I have a C2 Corvette with a 327 engine. This engine has hydraulic lifters. I had to have new valves seals installed, which, of course required removing the heads. I have the heads re-installed, the valves adjusted on a preliminary basis, and the car runs well. The only problem is that I have a slight valve "clatter" when the engine is hot. Yesterday, I got all of my ducks in a row and attempted to do a final hot valve adjustment. It was an abject failure Between my age, my arthritis, and the hot engine, I found it impossible to do so. I was able to do the initial adjustment cold with little problem but adding a hot engine pushed the task over the edge for me. Before I go out and actually pay someone to do this for me, I thought I'd ask the SBC experts here if there is any way to adjust the valves cold and get them close enough to eliminate the "clatter". I know the usual way is to get the lifters to sero lash and then tighten them a half turn to get the lifter into it's operating range when hot. Is there an alternative way to do this cold that will work? Perhaps, a quarter turn from zero or three quarters turn? Anybody out there have any other tricks? I'd really rather do it myself.
Lots of info and ways to do it, but this one might be the best one for you. I use 1/2 turn after taking just feeling the resistance trying to spin the pushrod. 1. Valves can be set on a hot or cold engine. A cold engine is a lot more comfortable to work on. Major camshaft manufacturers recommend setting valves cold, to avoid erroneous adjustments on lifters that may be "pumped up" If you are setting valves on a fresh engine that has not been run, everything should be well lubricated before you begin. 2. Remove both valve covers and remove the spark plugs to make the engine easier to turn over. Also, If you are setting valves on all cylinders, it is generally easier and less confusing to just loosen all of the rocker arm adjustment nuts before you begin. This also allows for all of the internal lifter plungers to return to their "home" position. 3. Using a long handled ratchet or breaker bar attached to the crank bolt, turn the engine over in the clockwise direction. A. Starting with #1 cylinder, turn the engine over until the exhaust pushrod just begins to move up. B. At this point, stop and adjust the intake valve on the same cylinder. 1) Tighten the rocker until you can roll the pushrod between your thumb and forefinger with the slightest bit of resistance. 2) At this point tighten between an additional quarter to half of a turn. C. You have now adjusted the #1 intake valve. You will now want to turn the engine over while watching the same intake pushrod that you just set, it will go full open and then begin to close. When it is almost closed, stop and adjust the exhaust rocker arm on that particular cylinder. By following this procedure, you are assured that both of the lifters are at the base circle of the cam and that there is no additional pre-load applied to them from cam lift at this point. D. You are now able to repeat this procedure on the remaining cylinders. 4) Re-install your valve covers and your valve adjustment procedure is finished
Trying to work in a hot c-2 engine compartment is cramped , uncomfortable & in no way fun .Set them cold . Things that really help , a remote starter switch to bump the engine over , memorizing EOIC , ( say it with me) , finally , Poly locks , you can turn them by hand & feel exactly where 0 lash is , then use tools to turn that 1/2 turn & lock it, don't have to wiggle / spin / fuck with pushrods , plus , they don't damage the studs .!!
Thanks for the information. I am still a little confused; some say 1/2 turn, while others say 3/4 to 1 turn. I thought 1/2 turn was for a hot engine, and the goal here is to get them set properly cold. I would like to have a set of "poly-locks", but everything else is new, and I'd like to do this today or tomorrow. It looks like I can do this cold (Hallelujah!) if I am careful and use the right technique. I'm just not sure what it is yet. Maybe a few more posts will help. C'mon guys! With the fan and belts in the way, turning the engine over is a pain. This is an L79 cam; will the following technique work (as it requires the engine to only be turned twice). Get #1 to Top Dead Center Exh.- 1 3 4 8 Int.- 1 2 5 7 Get #6 to Top Dead Center Exh.- 2 5 6 7 Int.- 3 4 6 8
Since the Ramps on an L-79 aren't overly long , that should work fine , 1/2 or 3/4 or 1 turn is more about what you prefer more than having any significant operational difference...
1/2 turn will work. 1 turn will work. If you adjusted them properly when cold, then the lash is set right, and the noise is due to some other issue. The difference between hot and cold is a very small fraction of half a turn.
Success! Finished running the valves this morning and just returned from a 10 miles drive, parked it and opened the hood. No more "sewing machine" noises. I go them to zero lash and gave 'em another 3/4 turn. Determining zero lash is a learned skill, but once you know how to do it, it's easy. One thing I did "cheat" on is that I glued a 5/8" 6-point socket to the crank pulley bolt with a couple of dabs of JB Weld so I could easily turn the engine. The socket slipped off the bolt every time I turned it, and had I not done that, I'd still be up there, setting the first set of valves. I'm generally a flathead guy with an occasional foray into setting the adjustable pushrods in the hemi in my race car, but I don't have much experience with these engines. Thanks for everyone's help, and especially to those who said it doesn't need to be done hot; they were right!
Tubman, I'm glad you got it worked out. I've always used the #1, #6 tdc method, and turned down 3/4 turn. Always worked in my applications.
Yup. Look at what a 1/2 turn is on a 24 pitch thread. A full turn is .04166", half is close enough to a linear .022". A healthy hydraulic lifter has enough cushion built into it for some adjustment leeway.
The Jalopy Journal
