Junk 842 Aluminum Heads

[KevinCav]

I'm looking for one or two sets (or singles) of 842 aluminum heads that are in unusable, or thoroughly trashed condition. I need them for a couple of display engines, and all that matters are how they will look from the outside with valve covers on them.I don't care how many destroyed rocker bosses or detonated combustion chambers there are! Thanks.

[L78M22Rag]

If you find any that are too good (ie usable)... please let me know! Looking for a set for an original 69 L89 Chevelle.
Thanks!

[SS454Elky]

There's a mismatched set on nastyz28 right now for cheap.

http://www.nastyz28.com/forum/showthread.php?t=54995

No affiliation.

[jfkheat]

Kevin, do they have to be the 842s. I may know of a set of bare 074s that are in rough shape. They were offered to me a few months ago but they had some nasty repairs. I can check to see if they are still available if you are interested.
James
BTW, Please fill out your profile with some contact info and a location.

[KevinCav]

Hi Guys,
Yes they do need to be the 842's, because these will be pre-open chamber motors that I will be using them for. Thnaks for trying to help with the 074's, but I really don't have any need for them now. Also I checked into the 842's on the nasty z28 forum and the person said that he would be putting them on e-bay soon. He also said that a crack was detected on them while they were being magnafluxed, but I don't understand how that could happen on an 842 aluminum head. I'll wait to see them on e-bay and I'm still going to keep looking.Thanks for all your help! Kevin C.

[69L72RS]

I just saw these this morning.

http://forums.corvetteforum.com/showthread.php?t=1426386

Hope it helps somone.

Eric

BTW: How can you tell the difference between open and closed chamber heads with them on the engine and valve covers on them??? I have had open chamber 842's before.
Just curious.

[VintageMusclecar]

Eric;

I don't know of any reliable way to ID an open chamber head from a closed chamber just by external inspection.

As far as the "open chamber" 842's, many were converted from closed chamber into "open chamber" back in the day by relieving the plug side of the chamber wall. Old-school racers trick trying to improve flow & flame travel before true open chamber heads were readily available. I've seen many closed chamber heads with this modification, even some cast iron ones. Somewhat risky mod though, as the chamber wall by the plug isn't that thick. You can only safely get about 1/2 way to an "open" chamber before the chamber wall starts to get too thin. Still helped flow & flame travel somewhat, at the expense of some compression & quench area.

Eric

[KevinCav]

Hi Guy's,
The way I have always identified the 842/074 aluminum heads is very simple and it is virtually foolproof. I have used this method for many years, it only takes a few seconds, and can be done easily without having to remove a valve cover.
The first thing I look for when I see aluminum heads on a BBC is to look at the end of the head for a core plug. A core plug on an aluminum head is a sure sign that it is an 842 head. They can be at one end of the head or both ends of the head. Late cast 842's (after about May 1st, 1969) don't have any core plugs in them, so you have to look closer at the head. I have never seen an 074 aluminum head with a core plug in it.
The second thing I look at is the Winters snowflake on the most easily viewed exhaust port. This is a dead give away as to an 842/074 head. On the 074 head the snowflake sits flat on the top of the exhaust port where the manifold/header flange will bolt up, and the height from the top of the exhaust port casting (where the snowflake is cast) to the edge of the where the valve cover gasket sits on the head is approx. 3/4 in. The 842 head is very different in this area and can be detected easily once you have seen a few of them. On the 842 head the spot where the Winters snowflake is cast is slanted up toward the edge where the valve cover gasket sits on the head. The height in this area of the 842 head is only 1/2 in. compared to the 3/4 in. on the 074 head.
These differences in the heads might sound hard to distinguish, especially in a crowded engine compartment, but when you look at a couple of sets of these heads you'll get pretty good at identifying them.