifter situation going on. Something that is out of range compared to all the others.

By and large, every polylock should be the same height. Or at least every intake should be the same height and every exhaust should be the same height. If they are not, you've got valve stems that are different lengths, valve seats that are letting the valve move further up into the head (burned? damaged?), a cam with base circles that are smaller/larger in diameter (really hope that isn't the case), etc.

MyFirst90coupe

I followed Brians instructions and yours to make sure that I was at zero. Then I added 1/2 turn.

It is a stock engine/ stock cam / heads were cleaned up and new seals installed / 3 way valve job & valves ground / Felpro 1010 head gaskets / comp guide plates / 7.2 hardened p-rods / comp 1.6 ultra gold RR's / new GM lifters installed.

It really should not be that hard and I'm not an idiot. Atleast I don't think I am but it sounds like someone is under the hood with a spray paint can shaking it on decel and initial acceleration.

Will I be safe going 1 full turn after Zero?

engle1147

at mid lift only the tip should be centered on the stem. The reason I mention this is because you can + or - preload all day long but if you have the wrong length pushrods you'll still get some extra noise. If your sure the pushrod length is correct then no worries.

1/4 to 1 full turn of preload after "0" should not be an issue.

MyFirst90coupe

I will look at the position of the rocker tips tonight. All of the ones I looked at last night showed a nice centered contact mark on the top of the valve stem.

Midnight 85

engle1147, you & I are saying basically the same thing, if the pushrod is correct the overall "footprint" left on the valve stem will be centered. You are correct that it should be dead center at mid lift but I wasn't going to suggest he look for mid lift, just the over all picture. My First 90, did you color the valve tip with a black marker then set the rocker & rotate the engine a couple turns to get the contact area?
Lastly, how does the car run even if it is noisy? My 1.6 rr drove me nuts trying to quiet them down until I found out it was impossible to do.

engle1147

The "footprint" comment is right on and i agree some noise may stay but to me the OP's noise/slap seems loud enough it might even trigger false KS counts.

Seems like various preloads levels have been attempted with less than positive results to me it seems like it is time to look else where for the cause.

Even if all the head work was done by a reputable shop - after the valves/seats/stems were ground, heads were resurfaced and/or cleaned up valve stem tip height may have changed quite a bit....a minimum of a pushrod measurement is in order at this point.

MyFirst90coupe

Ok, I set them at +3/4 turn last night using the method described by Brian. Still a noise.
I did notice that one or two of the valve stems show that the rocker is riding on the outer half.

Sort of like..




The local speed shop has pushrod checkers that he will loan out. I might stop by at lunch and pick up a set. I'm not 100% sure how to do that but I'm sure I can find it either on the forum or the WWW somewhere.


It is more pronounced at idle and cruising at low speed and seems to be generating from the drivers side.

My friend that was helping me out last night seems to think it's not an engine noise now but maybe an exhaust leak. I'm not so sure. I have double and triple checked the header flange bolts and I am going to check the collector bolts tonight just to make sure.

engle1147

That's pretty normal for those heads with non self aligning rockers - adjustable pushrod guide plates would help center things up.

Midnight 85

I would imagine there are a few different ways to check pushrod length just as there is to set rockers. Here's how I did mine, I adjusted the p-rod to the same length as the stock ones. I then colored the tip of the valve stem with black marker. Set the rocker, then turn the engine over a couple revolutions then pull the rocker back off & see where the "footprint is on the tip, if it is not centered, shorten the p-rod .010 and do it all again. If the footprint then shows you are going the right direction, (shorter) then take another .010 off the length and try it again. Keep doing this until you get the footprint centered. If anyone sees anything wrong with my explanation speak up or if you have an easier, quicker way let's hear it.

hooked073

pull valve covers. Fire it up. if it is infact valve adjustment related you can deaden the sound by putting pressure on the rocker while it is running. While the VC are off engine running do each rocker one at a time this way. Lossen rocker till you here it tapping then tighten it stops tapping go an additional 3/4 turn and you are done go to the next one do the same thing. Sometime I will go over all of them a 2nd time. This is 100% positive way. you dont have to worry about lobe position ect. Do I normaly do it this way no. But it is a lot eaiser to grasp then all the other ways.

MyFirst90coupe

Caught a cold that my son brought home with him so I haven't done a thing to the car. I might get to it this weekend. I'm tired of hunching over the damned thing to be honest.


Need that winning lottery ticket!