Hi all,
Decided to check the clearance in my valves today and am having some really confusing issues. ((Valve clearance as in the space between the rocker arms and the tip of the valves.))

For starters:

Everything in the valve train is new. Timing gears, cam, lifters, push rods, rocker arms, fulcrums, valve springs, valves, and head.

In my manual, it states the acceptable valve clearance is between 0.100 and 0.200. The preferred range is between 0.125 and 0.175.

So, I purchased myself a feeler gauge and bled my lifters down to empty. Then, went down the row and brought each cylinder to TDC and checked valve clearances.

About 6 of them were easily in the preferred range, usually around 0.150 or so. The rest of them were a lot lower, around 0.105 - 0.110. Still in the acceptable range, but just barely.

However, my frustration is coming with some of the cylinders having very varied readings. For example, cylinder 1, the first time I checked it, it read 0.125 on the exhaust and 0.165 on the intake. After going through them all, I went through them again. This time, it read 0.080 (E) and 0.095 (I)! Way out of tolerance.

After finishing them all again (many of them very close to what they read the first time), I decided to check cylinder one again. 0.140 (E) and 0.165 (I)



I'm confused. That's quite a discrepancy. All three times the piston was brought with great care to TDC (looking through the spark plug hole and barely wiggling the harmonic balancer with a breaker bar until the piston completely peaks).
What number do I go with? Why is it so varied? What am I doing wrong? Does it need a shorter push rod or not?


Thanks all.

 

That is strange. I don't think you need different length push rods if the other five cylinders are fine. The only thing I can think of is if the cylinder 1 lifter plungers are partially seizing. Or the entire lifter in the bore. I would first think it's the plunger though.

 

Well, I did some more reading on line and from what the walk through said, it needs to be on the compression stroke.

Redid all the valves again on the compression stroke and here are the clearances I came up with.

1: 0.125
2: 0.162
3: 0.160
4: 0.169
5: 0.154
6: 0.162
7: 0.164
8: 0.150
9: 0.154
10: 0.164
11: 0.172
12: 0.130


Not sure why the numbers would be different on the different strokes. But if those are the valid numbers, looks like everything's right where it should be.

 

How did you have any rocker/valve tip clearance at all if you did this test at intakeTDC. At intakeTDC for a cylinder both rocker arms should be rammed right up against the valve tips. Now I'm the one confused.

 

When the piston's at TDC, both valves are be fully closed.
It just needed to be TDC on the compression stroke instead of the exhaust stroke.

 

These numbers are all good. The goal is to keep the lifter piston in it mid range, so as stuff wears out as the engine gets older you still have some adjustment range left.

How did you bleed down the lifter to do this test??

Jim

 

It wasn't too hard. After removing the rocker arm, I put a towel over the top of the push rod (to protect it), and then hit it with a hammer until it bottomed the lifter out.


Actually, I removed all the lifters (kept them in order), and then I had two extra lifters on the shelf that weren't pumped up. Went through cylinder by cylinder and moved the lifters from bore to bore, put the push rods in, installed the rocker arms, and then measured. Once done, I removed everything, moved the lifters to the next cylinder, installed, measured, etc., etc. Kinda time consuming, but it worked well, since I didn't really have any other means of bleeding my current lifters down.

 

This is why it is best to install the lifter without pumping them up, so you can check these measurements. If you pump them up before you install them... you really just have solid lifters.
Jim

 

Yeah, I didn't think of measuring valve clearance since everything was brand new. I thought about it later when it wouldn't stop ticking, and I realized the head and block had both been rebuilt, which could result in it needing shorter pushrods.