Valve clearances

[Benson]

So an engine with an original B cam and standard Model A valves uses the same clearances as an A engine with a standard cam?

Both Model A and Model B valves had mushroom valve stems and according to the Big Green parts book were the same valves for BOTH engines.

There is a difference between a Model B cam which has NOT been reground and one that has been reground.

1. A Model B camshaft which has not been reground uses Model B lifters which are NOT the same as Model A lifters. Using wrong lifters will damage camshaft and lifters.

Intake clearance is .015 and Exhaust is 0.022.

Note for a number of years Model B lifters are no longer being sold as new.

2. A Model B camshaft which has been reground uses what ever lifters AND clearances were specified by the cam grinder.

So if you have to replace the camshaft it is best to replace lifters with adjustable ones.

Note: Most double nut lock lifters have heels with diameter less than 1.00

Self locking have 1.117 lifters.

Using 1.00 lifters on many camshafts today will cause damage to cam and lifters.

Adjustable lifters require non mushroom valves. CORRECTION: I was thinking one piece valve guides and Mushroom valves.

IF you have a new Stipe cam like IB330 or IB340 use the lifters and clearances specified by Stipe.

 

[Benson]

Several correction have been made to original post #21

 

[katy]

Starting to suspect the lifter bores in mine as well. Is there any way to check this without taking everything apart?

You might try cranking the engine 'till a valve is at it's highest point, compressing the valve spring to take tension off the lifter and then try wiggling the lifter to see if it feels like excessive play.
You probably need to pull the manifolds to try that.
May work may not.

 

[Benson]

About valve noise:

Many times in past folks used hand tools to grind ends of mushroom valves while adjusting clearances.

If mushroom valves were not ground correctly then valve clearance might change as valves rotate.

 

[alexiskai]

Adjustable lifters require non mushroom valves.

Are we sure this is true? When I checked the valves on my coupe's engine, which was rebuilt in '84, it had single lock tappets and mushroom valves.

Edit: Possibly I'm confused about what mushroom valve means.

 

[Patrick L.]

Are we sure this is true? When I checked the valves on my coupe's engine, which was rebuilt in '84, it had single lock tappets and mushroom valves.

Edit: Possibly I'm confused about what mushroom valve means.

Take a look at Brattons. Part numbers 9170 and 9180

 

[Benson]

You are correct. I was thinking one piece valve guides and Mushroom valves.

 

[daren007]

What is excessive “play”. There tolerances set by the manufacturer. In my case the guides were worn beyond an expensive repair. Should never went out the door this way. Be advised.

 

[fundytides]

What is excessive “play”. There tolerances set by the manufacturer. In my case the guides were worn beyond an expensive repair. Should never went out the door this way. Be advised.

You are right. In my case I have no one to blame but myself. Had the block and rods rebabbited by one shop and a few years later had the cylinders bored and pistons installed at a different shop. In my youth and ignorance, didn't pay any attention to the valve train components. What are the factory specs for lifter diameter, lifter bore diameter (and resulting clearance)so I can determine which or both require attention?