| Head gaskets [message #214043] |
Thu, 11 July 2013 11:05  |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
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Anyone have a general guide, 455 specific on replacing the head gaskets? Points on this job would be nice also. Tom,MS II
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: [GMCnet] Head gaskets [message #214047 is a reply to message #214043] |
Thu, 11 July 2013 11:34  |
Jim Miller
Messages: 501
Registered: March 2008
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On Jul 11, 2013, at 12:05 PM, Thomas Phipps wrote:
> Anyone have a general guide, 455 specific on replacing the head gaskets? Points on this job would be nice also. Tom,MS II
Replaced mine last year during the recovery process from a cracked head. My original gaskets were embossed steel shim stock, around 0.013" thick and are no longer available. Gaskets currently on the market are around 0.039". Dick Paterson was very helpful via telephone and he suggested that I have my heads milled down to account for the thicker gasket. I did as he recommended and had no problems with intake manifold fit-up after reassembly. I used the Fel-Pro 1155 gasket ($82/ea from Amazon.com).
Since I had the heads off the engine I had the septum between the center two exhaust ports welded up with nickel (just in case I ever get headers) and then I milled the entire exhaust manifold mating surface. I also milled the exhaust manifolds and bolted them right to the head with no gasket.
If you have the front of the engine apart you might want to check the meet-up between the water pump's ports and the timing cover's coolant holes. On mine I found that the water pump casting blocked about 30% of the hole in the timing cover on the driver's side. That was a significant restrictor to flow - and coincidentally or not - was also the side with the cracked head. The crack was right between the valves on cyl #1 and showed up quite well with dye penetrant.
Hope that helps!
--Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Head gaskets [message #214074 is a reply to message #214047] |
Thu, 11 July 2013 18:02 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
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<<I found that the water pump casting blocked about 30% of the hole in the timing cover on the driver's side>>
Jim continue with that description please. What/how did you trim out that 30%
Thanks
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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| Re: [GMCnet] Head gaskets [message #214076 is a reply to message #214074] |
Thu, 11 July 2013 18:53 |
Jim Miller
Messages: 501
Registered: March 2008
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On Jul 11, 2013, at 7:02 PM, Don Adams wrote:
> <<I found that the water pump casting blocked about 30% of the hole in the timing cover on the driver's side>>
>
> Jim continue with that description please. What/how did you trim out that 30%
Hi Don,
See pictures at: http://www.jcmco.com/gallery/album28
The pictures are a mock-up as I forgot to take a picture of the real thing. The area in white is the part of the water pump's casting that was obstructing the passage through the hole in the timing cover. I had to grind it out with a carbide burr in a die grinder. I only discovered this alignment problem when I had reason to take the timing cover off the engine with the water pump still attached - otherwise I'd never have seen it.
I ground out as much of the water pump's casting as I could comfortably do without weakening that area structurally.
I do not know if the cause of the problem was the timing cover's hole being in slightly the wrong place or if the water pump casting was bad or if it was a combination of the two.
Let me know if you have other questions.
--Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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Jim Miller
1977 Eleganza II
1977 Royale
Hamilton, OH
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| Re: [GMCnet] Head gaskets [message #214085 is a reply to message #214076] |
Thu, 11 July 2013 20:47 |
Don A
Messages: 895
Registered: October 2008
Location: Dallas, TX
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Very interesting. Something else to watch for.
Thanks for going to so much trouble.
Don Adams Dallas, TX
'76 26' Glenbrook, '90 Sidekick
rebuilt by R Archer, powered by J Bounds, Koba
[IMG]http://www.gmcmhphotos.com/photos/data/6109/G2.jpg[/IMG]
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