• If you log in, the ads disappear in the forum and gallery. If you need help logging in or getting registered, send request to: webmaster@southernairboat.com

Valve Adjustments

R

Robby Bondurant

Well-known member
I was just wanting everyone's input on how they adjust their valves.

I was told by my machinist to tighten them down till there is no play in the rockers, and then do a 1/4 turn more.

I have also been told to tighten them down till you can't move the pushrods any more, and then do a 1/4 turn more.

I just wanted to know what everyone else thought?

Thanks, Robby.
 
If say a small Block Chevrolet. tighten until taping stopped then 1/8 turn on hydraulic lifter.
 
It's a 98 Vortec 5.7 small block. It has the Votec heads on it but I put the edelbrock conversion to carb. It also has the hydraulic lifters and roller cam. Hope all this helps.
 
He is probably talking about adjusting with it running which works fine just can be a little messy. I always either crank it and pump up the lifters or if it is a new engine then I use a drill and a prime tool to pump them up the follow the directions as to which one to adjust when while turning the motor over by hand with a wrench. I never can remeber how it goes so i have to resort to readin the book each time fortunately I don't do it often enough to remember it.
 
Yeah, my old flat tappet motors are easy. Start at TDC on #1 and then just rotate it 90deg. each time and follow the firing order.

I'm afrid to advise since Robby's got a roller motor.

olf
 
well if its a new motor always prime motor before turning it over.
also if new read your spec for which valves to adjust at top dead the book will give you a sequence and a method but always adjust after it running. Then adjust after break in.
 
An old chevy distributor works good for priming the engine. Grind the teeth off the gear and I took all the advance stuff off so I had a small shaft. Then use an electric drill CW. A distributor housing or special tool is required in order to get oil everywhere. Socket on an extension doesn't do the whole job. After ZERO lash point is acheived it's a matter of preference as to how much you crank them down. Less chance perhaps of lifters pumping up with 1/4 turn past zero lash however I have seen people turn them down to 1 1/2 turns. 1/2 and 3/4 is pretty common. 8)
 
Rich, the GM rollers are still hydraulic and must be adjusted when the engine is assembled.

COLD is on the money.

I find it is best to adjust them without the intake on so I can grab the pushrod and shake it up and down while SLOWLY tightening the nut. You will be able to tell when the lash is zero: the push rod will stop moving up and down. Then simply turn it another 1/2 to 3/4 of a turn, which ever makes you feel better.

Then after you break the engine in, you can use Ted's method with the engine running to double-check and to take up any wear that occured during break-in of the cam

If it is too loose, the rocker will "tap tap tap tap". This stops when you get close to the right setting.

If you go too far, the engine will start to bog, or if you have a vacuum gauge hooked up, you'll see the vacuum drop.

And yes, it is very messy. They make clips to cover the oil hole in stamped rockers, but these won't work on most roller rockers and it is still very messy. If you have perimeter-bolt valve covers, you can cut the top out of an old one and install it to help keep the oil from going over the edge of the head onto the exhaust where it will make smoke.
 
Robby, this would be a good time to consider a set of roller rocker arms too. They adjust just like the others (1/2 to 3/4 turn after the slack
is taken out of the pushrod) and they're good for about another 20 horses.

Clockwise, Cold ..... it's a Chevy. :)

olf
 
I have never adjusted valve lash with the engine running. Most all hydraulic lifters are designed to run with a .050 pre load on the lifter plunger. Most all hydraulic lifters need to be brought to zero lash then if you have a 3/8 fine thread stud after removing all lash turn an additional 3/4 of a turn. This will give you the desired lifter preload on a hydraulic lifter.
 
Setting your lash running is a good way to get a bad BUZZ :? and maby start your boat on fire, keep an extinguisher handy. :lol: I was taught that method over twenty years ago and have not used it since the first time I tried a better way. BF, OOP'S That would be clockwise! :lol: FORDS on the brain, they are a ratio of about 100 Fords/1 Chevy at work. :shock:
 
You must log in or register to reply here.
Back
Top