Steam holes
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Instructor
Joined: Jun 2005
Posts: 156
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From: Liverpool NY
Steam holes
When drilling the steam holes in the head for a 350 to 400 conversion, is it possible to over drill and poke into the intake area?
Last edited by Fscott; Feb 15, 2010 at 08:02 PM. Reason: stated question vaguely
Le Mans Master
Joined: Sep 2001
Posts: 7,739
Likes: 630
From: Unreconstructed, South Carolina
Yes. If you're not sure where to go or how to get there, then anything's possible; you're as likely to wind up in purgatory than where you'd hoped.
Also depends on which head you're drilling; they vary.
Stock 400 heads have larger (~1/4") OE holes along exhaust side & smaller (~5/32") OE holes along intake side. Stock 400 heads' OE steam holes along Both sides are drilled at shallow angle from deck pointing toward exhaust side. They're Not drilled straight aka perpendicular to deck.
Study this:
http://www.gregsengine.com/convertin...ds-to-400.html
*everything on the internet's suspect; including the very words I just wrote.
Also depends on which head you're drilling; they vary.
Stock 400 heads have larger (~1/4") OE holes along exhaust side & smaller (~5/32") OE holes along intake side. Stock 400 heads' OE steam holes along Both sides are drilled at shallow angle from deck pointing toward exhaust side. They're Not drilled straight aka perpendicular to deck.
Study this:
http://www.gregsengine.com/convertin...ds-to-400.html
*everything on the internet's suspect; including the very words I just wrote.
Racer
Joined: Jan 2007
Posts: 427
Likes: 1
Fscott, I have been down this path once before. I used a hand held drill with masking tape attached to the drill a few measurements up on the drill bit to control the depth while I accessed the steam holes.
I was lucky and no damage but had the same worries. A pressure test will give you piece of mind so you do not need to go back to this and move on.
There is many magical combinations of 350 - 400 engines. We built a 406 and can't get enough of that torque when that old Acadian/Nova hits third gear.
Dano,
I was lucky and no damage but had the same worries. A pressure test will give you piece of mind so you do not need to go back to this and move on.
There is many magical combinations of 350 - 400 engines. We built a 406 and can't get enough of that torque when that old Acadian/Nova hits third gear.
Dano,
