Valve Adjustment

[USA1LT1]

I'm the proud owner of a 1971 Mulsanne Blue LT1 which I purchased about a month ago. The car has 64k miles and is all original with all matching numbers except for the Carb which seems to have replaced in 1973. I just recently joined the list and enjoy reading about our fine and special cars.

I would like to adjust my valves and would like to hear from other DIY'ers out there. The manuals that I have mention the valves are to be adjusted hot the while the engine is running. Will this make a mess or are there better and/or less messy ways to accomplish this. I typically do all the work on all my cars unless it involves to many hours under the car on my back then I would take it to a shop.

Any recommendations for a shop in the Orange County/Los Angeles area.

 

[tomtom72]

USA1LT1 kudos on your vette! I had one way back and I had a sent of GM manuals the orig. owner ordered with the car. I remember the manuals listed two methods. One was with motor runing, and one with the motor warmed up to all fluids at normal operating temps. The motor off method has a very specific sequence for the order of valves adjusted! The motor runing method had a 'tip' from the mechanics feed back. They said take a set of std metal SB valve covers & cut out the tops so you could work thru the top and keep the oil from runing out of the heads on to the block & exh. manifolds. This tip was hand written in my manuals and the orig. owner said he got it from a chevy dealership mech. that was his buddy. Now I had a 72 so I don't know how much translates to a 71, but motor all warmed up, idle sel. disconed,restart= idle speed of 450 rpms= just enough oil preassure not to squirt out side the cut covers. Only thing was swapping covers fast enough so the motor didn't get too cold. The book said just discon idle sel. to limit oil loss. Don't know if this helps. tt72

 

[Mike Baskette]

Welcome, I too purchased my 71' LT1 this year. I just took the car in as the valves were very noisey. After the adjustment and tune it was like night and day. I suspect it was because the valves were not closing correctly. Check my posts from three to four months ago and you will read my angst over this issue. There must be a good tuner in the O.C., ask around. Mike in San Diego.

 

[USA1LT1]

Thanks Mike. There are numerous shops around in OC but I would prefer to do this myself. I am still learning about the car. The car runs perfect as far as I can tell with the engine purring like a kitten and roaring like a lion when I step on it. I will check the back posts for your other list.
Frank

 

[F4Gary]

My engine guy says set them cold and your done. Don't worry about setting them hot. Unless your going racing, I guess the thermal expansion is negligeble. I think he said to set them just before the other valve in the respective cylinder opens. An old racer trick I think. I set mine cold and it runs great. No mess.

 

[69autoXr]

If your LT-1 is original, it has solid lifters and the lash must be set using a feeler gauge. I think you will find it very difficult to do this with the engine running. Hydraulic lifters can be adjusted with the motor running, but not solids. The engine should be hot, otherwise the clearance will be too tight when the lash is set cold. You can either follow the order in the book or use exhaust opening/intake closing, which is the easiest method I've used. All you have to remember is exhaust opening/intake closing. Pick a cylinder to start with, probably number one, but it doesn't matter. Turn the motor over until the exhaust valve begins opening, and continue until the exhaust valve is about half open. This places the intake lifter on it's base circle on the cam, and now the intake lash can be set. For the exhaust side, turn the motor over past the intake valve's fully open point, when it's about half closed, set the exhaust lash. The major benefit to this method is it allows you to adjust all the cylinders on one side without having to go back and forth from one side to the other.

 

[F4Gary]

Well said, 69, that's what I was trying to say but couldn't remember.

 

[USA1LT1]

69autoXr & F4Gary,
Thank you both very much. Sounds like good info. The car is very quiet (valve wise) and I will go with the engine hot not running method when the time comes for me to adjusts the valves. Keep up the good replys.
frank