Someone asked today about adjusting the valve lash on an SBC. I have seen this question asked more than once here lately and rather than throw the same stuff in every thread I figured it would be easier to make one thread with my method. This method of adjusting the valve lash will work on any engine that fires in this order 18436572. So it will also work for engines like big MOPAR for instance. It takes 2 complete revolutions of the engine. You start by rolling your engine up on TDC. Remember you can be 180 out when using the timing marks. A lot of guys put a finger over the spark plug hole and roll it until it blows their finger off the hole. But if you already have the rocker cover off to adjust the valves it is just as easy to watch the valves. When the #1 intake closes it is time for that cylinder to fire. Set it on zero and you just hit TDC. Now mark your harmonic balancer or your pulley at 90 degree intervals. You dont have to use your timing pointer for a starting place just as long as you start with some sort of landmark that you can recognize. I use the timing pointer because it is easier. I rotate my engines by hand, if you are rotating your engine by hand it is important to remember that it rotates clockwise; if you roll it over backwards this will not work. <O</O Here is the order in which you adjust your valves. On TDC adjust: intake #2 and exhaust #8. <O Now roll it 90 degrees. Adjust intake #1 and exhaust #4 90 degrees Adjust intake #8 and exhaust #3 90 degrees Adjust intake #4 and exhaust #6 90 degrees Adjust intake #3 and exhaust #5 90 degrees Adjust intake #6 and exhaust #7 90 degrees Adjust intake #5 and exhaust #2 90 degrees Adjust intake # 7 and exhaust # 1 OK youre done. Believe me its a lot easier to do than it is to explain.
Great post Mr. Pork'n'Beaner!!!!My father and I can appreciate the importance of valve lash. He joined the U.S. Air Force 1952 and was stationed in Wyoming-trained as a diesel mechanic. He was sent to Alaska to serve on one of the D.E.W Installations-----Distant Early Warning Line----to repair and maintain diesel-generators in the Korean War! The Air Force DRILLED valve lash into his head and I received the same as I grew up with a mechanic for a father. I recall setting the valve lash on a Y-block the same Clearance as a solid cam small block chevy----TO SMART TO CHECK THE BOOK or ask the OLD MAN----fired it up up ---it was looppppin so ffffnnnn bad and the old man walked in and said" 19 GO --22 NO GO!!!!!!!!! Keep Up The Good Work!!! Thanks Dennis
There was a time that setting valve lash was part of tunning one. If your world is measured in .001 of a second it is a vital part. When I was real young on a Saturday morning at the garage I told the Ol' Man I could run the valves on a 427 he was getting ready for a race on Sunday. He wrote the sequence and the lash down for me. Then went and poured himself a cup of coffee and set down. We fired it when I was done he listened for a minute and said, "you got some valves tight son." Opened it up and he ran them again. Several were tight. The he said, "well you'll get it right someday." Important get to right, get 'em too tight they won't rev get 'em too loose the pushrods won't stay in the socket. I'm not sure I want to say why I know that.
Several cam grinders say to use this;Pick any cylinder, rotate the engine until the exhaust valve begins to open,adjust the intake lash.Continute to rotate the engine,same cylinder,when the intake valve opens and then cycles until just about closed,adjust the exhaust.
Thats the way i have done it since i was a teenager (an old timer showed me how).I take it a step further with hydraulics though as i warm the engine up and do one side at a time .When im done with one side i warm the engine back up and do the other side.I keep a rag there to dry my hand and roll the pushrod with my fingers to find zero lash then preload .It cracks me up to see guys trying to adjust valves on motors with it running.I usually go through them twice to double check then im happy ...
If you don't have a sequence that is about the only way to do it. I had an old fella tell me once that as long as the lifter was on the heal of the cam you were OK. basically as long as the valve was closed. I have done it that way in a pinch. I'm trying to work up a simple sequence for my 394 now. Its going to take more adjustments than a hydraulic chebby so I need to work it out so that it doesn't take me all day to do it. The old motor has an odd fireing order as compaired to the Chevy/MOPAR motors, 18736542. Once I knuckle down and do it it shouldn't take any more revolutions than the SBC. Or if someone just wants to enlighten me that would be sweet.
We do it this way at the track a lot, but you dont have to do the same cylinder at the same time. Watch the other cylinders on that side of the motor and look for exhaust opening, etc. I can do one side of the motor with four bumps of the starter. Depends on your firing order however. This is a double swap big block.
The best way I find to do this works from the idea that on any V8 engine there are always two cylinders at TDC at the same time. Given that circumstance it is also the case that when one of these cylinders is firing the other is going through the overlap phase. That is the exhaust is closing and the inlet is just opening.That's what we used to call "rocking". Quite plain to the eye to see this happening. What you do is identify the correct firing order and numbering of the cylinders. In the example of the SBC the f.o. is 18736542. What this means is that at the time that 18736542 are firing then respectively cylinders 65421873 are "rocking" on the overlap phase of the cycle. Once you have established that relationship then you simply start with no. 1. Turn the engine until no.1 is rocking and then adjust both valves on no.6 as both valves are closed for the firing stroke. Continue to run through the firing order to get each cylinder to arrive at the rocking point and then adjust the corresponding firing cylinder. This works for 4 cyl. and 6 cyl. engines as well provided it is known that you have two pistons moving in pairs both reaching TDC at the same time and 360 deg. apart on their cycles.
This is the only proper way to set your valves,The other methods may work ok with stock hyd cams, but anything aggressive and requires a lash adjustment no way. you need to be on the base circle of the cam for each valve,the quarter turn method will have you stopping on different parts of the ramps and your settings will be all over the place. And I dont hop around,start at number one cylinder and go right down each bank in order. This isnt a race to see who gets done first,The race comes after we are ready Tony
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