Tips on filling Exhaust Crossover

[Glenn Briglio]

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]

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]

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]

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]

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]

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]

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.