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[GMCnet] Steam Holes...??? [message #333182]

Thu, 07 June 2018 15:45

Kingsley Coach

Messages: 2691
Registered: March 2009
Location: Nova Scotia Canada

Karma: -34

Senior Member

I know I'm missing something...
https://www.classiccarrestorationclub.com/article/building-a-400-for-400-horses/#utm_source=newsletter&utm_campaign=A6202&vsoid=A6202

Mike in NS

--
Michael Beaton
1977 Kingsley 26-11
1977 Eleganza II 26-3
Antigonish, NS

Life is too short to hold a grudge; slash some tires and call it even !
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Re: [GMCnet] Steam Holes...??? [message #333212 is a reply to message #333182]

Thu, 07 June 2018 19:53

roy1

Messages: 2126
Registered: July 2004
Location: Minden nevada

Karma: 6

Senior Member

Chevy added those to the small block 400 when they first came out in the early 70's. When I built my 400 Chevy I used a 350 set of heads and drilled the steam holes probably had something to do with the fact the 400 has siameze cylinders.

Roy Keen Minden,NV 76 X Glenbrook

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Re: [GMCnet] Steam Holes...??? [message #333225 is a reply to message #333212]

Fri, 08 June 2018 09:23

Matt Colie

Messages: 8547
Registered: March 2007
Location: S.E. Michigan

Karma: 7

Senior Member

roy1 wrote on Thu, 07 June 2018 20:53

Chevy added those to the small block 400 when they first came out in the early 70's. When I built my 400 Chevy I used a 350 set of heads and drilled the steam holes probably had something to do with the fact the 400 has siameze cylinders.

Those are common to lots of siameze cylinder engines. They have to have mates in the head gasket to work and bore distortion leading to high lube oil consumption and blow-by is also common.

Matt

Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit

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Re: [GMCnet] Steam Holes...??? [message #333227 is a reply to message #333182]

Fri, 08 June 2018 09:53

JohnL455

Messages: 4447
Registered: October 2006
Location: Woodstock, IL

Karma: 12

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The 400 SBC was just a confusing head scratcher. Way lighter than a 403 BB Chevy but a 400 BigBlock Buick was only like 25#heavier with plenty of meat in the block. Kind of makes sense they combined divisions into GM Powertrain.

John Lebetski
Woodstock, IL
77 Eleganza II

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Re: [GMCnet] Steam Holes...??? [message #333229 is a reply to message #333227]

Fri, 08 June 2018 10:30

James Hupy

Messages: 6806
Registered: May 2010

Karma: -62

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The 403 Olds has siamese cylinders and similar architecture to the 400
Chev. It also has a high nickel content block casting that resists the out
of round cylinders the Chev was famous for. I see lots of 403's in
motorhome use with well over 125 thousand miles on them. That speaks well
for them.
I have heard comments about swapping cylinder heads on 400 Chevy for
hi pro ones, only to have the bottom end fail. Easier to find a 4 bolt main
350 than to mess with the 400.
That's what I did with a K5 full sized Blazer. Originally a Diesel,
then swapped for a 400 small block, finally built a fairly good 350 4 volt
for it that lasted 15 years or so before the tin worms attacked the non
rust proof Fisher body. Those blazers and suburbans were wretched examples
of poor quality control and no rust proofing.
Jim Hupy
Salem, Or
78 GMC ROYALE 403

On Fri, Jun 8, 2018, 8:04 AM John R. Lebetski
wrote:

> The 400 SBC was just a confusing head scratcher. Way lighter than a 403 BB
> Chevy but a 400 BigBlock Buick was only like 25#heavier with plenty of meat
> in the block. Kind of makes sense they combined divisions into GM
> Powertrain.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
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Re: [GMCnet] Steam Holes...??? [message #333239 is a reply to message #333182]

Fri, 08 June 2018 15:29

kingd

Messages: 592
Registered: June 2004

Karma: 2

Senior Member

The heavy duty version of the mid 70s Chrysler 440 had steam holes in the top of the block
and the head. I've been told the blocks are not interchangeable with the non heavy duty version
and can't be made to be interchangeable. Also some ?? all?? 440 CID heavy duty cylinder heads
supposedly use taper seat spark plugs. Supposed to be for better heat transfer from the plug
to the head. My Dodge chassis 1976 26 foot Motorhome has a heavy duty 440. GMC related,
it came from the factory with the 12 V(24V) all electric refridgerator GMC MHs came with.

DAVE KING lurker, wannabe Toronto, Ontario, Canada

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