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Rocker Arm Clearances too Large Symptoms


Jedi Warrior
I'm adjusting the rocker arms tonight, and I am finding the clearances on several of the valves to be around .020+. I am backing them down to .012.

I am curious, what does having the clearances to large mean to how my engine was running? I know this means my valves weren't fully opening, and I think that means I was being sapped of power. I had a lot of chatter, and I assume that was partially due to this.

What else does it cause? What should change as far as how the engine runs once I fix this?

I'm getting stuff done and having a Good Healey Day!

John Loftus

Darth Vader
Re: Rocker Arm Clearances to Large Symptoms


What else does it cause? What should change as far as how the engine runs once I fix this?

[/ QUOTE ]

Well, your gas milage might go down /ubbthreads/images/graemlins/lol.gif
Seriously though, I doubt that you will feel much difference. The valve chatter will be quieter but I'm guessing the change in power by adjusting those few valves will be small at average rpm. You might notice a difference at getting to higher rpms and smoothness as you get up there but most of it will probably be placibo effect /ubbthreads/images/graemlins/smile.gif But every little thing you can do to get the engine dialed in will help ... button it back up and let us know how it feels!

Dave Russell

Yoda - R.I.P
Re: Rocker Arm Clearances to Large Symptoms

I agree with John.

Differing clearances also will change the timing on those particular valves. It "might" idle a little smoother.


Senior Member
Re: Rocker Arm Clearances to Large Symptoms

Remember the law of diminishing returns....some improvement may be noted with tighter clearances, as well as less tappet chatter as you get close to specs, but if they sound TOO smooth, be careful of overdoing it... too tight and you run GREAT (until the valves start burning) /ubbthreads/images/graemlins/cryin.gif I found out the hard way when I thought "if a little bit is good, then a lot more should be better"
Country flag
Re: Rocker Arm Clearances to Large Symptoms

Depends on the cam too. My Isky requires .018" intake and .020" exhaust clearances. You'd have to dial in the cam timing to know if you have an aftermarket or original grind (degree wheel, dial indicator, etc.).

To agree with RVMAN, I've often said "loose valves won't cost you money...

... tight ones will!"
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