Alrighty guys.
So I bought an old 1986 vette with 120,000 miles.
I just did a recent adjustment for minor valve ticking and I had used the Hanes Manual Spec
0 lash + one full turn

Now I'm stuck with his horrendous loud clank when running. When I try cranking without starting there is no noise. I backed off the adjustment in quarter increments but to no avail.
Help!

What should I do?

 

Did you do this adjustment with the engine running (idling) for each valve (16 total)? You may also have one or more bad lifters.
SAM

 

Unfortunately it sounds like you may have a rounded cam lobe...upon cranking, did all the rockers show full movement? (as far as you could tell?) Also you may have collapsed a lifter. Just to be blatently honest, i think you should start thinking about your new camshaft. if you need the car up and running right away, you may as well start from ground zero and reset all the rockers, starting from #1 @ tdc and follow the I/E sequence. haynes has never been too informative as far as i am concerned. Get (or borrow) yourself a Chevrolet service manual (need not be for corvette) that covers the adjustment procedure with the motor off. It has NEVER failed me once. It tells you how to adjust, and bolt the covers on. No further adjustment needed. set it and forget it. Works really well! ( I will NEVER adjust with the engine running for as long as i live) if this doesn't work out, i'd go for a new cam and lifter set. Good luck

 

Ugh.
I didn't even think of that.

And no, I didn't adjust it with the engine running.

 

Do you think with what the Haynes reccomended that I bent the valve?

 

First you need to determine where the noise is coming from. Have you checked the flexplate to see if there are any missing teeth?

 

If you followed the instructions properly, i doubt it. I just mean that thier procedures are usually pretty Vague and hard to comprehend, not nessessarily incorrect

 

Well following the now tossed haynes manual I loosened the adjusting nut then tightened until all lash was gone from the lifter to pushrod to rocker then another full turn. Thats when the noise started and I began to back it off in quarter turn increments to no avail. Before adjustment the pushrods had quite a bit of slack but after I couldent even rotate them. Does that indicate it was too tight?

 

I would have to say without a doubt. The Valves MUST be at rest when this adjustment is being made. (you didn't mention if they were). If any rockers were actuating while you made the adjustment (eg. Valves not fully seated closed) they are beyond doubt incorrectly adjusted. (Engine not running while adjusted)

 

I made sure without a doubt that the valves were on the base circle when being adjusted. But even if the valves were adjusted the way i had them at first (zero lash plus one full turn) that i could have possibly bent a valve. If my cam or lifters gave the ghost I can deal im just not looking foward to a head rebuild as of yet. Probaly gonna replace the cam and lifters to be safe. Any ideas on a good power package?

 

Without reading the thread I hope your pistons are fly cut ,other wise you have a lot of bent valves.
No engine can take a full turn on the valves.
I only know of one and Comp Cams say's it is theirs.

http://corvetteactioncenter.com/foru...ad.php?t=45701

 

what sound would the engine be making while running (at idle) to indicate bent valves versus bad lifters/rounded cam?

 

I had that problem with a highter mileage motor. Start over. Back off the rockers until they are really loose. Give it a few minutes in case a lifter is sticking a little and tighten the rocker arm while moving the push rod up and down. When you can't move it up and down, tighten 1/2 turn. After you tighten that 1/2 turn it may bleed down and feel loose again. Don't worry about it leave it alone. Rotate the crankshaft. Repeat for the other valves. Might be a bad lifter. If so I would replace the cam and lifters.

 

[SNIP=sillyokio]Alrighty guys.
So I bought an old 1986 vette with 120,000 miles.
I just did a recent adjustment for minor valve ticking and I had used the Hanes Manual Spec
0 lash + one full turn [/SNIP]

SEE, this is exactly what I mean. How many times have I posted about the problems that occur when the manual's procedure is used for setting lifter preload? Anyone keeping count?

This is a perfect example of why I have always said don't use the overly complicated procedure you find in the shop manuals. Sure, it'll work, but ONLY if you really know what you're doing.

Even as recently as yesterday I sent a long private email on this very topic to a Forum member having the same preload setting problem using the manual's procedure.

I'd rather see someone resort to setting them with the engine idling than to use the shop manual procedure. The manual's procedure is JUST TOO PRONE TO RESULT IN AN ERROR. It's intended for someone who really knows his/her way around an engine, not a novice/beginner.

There a few different procedures posted on the Tech Tips section on this Forum. Any of them, other than the Shop Manual way, is better; but you must follow the directions to get any of them right.

If you have a problem locating them, email me - jakejr266@sbcglobal.net - and I'll send you a doc file I prepared on the procedure I use and recommend.

Hope this helps.

Jake

 

YES, and AS I'm the member that Jake sent the email to; there is ANOTHER bonus by using the method Jake describes; if you have a non stock cam (or don't know the history of the engine), the GM / Haynes method doesn't take this into account, as the lobes on a non stock will not be correctly adjusted by the factory method. ALSO; GM / Haynes method involves rotating the crank 1/4 turn, adjust lash, then 1/4 turn again and so on; just HOW do you EXACTLY FIND the 1/4 turn of the crank???

Yes, you can 'guesstimate' it by measuring string and dividing it, or by visually quadrantly using the position of the distributor rotor, BUT since there IS NO 1/4 or 1/2 turn marks on the crank pulley; this is SO open to error!

My advice for the fellow who started this thread, is echoed above several times; START OVER. If you were able to rotate engine by hand a full 360' without any feeling of tight spots (other than when cylinders offer resistance from compression stroke), then you may be ok regards to any bent valves...DON'T panic...Loosen all valves first perhaps before adjusting them, just to make sure you're not crunching them against any of the pistons As for one comment on the cam lobes going flat - that is utterly ridiculous - they're not inflatable!

 

To answer your ?,jPoping through the intake and throttle body bent intake valve one or more.
Poping through the exaust,bent exaust valve one or more.
If engine runs,make a mess and remove the valve covers and readjust valves ,turn nut counter clockwise until clatter and 1/4 turn back.
Don't go more then 1/4 turn, the valvelifters have to pump up .
You have already squeezed out the oil in them now we need to pump them back up.
Cam flat on you engine not to likely.
Those engines are hard to kill.

 

Jelloshot,
if you don't mind me asking, why won't you use the running method?

(I use it with no probs, no oil mess, I'm just curious)

 

Well, mine took one earlier today, so now you know of two.

 

.

I know I'm not him, but why WOULD you use the running method? I mean starter buttons are cheap, and useful for a lot more stuff then just this. Hell you could even use your wife/GF/brother-in-law instead... Fast, easy, no oil, no moving parts to cram your fingers into, just precisely set valves in the peace, quiet and in as much or as little time as you want - that is hard to argue against

 

Dunno HOW THAT could be at all accurate...
Only thing I ever adjusted whilst RUNNING was the cam chain rear tensioner of my old Honda CB750 motorbike...