Valve adjustment attempted

Bruce Allert · 07-29-2002, 09:38 PM

I decided to check my valve adjustment after hearing a an intermittant clacking noise coming from the passenger side of the motor. I checked them using the TDC method. I found when set at TDC the feeler gauge wouldn't slip in between but, if I moved the wheel a little bit it would slide in with a slight drag. I did this with all the valves and found them to be in adjustment (I think). This leads to my question. Is the valve adjustment supposed to be exactly at TDC and once the tire is rotated the valve will open even more? Or was I just a hair off in my finding TDC? I really don't want to put the valve covers back on with the new gaskets until I get some sort of confirmation. If it isn't the valves making this noise what else could it be? The exhaust makes a duel tone sound ever so often and there feels like there's a wee bit of a power loss. Could it be from an injector or a plug fouling. I'm rambling so I'd better go to bed. Hope I have an answer soon! Thanks....... bruce

JWest · 07-30-2002, 04:06 AM

If you were looking at the correct cylinder, then the "closeness" to the TDC mark is not that critical, and should not change the adjustment. At this location you are on the base circle of the cam, and you have to rotate really far before you get to the ramp of the lobe and the clearance starts to change.

One of two things I can think of - either your cam has considerable wear and is just not round on the base circle anymore, or you adjusted on the wrong cylinder (1 instead of 3 for example). In this case the valves will be moving as you rotate the engine (exhaust closing, intake opening) but they wil both be nearly closed right at TDC. Your adjustment will end up loose, however.

3D914 · 3D914's Garage

Bruce,

I agree with James. My solution is to use the second method that is noted in the PP Tech Article on Valve Adjust. It doesn't rely on TDC, and I find it to be much easier for a one-person valve adjustment. If I remember right the author was Jim T.

It relies on the simple principle that each cam does double duty, so when, for example, #2 exhaust and #3 intake rockers are depressed (the cam is high and pusing on the rods), then #4 exhaust and #1 intake are closed and free to be adjusted.

Another thing I've learned the hard way is not to rely soley on the method of pulling the feeler gauge between the valve and rocker, as you should be able to push it thru as well and not have the gauge buckle.

Good luck,

rfoulds · rfoulds's Garage

Of course anothe rproblem might be that you have Hydraulic lifters. When I attempted a valve adjustment, I had the same symptom you described. That was when I called the PO and asked if the cam and valves were stock.
"oh yeah, I had them bus valves put in." was the response.

JWest · 07-30-2002, 08:07 AM

Randy - I thought about hydraulics, too, but I was afraid to start THAT whole topic!

rfoulds · rfoulds's Garage

Yeah, I know. from now on let's just say "the H word..."
or since we all like acronyms, HLWSHD (hydro lifters which spark heated debates)

Dave at Pelican Parts · Dave at Pelican Parts's Garage

...And the only way to be absolutely certain is to pull a lifter out, which requires removing the rocker stand, the pushrod, and the pushrod tube...

Is this the first valve adjust done on this car since you've owned it?

--DD

Bruce Allert · 07-30-2002, 02:23 PM

Thaks to all that responded to my valve adjustment dilima. In answer to Dave's question, The valves have been adjusted quite regularly but not by me. This is a first for me. So, before I put everything back together I will double check all the valves again. I can push and pull the feeler gauge without it buckling and there is still a slight drag to it. I'm am assuming the valves only open once each with the piston rotation. If that is so then all I have to do is rotate the drive wheel until it opens and check the adjustment. Is this right???

Howard H · 07-30-2002, 07:30 PM

Bruce:

Either your last posting was mis-stated, or you are operating under a misconception. In order to adjust a valve, it must be fully closed. That's because what you are really measuring with the feeler gauge is the gap that will be taken up when the cold push rod lengthens as it comes up to operating temperature.

Other than that, two suggestions ---

First, make sure that the engine is cold (at ambient temperature);

Second, use the method refered to in 3D914's posting.

Best of luck,
Howard

Bruce Allert · 07-30-2002, 08:47 PM

Howard... I have been known to operate under mis-conceptions but, in this case, it's probably dyslexia! Yes, I did mis-state what I meant as to the open/close of the valve operation. I realize my statement must have raised some eyebrows like (does this guy have enough bricks?) I hope y'all got a chuckle out of this... I did! Also, thank you Howard for pointing this out to me. Once I read your answer the light bulb came on and I heard Homer Simpson go "DOH"! Thanks to y'all & to all a good night......
bruce