Tips on filling Exhaust Crossover - Page 2

Mike Taylor 3601 · 12-16-2015, 10:34 AM

I started using zinc years ago when a customer brought in some he had bought from Mondello,I buy mine half price of what Mondello got for it,have never had any of the zinc disappear ,burn out or erode or whatever you want to call it. I may switch to aluminum, because I always have barrel full of old pistons.
Do you just use plain old cast piston ?
Mike Taylor 3601

Glenn Briglio · 12-16-2015, 01:24 PM

Quote:

Originally Posted by Mike Taylor 3601

I started using zinc years ago when a customer brought in some he had bought from Mondello,I buy mine half price of what Mondello got for it,have never had any of the zinc disappear ,burn out or erode or whatever you want to call it. I may switch to aluminum, because I always have barrel full of old pistons.
Do you just use plain old cast piston ?
Mike Taylor 3601

Use forged pistons. Some cast pistons have a steel insert in pin area.

Tom Goldman · 12-16-2015, 01:42 PM

I've poured dozens of AMC heads over the years.
I melt old cast pistons in a cast iron fry pan over my turkey fryer burner .
the pan is small enough to handle the amount of aluminum you will need.
You must skim the dross off the top of the aluminum before pouring.
As far as prepping the head , the crossover port must be free of carbon to ensure proper filling.
I use furnace cement to block the port side for the fill, making sure its in the hole a little ,per the rules.
You can get a small tub of the cement at any hardware store ,and its relatively
easy to remove when your done .
It also helps to warm the head before the pour. ....I usually get them up to 225 deg. before I pour....This helps prevent shrinkage due to the rapid heat transfer to the head.

B/S 428 · 12-16-2015, 02:09 PM

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

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, 10:34 AM	#11
Mike Taylor 3601 VIP Member Join Date: Oct 2008 Location: Somerset,Ky Posts: 1,362 Likes: 337 Liked 279 Times in 96 Posts	Re: Tips on filling Exhaust Crossover I started using zinc years ago when a customer brought in some he had bought from Mondello,I buy mine half price of what Mondello got for it,have never had any of the zinc disappear ,burn out or erode or whatever you want to call it. I may switch to aluminum, because I always have barrel full of old pistons. Do you just use plain old cast piston ? Mike Taylor 3601

12-16-2015, 01:42 PM	#13
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,473 Likes: 881 Liked 858 Times in 234 Posts	Re: Tips on filling Exhaust Crossover I've poured dozens of AMC heads over the years. I melt old cast pistons in a cast iron fry pan over my turkey fryer burner . the pan is small enough to handle the amount of aluminum you will need. You must skim the dross off the top of the aluminum before pouring. As far as prepping the head , the crossover port must be free of carbon to ensure proper filling. I use furnace cement to block the port side for the fill, making sure its in the hole a little ,per the rules. You can get a small tub of the cement at any hardware store ,and its relatively easy to remove when your done . It also helps to warm the head before the pour. ....I usually get them up to 225 deg. before I pour....This helps prevent shrinkage due to the rapid heat transfer to the head. __________________ Tom Goldman 1500 SG , 1506 STK

12-16-2015, 02:09 PM	#14
B/S 428 Junior Member Join Date: Jan 2011 Posts: 87 Likes: 18 Liked 154 Times in 34 Posts	Re: Tips on filling Exhaust Crossover Is this legal in stock? the way I read it, you can fill the intake manifold port but not the head. Brian 627 stk

12-16-2015, 10:05 PM	#17
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,473 Likes: 881 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	#19
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 !