piston to valve cl. check

richie 2 · 03-19-2014, 11:04 AM

any difference in measurement between using a checking sping and using a race spring? stocker bbc engine.

Alan Roehrich · 03-19-2014, 11:20 AM

There sure is. I check mine with a race spring and a fixture that uses the rocker arm to open the valve with a 1/2" drive pull handle, using a dial indicator on the valve spring retainer. I check every 5 degrees of crankshaft rotation from
25 degrees BTDC to 25 degrees ABDC for intake opening and exhaust closing. You will find valve train deflection in a big block Chevy Stock Eliminator engine to be impressive, to say the least.

randy wilson · 03-19-2014, 11:49 AM

Alan is right. There is a huge difference between actual spring pressure, and using checking springs. We've seen as much as .050. But that being said, if you get a min. one way, don't assume that min. applies when using actual spring pressure. In other words my min. is .035 intake, .080 exhaust with checker springs. I wouldn't use those numbers on actual spring pressure. At those settings I have seen the shadow of the exhaust valve in the piston. Other guys may have a very different take on this.

Alan Roehrich · 03-19-2014, 01:52 PM

If it is a rectangle port big block Chevy Stock Eliminator engine that makes enough power to be competitive, I'd be real surprised if you could not see the "shadow" of the valves on the piston.

DIV3CR · 03-19-2014, 02:14 PM

Check the valve lift at retainer with both
springs and see the difference

richie 2 · 03-19-2014, 07:30 PM

thank you.....exhaust im getting .105'' w/checking spring & dial indicator, .155'' w/race spring and clay method. The .028'' valve lash has been set while testing both ways...

richie 2 · 03-20-2014, 07:38 AM

thanks everyone....we are going with what we have measured w/the race spring installed. its well safe. The answer to the question therefore is "using the intended valve spring to measure p2v clearance gives appx. +.050'' more than what the checking spring method shows". sp.

Aubrey N Bruneau · 03-20-2014, 09:24 AM

Quote:

Originally Posted by Alan Roehrich

You will find valve train deflection in a big block Chevy Stock Eliminator engine to be impressive, to say the least.

THAT's impressive

!

Robert Simpson · 03-21-2014, 01:11 PM

Guys I wanted to ask a question about checking P/V clearance with a HYD/Shubeck set up? Do you put in a solid lifter and a longer push rod to make up for the overall length? Or do you use the shubecks and check as usual and figure in the approx .015 lifter slack? I would like to hear what you guys do to check the P/V on a SBC stocker set up.

Thanks

DIV3CR · 03-22-2014, 02:55 PM

I use a solid lifter with the push rod I race with. You wouldn't
use a longer one it would be shorter and that .015 I
don't think would make a difference.

03-19-2014, 11:04 AM	#1
richie 2 Senior Member Join Date: Feb 2009 Posts: 971 Likes: 425 Liked 205 Times in 93 Posts	piston to valve cl. check any difference in measurement between using a checking sping and using a race spring? stocker bbc engine.

03-19-2014, 11:20 AM	#2
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,107 Likes: 1,564 Liked 1,796 Times in 409 Posts	Re: piston to valve cl. check There sure is. I check mine with a race spring and a fixture that uses the rocker arm to open the valve with a 1/2" drive pull handle, using a dial indicator on the valve spring retainer. I check every 5 degrees of crankshaft rotation from 25 degrees BTDC to 25 degrees ABDC for intake opening and exhaust closing. You will find valve train deflection in a big block Chevy Stock Eliminator engine to be impressive, to say the least. __________________ Alan Roehrich 212A G/S

03-19-2014, 11:49 AM	#3
randy wilson Senior Member Join Date: Jan 2007 Location: N/A Posts: 882 Likes: 0 Liked 22 Times in 22 Posts	Re: piston to valve cl. check Alan is right. There is a huge difference between actual spring pressure, and using checking springs. We've seen as much as .050. But that being said, if you get a min. one way, don't assume that min. applies when using actual spring pressure. In other words my min. is .035 intake, .080 exhaust with checker springs. I wouldn't use those numbers on actual spring pressure. At those settings I have seen the shadow of the exhaust valve in the piston. Other guys may have a very different take on this. __________________ don,t have one Last edited by randy wilson; 03-19-2014 at 11:51 AM.

03-19-2014, 01:52 PM	#4
Alan Roehrich Veteran Member Join Date: May 2006 Location: Murfreesboro TN Posts: 5,107 Likes: 1,564 Liked 1,796 Times in 409 Posts	Re: piston to valve cl. check If it is a rectangle port big block Chevy Stock Eliminator engine that makes enough power to be competitive, I'd be real surprised if you could not see the "shadow" of the valves on the piston. __________________ Alan Roehrich 212A G/S

03-19-2014, 02:14 PM	#5
DIV3CR Junior Member Join Date: Oct 2011 Location: WISCONSIN Posts: 50 Likes: 0 Liked 3 Times in 1 Post	Re: piston to valve cl. check Check the valve lift at retainer with both springs and see the difference

03-19-2014, 07:30 PM	#6
richie 2 Senior Member Join Date: Feb 2009 Posts: 971 Likes: 425 Liked 205 Times in 93 Posts	Re: piston to valve cl. check thank you.....exhaust im getting .105'' w/checking spring & dial indicator, .155'' w/race spring and clay method. The .028'' valve lash has been set while testing both ways... Last edited by richie 2; 03-19-2014 at 07:56 PM.

03-20-2014, 07:38 AM	#7
richie 2 Senior Member Join Date: Feb 2009 Posts: 971 Likes: 425 Liked 205 Times in 93 Posts	Re: piston to valve cl. check thanks everyone....we are going with what we have measured w/the race spring installed. its well safe. The answer to the question therefore is "using the intended valve spring to measure p2v clearance gives appx. +.050'' more than what the checking spring method shows". sp. Last edited by richie 2; 03-20-2014 at 07:41 AM.

03-21-2014, 01:11 PM	#9
Robert Simpson Senior Member Join Date: Aug 2004 Location: Jacksonville, Florida Posts: 808 Likes: 7 Liked 20 Times in 12 Posts	Re: piston to valve cl. check Guys I wanted to ask a question about checking P/V clearance with a HYD/Shubeck set up? Do you put in a solid lifter and a longer push rod to make up for the overall length? Or do you use the shubecks and check as usual and figure in the approx .015 lifter slack? I would like to hear what you guys do to check the P/V on a SBC stocker set up. Thanks

03-22-2014, 02:55 PM	#10
DIV3CR Junior Member Join Date: Oct 2011 Location: WISCONSIN Posts: 50 Likes: 0 Liked 3 Times in 1 Post	Re: piston to valve cl. check I use a solid lifter with the push rod I race with. You wouldn't use a longer one it would be shorter and that .015 I don't think would make a difference.