Intake Manifold Rule

GTOMayhem · 08-12-2016, 09:24 AM

Rule book states:

INTAKE MANIFOLD
Must retain the unaltered stock manifold, consistent with year and
engine horsepower claimed. Grinding, sandblasting, or any other
modification to manifold prohibited. Any film coating inside
manifold prohibited. Runners and plenum must retain OEM
appearance. Final acceptance at the discretion of the NHRA
Technical Services Department.

I know it is common practice with Pontiac intakes to separate the coolant crossover from the intake, to allow a better intake to port alignment. Is this practice used in Stock Eliminator?

Also, is the modification restriction only apply to the actual intake ports? Or can one modify cooling passages?

Rick Thomason
GTOMayhem

ss3011 · 08-12-2016, 09:34 AM

INTAKE MANIFOLD
Must retain the unaltered stock manifold, consistent with year and
engine horsepower claimed.

This says it all . I would not try to pass tech with the coolant crossover cut off the manifold .

GTOMayhem · 08-12-2016, 11:15 AM

What about blocking the small exhaust holes under the front of a quadrajet on the 67 only Pontiac intake?

ss3011 · 08-12-2016, 11:43 AM

You can do that by getting a different carb gasket . So there won't be any modification to the manifold . Those passages probably don't do much if you filled the exhaust crossover ports in the cylinder head , which is a legal modification .

Dwight Southerland · 08-12-2016, 12:13 PM

Work to align the intake ports; the water passage will take care of itself. People have been racing Pontiacs in Stock Eliminator for over 50 years and I do not think any slight misalignment of water passages in the intake manifold has ever been an issue.

R. Thorne · 08-12-2016, 03:15 PM

Fill the exhaust crossover in the heads. Do away with the water pump o ring to manifold (grind it down and put a pipe plug in). This will allow you to shift the intake back and forth to align the ports. Ron.

GTOMayhem · 08-12-2016, 05:33 PM

Quote:

Originally Posted by R. Thorne

Fill the exhaust crossover in the heads. Do away with the water pump o ring to manifold (grind it down and put a pipe plug in). This will allow you to shift the intake back and forth to align the ports. Ron.

So, you block it off with a pipe plug in the timing cover and another in the manifold? If so, then in general(not Pontiac V-8 specific) you could use a pipe plug to plug any hole, such as a coolant passage, in any intake manifold?

Rick Thomason
GTOMayhem

08-12-2016, 09:24 AM	#1
GTOMayhem Member Join Date: Oct 2014 Posts: 172 Likes: 673 Liked 22 Times in 14 Posts	Intake Manifold Rule Rule book states: INTAKE MANIFOLD Must retain the unaltered stock manifold, consistent with year and engine horsepower claimed. Grinding, sandblasting, or any other modification to manifold prohibited. Any film coating inside manifold prohibited. Runners and plenum must retain OEM appearance. Final acceptance at the discretion of the NHRA Technical Services Department. I know it is common practice with Pontiac intakes to separate the coolant crossover from the intake, to allow a better intake to port alignment. Is this practice used in Stock Eliminator? Also, is the modification restriction only apply to the actual intake ports? Or can one modify cooling passages? Rick Thomason GTOMayhem

08-12-2016, 09:34 AM	#2
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Intake Manifold Rule INTAKE MANIFOLD Must retain the unaltered stock manifold, consistent with year and engine horsepower claimed. This says it all . I would not try to pass tech with the coolant crossover cut off the manifold .

08-12-2016, 11:15 AM	#3
GTOMayhem Member Join Date: Oct 2014 Posts: 172 Likes: 673 Liked 22 Times in 14 Posts	Re: Intake Manifold Rule What about blocking the small exhaust holes under the front of a quadrajet on the 67 only Pontiac intake? Attached Thumbnails

08-12-2016, 11:43 AM	#4
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 909 Likes: 70 Liked 239 Times in 114 Posts	Re: Intake Manifold Rule You can do that by getting a different carb gasket . So there won't be any modification to the manifold . Those passages probably don't do much if you filled the exhaust crossover ports in the cylinder head , which is a legal modification .

08-12-2016, 12:13 PM	#5
Dwight Southerland VIP Member Join Date: Dec 2001 Location: Arkansas - In the middle of everything. Posts: 1,999 Likes: 64 Liked 772 Times in 192 Posts	Re: Intake Manifold Rule Work to align the intake ports; the water passage will take care of itself. People have been racing Pontiacs in Stock Eliminator for over 50 years and I do not think any slight misalignment of water passages in the intake manifold has ever been an issue. __________________

08-12-2016, 03:15 PM	#6
R. Thorne Member Join Date: May 2009 Posts: 182 Likes: 61 Liked 100 Times in 33 Posts	Re: Intake Manifold Rule Fill the exhaust crossover in the heads. Do away with the water pump o ring to manifold (grind it down and put a pipe plug in). This will allow you to shift the intake back and forth to align the ports. Ron.