Aluminum Heads - 8's

[Deleted User] · February 2006

Probably these questions will afford some of you a laugh, but I'm curious.

Are there advantages/disadvantages to aluminum heads on stepdown eights?

Can they be polished out, and is the effort worth it?

I've never seen or heard mention of a polished stock head, so doubt if serious Hudnut's would suggest it, but why not?

Thanks for your comments

Joe

Uncle Josh · February 2006

I'm currently running a Hudson straight eight with aluminum head in my 52 Hornet (Hornadore) until the 308 is redone.

I have no problems with it. It has higher compression than the iron head and advertizes 10 more HP ie 138 with single dual-throat (WDG) carb.

I have heard that some people have had problems getting them to hold gaskets but I took mine off to inspect the innards and clean out nut-shells, and put it back together with the same gasket sprayed both sides with hi-temp aluminum paint. Re-torqued it once and have run it two years. No problems.

One reminder, torque and re-torque the aluminum heads cold.

The engine is going to wind up in my 46 Pickup, and I'm swapping the aluminum head for an iron one which I like better mainly due to the HUDSON cast in large letters in the top.

The only polished stock aluminum head I know of is in Dave Norman's 308 powered pickup. Maybe we can get him to comment on it.

Geoff · February 2006

The '34-'35 8's had an optional 7:1 head which was a composite one, with a cast iron base and alloy cover. There was a gasket between the cover and the head, as well as the main head gasket. Then from '36 onwards an alloy head was optional, which was also 7:1 initially, and higher for the Step-downs I believe. The main difference is the lower part above the exhaust valve, to give the higher compression, and slightly smaller combustion space. Unfortunately out here most people back then didn't realise you had to run inhibitor in the water to stop the heads from corroding, and eventually the heads were replaced with iron ones.

Geoff.

Unknown · February 2006

As far as Alum. heads being better than cast iron is only for better heat transfer, so better cooling. The idea being a cooler fuel charge which makes more HP. Some after market heads had a better combustion chamber design also. Makes no diff. otherwise, BUT they sure look neat polished, so why not.

BigSky · February 2006

I have looked around recently and have been quoted $150 to $200 to have the factory straight 8 head I have polished.

GEOFF: Is there really a different gasket to use with the alum head vs cast iron one? also, what is the benefit of spray painting the gasket?

Finally How much could one mill the head and not run into valves hitting?

Thanks,

Geoff · February 2006

Yes, you need to use a steel gasket with the alloy head, to minimise galvanic action. Also coat the studs with a good anti-sieze moly paste, to stop electolysis and oxidation between the studs and the hole4s in the head. My Dad used to have a '36 Graham with an alloy head, the head was solidly locked to the block by oxidiasion in the stud holes. We got it off in four pieces in the finish, threw the engine away and put a Dodge motor in it. But that's another story! The benefit of spray painting the gasket (with high-temp aluminium paint) is to give a better seal - the particles of alloy in the paint embed into the surface of the head, block, and gasket, and take up any stray hollows, dints, uneneveness, etc. and aid in sealing. And remember, alloy heads must be torqued COLD. I can't give you the figure of how much you can machine the head, but this should easily measurable with a dial or electronic caliper - measure from the top of an open valve to the block. Then measure from the head surface to the spark plug electrode, or the lowest point of the combustion chamer, whichever is least, plus the thickness of the gasket, and you should have it. Remember to measure a used gasket, as this will be compressed already.

Geoff.

464Saloon · February 2006

I guess I have seen or heard of aftermarket aluminum heads for Hudsons. Did Hudson make their own aluminum heads and is there any appreciable gain in any of the heads over the stock cast iron. At least with the 308, it seems popular to put on a 262 head to increase compression, but what about the flow? Depending on the design of the chamber, getting that head to close to the valves will impede the flow around the valves and offset any gains made from the increase of compression.

464Saloon · February 2006

That's some good info there. Even if the Clifford head flows better, I still find it hard to justify 899.00. There just isn't that much to a flathead.

50C8DAN · February 2006

The price is probably directly proportional to the volume sold. If Clifford sells 5 of these a year I would be surprised. You might make the argument that if they lowered the price to say $400 they would sell twice as many, it probably still would not cover the entire cost to do the casting and machining.

ratlee2 · February 2006

I have both factory aluminum intake and head and was wondering a couple of things. I was considering polishing them, but do any of you feel it would hurt the value. The last aluminum head I think only went for $50.00 bucks on ebay. I think it would look alot better polished. Any pictures of one polished would be appreciated. The second questions is would it be possible to put some type of sleeve over the shank of studs to prevent the head from welding to the studs? It would have to hold up to the heat, but I think the bolt holes in the head would be large enough to accommodate a thin material possibly Teflon. My last question, and please ignore the ignorance as I am a youngster here, what year was the narrow block used in, and did they make an factory aluminum head for the wide blocks. The head is at my dad's house so I don't have immediate access to measure the width on it right now, but I know it has the casting H-145 on it if that helps to ID it.

Thanks,

Rich

Unknown · February 2006

The head with H-145 on it is from a 308 Hornet which would be a wide block. They made the wide blocks from 1951 to 1956 in all the series. The narrow blocks would be 1948 to 1950.

nick s · February 2006

narrow and wide aluminum and cast iron heads were available

1948-50 were narrow block sixes available in 262 c.i. (super and commodore) or 232c.i. (pacemaker). narrow block cast iron heads were marked 262 or 500. the aluminum is not marked.

your head marked h-145 would be from a 1951 308 (145 hp of the original hornet later heads were marked 308) and would work for any 308 51-54.

Geoff · February 2006

This originally started out as a thread concerning 8 cylinder heads! However, the same thing applies to the later ones - you should use a good inhibitor in the water, and a steel gasket. I don't know about sleeves around the studs though, you would have to bore the holes out, and I dont know if that would be wise, as any removal of metal is going to make the head weaker. Best to use lots of anti-sieze paste around the studs to prevent the formation of oxide due to electrolysis.

Geoff.

464Saloon · February 2006

Has anyone here ever done a group buy on any products for our cars. They do it quite a bit over on an Oldsmobile site I belong to. Alot of suppliers will cut the prices quite a bit if enough people get in on it.

[Deleted User] · February 2006

there isn't much value on the aluminum head ratlee2. so go ahead and buff her up. most hudson people you talk to claim there are good for nothing, i don't agree. with the modern sealants you can put between the block and head you can get a seal. just get past the original way hudson did it.

BigSky · February 2006

Frankmn,

Could you expand on "modern sealants"? what are they and hopefully how have they worked/held up? With all of the technology in new gaskets these days I would really like to have modern gaskets if possible.

thanks,

[Deleted User] · February 2006

was talking to a buddy of mine who used some new gasket from dale cooper, couldn't get the head to come off the block. hooked a chain on the head and lifted the whole block up no bolts now that was stuck good . but ask somebody like steve from uncommon engineering for advice on getting no leaks from that aluminum head.

terraplane8 · February 2006

I remember that a couple of years ago Ivan Zaremba was working with Pat Macdonald in the UK on developing a new cast aluminium head for the 8's that would allow higher compression and better breathing. He posted some info at the time on the H8 Yahoo Groups email list but I haven't heard anything since. The head was 1/2 inch thicker and in two parts like the pre-'34 H8 heads. I have some images of it but don't seem able to post them here, wrong file format. Pete Booz may know where this project is at.

BigSky · February 2006

When one states "use a good inhibitor in the water" is one talking about just antifreeze or is there something else I should look for to add in?

Thanks!

Aluminum Heads - 8's

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