Max Valve Stem Clearance - Team Camaro Tech
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post #1 of 6 (permalink) Old Dec 28th, 05, 02:43 PM Thread Starter
 
Join Date: Jul 2005
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Max Valve Stem Clearance

I'm in the process of changing out my valve springs to match the XE294 cam I've installed. While I was breaking down the head I noticed the intake valves have some play. So I set up my indicator and I'm getting about .010 movement when the valve is just off the seat. It looks like the guides were nurled at one time as I can see slight spiral marks down the hole. There is also pc seals on the intakes which I plan on replacing because it will puff smoke on start up. The heads are 840's BB. The car will never see the strip. Compression test during the summer was 175lbs. - 190lbs. cold. Does .010 sound to much or ok for occasional cuising?
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post #2 of 6 (permalink) Old Dec 28th, 05, 07:15 PM
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Bill
 
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Re: Max Valve Stem Clearance

Car,
That measurement really does not mean much. You need to measure the stem to guide clearance with a bore gauge to get a correct measurement. A lot of replacement guides have a spiral groove for improved lubrication, so the grooves might be ok too. I would have to check a valve in a head to see how much it actually moves, but I am betting yours is ok.

Bill Koustenis
Owner
Advanced Automotive Machine
Waldorf Md
1971 Chevelle "Heavy Chevy" original owner


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post #3 of 6 (permalink) Old Dec 28th, 05, 08:00 PM Thread Starter
 
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Re: Max Valve Stem Clearance

BillK, Thanks for the reply. When I go back to work after the holidays I'll bring home what we call "roll pin gauges" and then I'll recheck with them. What would be the max dimension?
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post #4 of 6 (permalink) Old Dec 28th, 05, 08:25 PM
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Steve
 
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Re: Max Valve Stem Clearance

0.010" is way excessive if that's what it really is.
Guides are usually machined to 0.001" - 0.002" stock, and wear limits as high as 0.0035". Possibly 0.0045 exhaust.
If your giudes were knurled, have new K-lines installed. Knurling guides is a cheap "Band-Aid" solution that won't last, -especially in anything with a half decent cam.
Good guide clearance is around 0.0015" +/- 0.0005".

Nov 68 Van Nuys. 327 floor-shift-auto, Frost Green and not much else when new.

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post #5 of 6 (permalink) Old Dec 29th, 05, 10:03 AM
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Re: Max Valve Stem Clearance

Quote:
Originally Posted by BlackoutSteve
... Knurling guides is a cheap "Band-Aid" solution that won't last, ...
I agree - particularly on the intake.

Dave
========================
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI
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post #6 of 6 (permalink) Old Dec 29th, 05, 10:16 AM Thread Starter
 
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Thumbs up Re: Max Valve Stem Clearance

I mic'd the valve stems and they are .372. I found a body of a drill bit that checks out at .373 and that went in the guide. I then took a piece of drill rod that mic'd .375 and that would not go in. So that means the guides are .374 which is .002 over the stem dia. From what you guys say the limit is .0035, I should be ok.
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