| How to change cylinder heads on a 455 engine [message #90653] |
Thu, 01 July 2010 09:54  |
Michael Bozardt
Messages: 367
Registered: January 2007
Location: College Station, Texas
Karma:
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Senior Member |
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Having three "bad" valves, I have decided to change cylinder heads. One shop wanted $2000 to do it-if you can believe that.
Needing knee replacement surgery and battling the heat/humidity of Houston, I decided to have a go at it anyway. I was fortunate to move things around to get the GMC inside my shop out of the sun and it is so much better inside.
First, I got the engine up to top dead center(TDC). Then, I drained the radiator and oil.
So far I have unbolted the air conditioning compressor and laid it aside without disconnecting the freon lines. I also removed the upper A/C bracket that attaches to the intake manifold and the right cylinder head. I removed the alternator and alternator brackets. One bolt of the alt. front bracket is behind the power steering unit. To get the front bracket off, I removed a few nuts from the power steering fluid container. Then I was able to move it forward toward the front of the coach without removing it or disconnecting the fluid lines.
I have removed the L and R upper shroud brackets which are bolted to the fan shroud, intake manifold and the front of the cylinder heads.
I disconnected the upper radiator hose from the thermostat housing. I also removed the vacuum line to the distributor and disconnected the wire from the dist. to the coil. After checking that the rotor is pointed correctly, to the number 1 spark plug wire, I removed the distributor.
There is one more A/C bracket to be removed before I can remove the intake manifold with the carburetor. Earlier this year, I changed the carb and added an aluminum intake manifold so I have been there and done that.
Remaining to be done:
remove the valve covers
remove the rocker arms-keeping them in order to replace them where they originlly are.
remove the push rods, again, keeping them in order.
remove the cylinder head bolts and remove the heads.
I will replace these heads with two "J" heads that I sold to a "customer" in California. He returned them saying his machinist told him they were no good. As they had obviously been rebuilt before I acquired them, I figured he was, as a minimum, mistaken. So I kept the heads and now, in my time of need, I had them checked by a machine shop that builds race engines. You guessed it, the heads are good. Explanation! He found some cheaper heads elsewhere. But, as usual, God knew I would need these heads, so he had them returned to me. You know, if we look, we will see these minor miracles happening all the time.
I also will replace the plug wires and dist. cap with some Springfield Ignition stuff from Dick Paterson; also, the intake manifold gaskets, cylinder head gaskets and valve cover gaskets.
Will post later as the experience goes.....Michael at GEMRECS
There are three GMC parts coaches available at $500 each.
They have a number of usable parts like engine, trans, final drive, drive axles, CV joints, front and rear hubs, front knuckles, 1 dash, steering columns, some windows, 1 entry door, bunk/sofas, 1 late style driver's seat. Also good for body parts.
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