Kevin,
I usually tend to post the bad stuff on the chicago f-body list.
I guess I just got used to it that way.

The first time I adjusted the lifters, I did it by bringing each cylinder to TDC and went 1/2 turn past zero lash.

Yesterday, I loosened up all of them and proceeded to do the same only did 1/8 past zero lash this time. The rockers were terribly noisy (sounded louder than the exhaust ) and I was already late for my dyno appointment so I couldn't re-do it.

Jim said each cylinder to TDC isn't the right way to do it... hmm. I'm not sure which method he used, (if he's reading this, maybe he could tell us?) because I was waiting in the office, but the car ran and sounded EXACTLY the same way that it was running when I did it the first time. He said the rockers were so loose he was surprised they didn't fall off.

Brian,
I'll let you know when I come back, but the car will stay in storage till the snow is gone, so you could either listen to it in the garage or just wait until it's nice outside.
The converter locked at 85 MPH (stock), so the run was pretty much with the converter locked.

 

fwiw, I always make sure the lifter is on the base circle before lashing them. I rotate the crank quarter turn, look at which valves are near full lift and adjust the adjacent valve. At TDC the lifters are not on the base circle, unless of course you've got a cam that has zero overlap Repeat until all valves are lashed. Since the lifters compress after being loaded I only place a rocker arm onto its stud when I'm ready to adjust it, just so I don't get confused as to which ones are lashed or not.

Another thing people sometimes screw up is using the "rotate the pushrod" method of finding zero lash. Some people start to compress the lifters but can still rotate the pushrod with enough force. I jiggle 'em up and down while tightening the nuts by hand, it's obvious when zero lash is achieved. When you get a feel for it you can just tell by resistance in turning the nut.

 

Ion,

I will talk to Jim about setting the valve lash. We have always used the TDC method on my car, and its noisier than hell. I think we went like a 1/16-1/8 of a turn past zero lash and left it Its noisy and I need to do something. ALso, in the spring I will bring the TA up to school and will show you how my new Joe Overton cam drives. LAter

Brian

 

Yep, I think that's what INTMD8 was trying to tell me... I guess I'll try your method next time.


97bowtie,
I'll have some track numbers this spring. I've got ET Streets ready for her. I wonder if she's ready for them?

 

BOTH valves are off the seat at TDC. The exhaust valve is closing and the intake valve is opening. Cams have overlap where both valves are open around TDC. By lashing at TDC you are guaranteeing both lifters are off the base circle! I think most people would be surprised to see just how long each valve is open relative to piston position, especially on a large cam.

 

Yep, sounds like you did it exactly the way I did it the second time.... Mine were VERY noisy.
You heard the car when I did the rockers first time... it was real quiet even after I put the exhaust on.

I got these directions from a friend and shoebox's webpage. I guess I should've done a little more research.

 

Buttercup,
Could you email me in detail when you have time the way you set the valve lash?? I was also told to do the valve lash your way by comp cams, but my buddy of mine wanted to do them at TDC . Well anyway, I will be changing valve lash again this spring when I do a cam swap.

Brian

 

Sure thing, it's simple

 

my email is smknta95@hotmail.com

 

I'm in the process of it right now

Just to be clear you can adjust the valves at TDC of the compression stroke but you do have to make sure it's the compression stroke, not the exhaust stroke which is why I don't recommend it.

 

Actually, thats the way we did it. I pulled out the number one spark plug and manually turned the motor over until air shot out of the plug hole(compression stroke). At this point, we proceded to set the lash on number 1 intake and exhaust. I then manually turned the motor over 90 degrees and did the next in the firing order. ANd so on and so on until we did all 8. Would this work?? I still am interested in seeing your way.

Brian

 

hey brian, shoot that email over my way too if you can ima need to know that once my heads are done

ive never set the valves on a hydrolic lifter motor so i have no idea, and i obviously dont want noisy rockers

 

Depends, were the rockers on there tight enough to open the valves? I know it sounds stupid but I can picture someone with rockers so loose they wouldn't open the valves much if at all or no rockers at all installed. If the valves aren't opening then you'll get air shooting out of the hole whether it's the compression or exhaust stroke.

Because hydraulic lifters will naturally collapse with little pressure when the engine isn't running I remove them all and install/lash each one individually.

 

Cant believe i am just seeing this thread.

Great numbers Ion, i know you have been working on her for awhile. I would guess you are making right about the same HP as me (kinda hard to tell with different rear ends and trannies), but she should scream down the track.

Congrats again.

Jared

 

Your cam is going to overlap between the exhaust stroke and the intake stroke. IE as the cylinder comes to TDC on the exhaust stroke, your intake valve will be opening.

The cam is absolutely positively 100% on the base lobe at TDC before the spark. Your exaust valve isn't opening till a good 30-60 degrees after TDC on the power stroke. The intake valve closed long before TDC. If what you were saying is true you would show NO compression at TDC. When I adjust rockers via the TDC method, you want to make sure it is at TDC AND between the compression/power stroke. IE once you see the intake valve close, keep turning to TDC. That is where you lash the rocker.