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| | | | Joined: Jul 2012 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2012 Posts: 59 | Hey guys I need to replace a cylinder head for my 57-62 235. whats the difference between a 3836850 gm 5 and a 3836848 gm4 cylinder heads? | | | | | Joined: Jun 2008 Posts: 1,388 Shop Shark | | Shop Shark Joined: Jun 2008 Posts: 1,388 | The difference is 2.
Hahahahahaha!
The 848 head should be higher compression, about 8 to 1 I think. Other than that, I think they are samsies. If I'm wrong, somone will come along and say so. | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | It looks like the 3836850 head is a 261 head, and the 3836848 is a 56-63 235 head.
The "848" head produces higher compression. The 261 head has extra coolant circulation holes in it. You could use it but I'd use a 261 head gasket with it (to seal off the extra holes).
| | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | You could use it but I'd use a 261 head gasket with it (to seal off the extra holes). I'm sure Tim means 235 gasket.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Do you think a 235 gasket, Dave? I go with your knowledge.
I was thinking that the metal rings at the coolant holes in the 261 gasket would make a positive seal from head to block?
| | | | | Joined: Jun 2008 Posts: 1,388 Shop Shark | | Shop Shark Joined: Jun 2008 Posts: 1,388 | See, look how smart they are! | | | | | Joined: Jan 2001 Posts: 5,337 'Bolter | | 'Bolter Joined: Jan 2001 Posts: 5,337 | I see what you are saying Tim. I think either would work fine. One may want to put a little sealer around those holes.
A 261 gasket has a much larger sealing ring around the combustion area due to the larger bore. Used on a 235 gives a dead area and some loss of compression. The dead area may not make much difference on these old engines but on emission engines it would cause increased emissions as unburned fuel would be caught in that area.
See the USA in your vintage Chevrolet! My Blog | | | | | Joined: Feb 2004 Posts: 29,747 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,747 | I'd use the 235 gasket. Without corresponding holes in the block, the steam holes won't have anything to line up with. No harm, no foul. The 848 head would be a better choice, if you've got both numbers to choose from.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Sep 2001 Posts: 29,269 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,269 | Thanks for the reasoning, Dave
I fully agree with you, Jerry - the 848 head being a better choice (If berts53 has a choice).
I'll eventually put an 848 head on my 261. I'll drill the coolant holes in that head and use the 261 gasket.
| | | | | Joined: Feb 2004 Posts: 29,747 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,747 | Tim, when you drill that 848 head, be sure to angle the holes slightly. The coolant passages in the head the holes are supposed to line up with aren't exactly in line with a hole drilled perpendicular to the head gasket surface. The holes are angled away from the combustion chamber a little.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Jul 2012 Posts: 59 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2012 Posts: 59 | Thanks for the info guys. They looked exactly the same. Unfortunately there is a crack in the number 4 cylinder in the same place on the 848 head. I gotta keep looking I guess. | | |
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