Piston to valve clearance? - Team Camaro Tech
Engine General Engine Discussion.

LinkBack Thread Tools Display Modes
post #1 of 7 (permalink) Old Nov 15th, 02, 10:57 AM Thread Starter
Join Date: Oct 2002
Location: Hansville,Wa. USA
Posts: 11
With the heads mounted to the block how can I figure piston to valve clearance?
AFR 195 heads, (new cam, 506 lift), 10.1 c.r. domed pistons.
tdsk1967 is offline  
Sponsored Links
post #2 of 7 (permalink) Old Nov 15th, 02, 11:12 AM
HwyStarJoe's Avatar
Join Date: Jan 2001
Location: New Taxes York
Posts: 15,365
This is BY FAR not a technical explaination and is probably not complete:

Put a blob of modelling clay on top of one or more of the pistons, torque the heads to specs with the gaskets that you're going to use, rotate the engine until that piston or pistons has run through full intake and exhaust, pull the heads and see how deep the impressions are. You can then measure the clay at the depressions by either using a dial indicator or ruler and comparing the measurement from the deck surface to the piston surface compared to the deck surface to the deepest depression in the clay, and figuring out the difference.

I've never done it, but I've read a lot of stuff about checking the clearances and this is only one method.
Correct me if I missed anything....

[This message has been edited by HwyStarJoe (edited 11-15-2002).]
HwyStarJoe is offline  
post #3 of 7 (permalink) Old Nov 15th, 02, 11:22 AM
Senior Tech
Join Date: Feb 2002
Location: Williamstown,PA
Posts: 500
Check your email.

'69 RS Camaro
355 5-speed 4.11
1 2RUN is offline  
post #4 of 7 (permalink) Old Nov 15th, 02, 04:42 PM
Senior Tech
Join Date: Apr 2001
Location: Vacaville, CA
Posts: 10,474
One other thing, if you are running a hyd. cam you will need a solid lifter to check. A hyd. lifter will not give you a true reading. I took a hyd. lifter apart and made it into a solid by removing the internals and stacking washers in the body. once that was done I put the push rod cup/seat back in and replaced the snap ring. Of course you could just use a dial indacator and push the valve down the proper amount and then measure the clay.

camaroman7d is offline  
post #5 of 7 (permalink) Old Nov 16th, 02, 02:30 PM
Senior Tech
Join Date: Dec 2000
Location: Kentwood, MI
Posts: 8,097
Whatever you do, DO NOT use a head gasket when you do the modeling clay method. If you do you just wasted a perfectly good head gasket for no reason. Just put everything together WITHOUT a head gasket and measure the thickness of the compressed clay on top of the piston. Then just add the compressed thickness of the head gasket (from the packaging) and you have your number.
Eric68 is offline  
post #6 of 7 (permalink) Old Nov 16th, 02, 11:13 PM
Senior Tech
Join Date: Feb 2002
Location: N.W. Washington
Posts: 7,963
the clay trick does work well, but IMO, the best way to do it is with a light spring, installed in place of your valve spring and a dial indicator on the retainer. this gives you real accurate readings of v to p which is really important if they are going to be close. the clay is good for a rough estimate, it's been done that way for years, but if you want to know for sure and are running close, use a light spring and a dial indicator. also, as eric said, leave the gasket out and just figure that in to the equation, using its compressed thickness. good luck! edit; after re-reading your post, i'd be very surprised, even amazed, if you don't have a ton of clearance w/ that cam, so clay will probably do, but then again, it's good to learn how to do it the most accurate way.

[This message has been edited by 68rs406 (edited 11-17-2002).]
68rs406 is offline  
post #7 of 7 (permalink) Old Nov 18th, 02, 02:21 AM
Senior Tech
Join Date: Nov 2000
Location: denton md
Posts: 239
I prefer the clay method. It gives you a picture of what is realy going on and were. The valve spring method works great but it only gives you a reading at the closest point. They clay shows how close you are to walls and plugs.
roger69 is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome