Tips on filling Exhaust Crossover

Mark Yacavone · 12-16-2015, 04:16 PM

Quote:

Originally Posted by B/S 428

Is this legal in stock? the way I read it, you can fill the intake manifold port but not the head. Brian 627 stk

I can't quote the rulebook, but yes, as long as you don't use the fill to re-shape the port.
It's been done for decades.

B/S 428 · 12-16-2015, 04:45 PM

Quote:

Originally Posted by Mark Yacavone

I can't quote the rulebook, but yes, as long as you don't use the fill to re-shape the port.
It's been done for decades.

Okay Mark thanks. I find the rulebook a little confusing sometimes. Brian 627stk

Tom Goldman · 12-16-2015, 10:05 PM

The cyl head section in the rule book reads ,"heat riser passage may be blocked from the intake manifold of the cylinder head .
Blocking the passage down in the valve pocket prohibited"
As long as the filler is recessed from the pocket ,it's legal.
You wont find a spec anywhere ,but I've seen Record holding heads that the filler is recessed about 3/8 of an inch.

dartman · 12-17-2015, 09:31 AM

Quote:

Originally Posted by Tom Goldman

The cyl head section in the rule book reads ,"heat riser passage may be blocked from the intake manifold of the cylinder head .
Blocking the passage down in the valve pocket prohibited"
As long as the filler is recessed from the pocket ,it's legal.
You wont find a spec anywhere ,but I've seen Record holding heads that the filler is recessed about 3/8 of an inch.

does anybody have that in " notified of approval in writing from NHRA" on how far recessed it must be ? as stated in the section "how to use this RULEBOOK" on page XVII of the 2016 NHRA rulebook

just asking as my head guy will not fill them.

ss3011 · 12-17-2015, 10:53 AM

I poured these heads with aluminum yesterday. Interestingly the cast Pontiac pistons I used did not have any metal struts in them. First piece of advice is practice on a head you don't care about first, and the second is make the pour in one shot, trying to add extra aluminum after a short fill may risk having the extra material you pour after, get loose and fall out. I am worried about warping or damaging the head by using a torch to melt the aluminum back out of the passage. Also to prevent aluminum from flowing down the exhaust guide , so I fixed a valve stem into the guide backwards so the tip was flush with the port down in the bowl. That worked out well . I also fabbed up a V -trough to help guide the aluminum past the valve seat. That also worked well. As I said before , Thanks for all the tips. Like anything, the more practice you get the better you get at it !

12-16-2015, 10:05 PM	#3
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,473 Likes: 882 Liked 858 Times in 234 Posts	Re: Tips on filling Exhaust Crossover The cyl head section in the rule book reads ,"heat riser passage may be blocked from the intake manifold of the cylinder head . Blocking the passage down in the valve pocket prohibited" As long as the filler is recessed from the pocket ,it's legal. You wont find a spec anywhere ,but I've seen Record holding heads that the filler is recessed about 3/8 of an inch. __________________ Tom Goldman 1500 SG , 1506 STK

12-17-2015, 10:53 AM	#5
ss3011 Senior Member Join Date: Feb 2002 Location: Southeast Michigan Posts: 908 Likes: 70 Liked 238 Times in 113 Posts	Re: Tips on filling Exhaust Crossover I poured these heads with aluminum yesterday. Interestingly the cast Pontiac pistons I used did not have any metal struts in them. First piece of advice is practice on a head you don't care about first, and the second is make the pour in one shot, trying to add extra aluminum after a short fill may risk having the extra material you pour after, get loose and fall out. I am worried about warping or damaging the head by using a torch to melt the aluminum back out of the passage. Also to prevent aluminum from flowing down the exhaust guide , so I fixed a valve stem into the guide backwards so the tip was flush with the port down in the bowl. That worked out well . I also fabbed up a V -trough to help guide the aluminum past the valve seat. That also worked well. As I said before , Thanks for all the tips. Like anything, the more practice you get the better you get at it !