heads, gaskets, and bolts
As a new member I have enjoyed reading many older posts, incredibly informative, about 308 engines, rebuilding, and head options. There is a consensus(?) among the "older" enthusiasts
that the aluminum head is best used as an "object-d'art". Sealing and warping issues made for too many failures. If the "Best gasket" is used with modern head bolts and surfaces are absolutely flat, the C/R maintained at 7.5, and the engine is driven normally, will an aluminum head work ok? If the head bolt size was increased to 1/2 inch would that help as well?

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Comments
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dougson wrote:As a new member I have enjoyed reading many older posts, incredibly informative, about 308 engines, rebuilding, and head options. There is a consensus (?) among the "older" enthusiasts
that the aluminum head is best used as an "object-d'art.†Sealing and warping issues made for too many failures. If the "Best gasket" is used with modern head bolts and surfaces are absolutely flat, the C/R maintained at 7.5, and the engine is driven normally, will an aluminum head work ok? If the head bolt size was increased to 1/2 inch would that help as well?
The principle objection to the aluminum head usually does not resonate with the posters. The real reason the aluminum head has a bad reputation is corrosion which causes the head to leak coolant internally and externally and to blow head gaskets. The spacing of the cylinders in the Hudson 6s is minimal and that area must contain not only the combustion pressures it must also maintain the sealing necessary for proper cooling. Cooling additives and antifreeze during the time these cars were new did not meet the performance and corrosion standards needed to keep the head sealed. So, as time passed the Hudson Company issued maintenance bulletins which recommended the aluminum head is changed to the steel head. Again the real reason was the dissimilar metal corrosion which occurred with the aid of the less than adequate cooling fluids. Does this make the aluminum head Ok to use with the coolants available today? Well the jury will probably be out on that forever as few folks drive their Hudsons as full time vehicles and the body of evidence would be extremely small. For me... the first 308 I rebuilt was a 54 with aluminum head. It was frozen solid due to corrosion from the head.I cleaned it up and found another aluminum head and it ran AN OK... but, again I did not have the car for a long time and when it left my care it was running strong with the new aluminum head.
For long time reliability the steel head is a better bet... as dissimilar metal corrosion is still a fact of life.
Good Luck.0 -
I am running a 51 aluminum head on my fully built 308 (now 318) The block was decked and the head was resurfaced and calculated compression came out to 7.65. Not as much as I wanted but with the 7X reliefs I cut in the block, it is the best I can do without getting the head too thin. One would have to go with a 262 head or a Clifford head to get more compression. I am running the Best gasket with new grade 8 bolts and thick grade 8 washers. So far so good. I like the aluminum as it is 25lbs lighter than the iron and dissapates heat better. Looks cool to0
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I am using an aluminum head with 7/16" studs and a Best Perm-Bond Gasket with no prob.
I think all modern anti freeze has became far better today because of the numerous aluminum engines in use.
Go with an aluminum head using new bolts & hardened washers but make certain the head is true. Also re-torque head couple of times COLD before driving high speed.0
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