Cylinder head question,again.

terry1 · 09-07-2009, 06:42 AM

In stock eliminator,if your intake/exhaust runner volume(s)is to large,according to spec,do you have any recourse to reduce the volume?Or does the head go to the scrap heap?
Second;is there a tolerance in the volume numbers,0.1%,1.0%.no %

Terry Cain · 09-07-2009, 06:44 AM

Scrap, door stop.
No tolerance if over

Alan Roehrich · 09-07-2009, 06:50 AM

Depending on the valve you have in it, it may be possible to reduce the volume slightly by changing valves, although it will likely hurt performance. It might require a custom valve.

Terry Cain · 09-07-2009, 06:54 AM

Also, it's possible to cut intake or exhaust side of head or intake to make it a little smaller. NOT much room to work with here though.

Jody Lang · 09-07-2009, 11:06 AM

I should start a new thread for this, but I'll start here. There's a problem in the specs for the Stockers. I personally know of 4 people that have checked their runners and all 4 have been big on the exhaust. These are various Chev motors. In 3 of these it's only been 1 of the heads that's been big.

These are not acid heads either. The specs were for the Super Stock heads. Those that could braze/epoxy in the ports to get the desired CC's.

The new rule is affecting innocent racers that just assume their ports are ok because they're stock.

Jeff Lee · 09-07-2009, 02:46 PM

You can reduce the runner volumes by cutting the intake or exhaust surfaces as mentioned. Rule says you can not go past the valve cover bolt hoe.
You can also reduce those volumes by sinking the valve(s) deeper in the pocket. With some valve jobs you can gain flow by doing this correctly. Key word is correctly.
If it was a particularly rare head I would look at all avenues. If it's your dime-a-dozen head I'd scrape it.
And no, there is no tolerance on the plus side.

09-07-2009, 04:45 PM

I agree with what Jeff Lee is saying. I have fixed this problem a few times before. You can sink the valve/seat, which in most cases can reduce 3cc's or more depending on the valve diameter. And in most cases will increase the flow and air speed thru the port. Call or email me if you need help with this.
Best Regards,
Chris Hardy
231-773-7252
chrishardy@racingenginetechnologies.com

09-07-2009, 06:42 AM	#1
terry1 Member Join Date: Sep 2006 Location: Moncton, N.B. Posts: 276 Likes: 24 Liked 24 Times in 13 Posts	Cylinder head question,again. In stock eliminator,if your intake/exhaust runner volume(s)is to large,according to spec,do you have any recourse to reduce the volume?Or does the head go to the scrap heap? Second;is there a tolerance in the volume numbers,0.1%,1.0%.no %

09-07-2009, 06:44 AM	#2
Terry Cain Senior Member Join Date: Feb 2008 Location: Georgetown, Indiana (close to Louisville, KY) Posts: 760 Likes: 492 Liked 224 Times in 103 Posts	Re: Cylinder head question,again. Scrap, door stop. No tolerance if over __________________ Terry Cain ???? STK tcain@twc.com

09-07-2009, 06:50 AM	#3
Alan Roehrich VIP Member Join Date: May 2006 Location: Murfreesboro TN Posts: 4,916 Likes: 997 Liked 1,046 Times in 276 Posts	Re: Cylinder head question,again. Depending on the valve you have in it, it may be possible to reduce the volume slightly by changing valves, although it will likely hurt performance. It might require a custom valve. __________________ Alan Roehrich 212A G/S

09-07-2009, 06:54 AM	#4
Terry Cain Senior Member Join Date: Feb 2008 Location: Georgetown, Indiana (close to Louisville, KY) Posts: 760 Likes: 492 Liked 224 Times in 103 Posts	Re: Cylinder head question,again. Also, it's possible to cut intake or exhaust side of head or intake to make it a little smaller. NOT much room to work with here though. __________________ Terry Cain ???? STK tcain@twc.com

09-07-2009, 11:06 AM	#5
Jody Lang Member Join Date: Mar 2002 Posts: 299 Likes: 28 Liked 81 Times in 25 Posts	Re: Cylinder head question,again. I should start a new thread for this, but I'll start here. There's a problem in the specs for the Stockers. I personally know of 4 people that have checked their runners and all 4 have been big on the exhaust. These are various Chev motors. In 3 of these it's only been 1 of the heads that's been big. These are not acid heads either. The specs were for the Super Stock heads. Those that could braze/epoxy in the ports to get the desired CC's. The new rule is affecting innocent racers that just assume their ports are ok because they're stock.

09-07-2009, 02:46 PM	#6
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 2 Times in 2 Posts	Re: Cylinder head question,again. You can reduce the runner volumes by cutting the intake or exhaust surfaces as mentioned. Rule says you can not go past the valve cover bolt hoe. You can also reduce those volumes by sinking the valve(s) deeper in the pocket. With some valve jobs you can gain flow by doing this correctly. Key word is correctly. If it was a particularly rare head I would look at all avenues. If it's your dime-a-dozen head I'd scrape it. And no, there is no tolerance on the plus side. __________________ Jeff Lee 7494 D/S '70 AMX

09-07-2009, 04:45 PM	#7
Chris Hardy Guest Posts: n/a	Re: Cylinder head question,again. I agree with what Jeff Lee is saying. I have fixed this problem a few times before. You can sink the valve/seat, which in most cases can reduce 3cc's or more depending on the valve diameter. And in most cases will increase the flow and air speed thru the port. Call or email me if you need help with this. Best Regards, Chris Hardy 231-773-7252 chrishardy@racingenginetechnologies.com