I read in another thread that someone has heard of modifying unposted heads by drilling through the top of the head, screwing a stud down into the head to the top of the combustion chamber, and maybe threading a locking nut on top of the head to keep it in place (maybe even welding the top of the stud to reduce height?)



Has anyone modified their unposted heads with a home-made post to help support the top of the combustion chamber?



I've got big letter ECZ-G heads that are unposted and would love to know of a plausible remedy to posting my heads....



Thanks, Ryan


Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

Jerry Christenson has done this modification. It is pretty straightforward. As I remember he drilled down through one of the rocker stand holes, enlarged it for a 7/16 stud then redrilled the hole for the rocker stand bolt.. Probably not worth the effort unless you are running high compression, nitrous, or a supercharger.

I saw something about using threaded rod screwed in and then the head deck surface machined smooth. Sounded like an idea. But only needed for high compression or blowers. Chuck in NH

Y's guys rule!
Looking for McCullouch VS57 brackets and parts. Also looking for 28 Chrysler series 72 parts. And early Hemi parts.

MoonShadow, 292 w/McCulloch, 28 Chrysler Roadster, 354 Hemi)
Manchester, New Hampshire

I have a page from an old Popular Hot Rodding (?) magazine titled "Bench-Racing Ford's Y-Block", composed of letters sent in re: their Y-Block project series (one was from Jerry C.). It includes instructions for reinforcing cylinders #1 & 8 only (where gasket failures were most frequent) by drilling/tapping through the rocker shaft stud hole, and into the water jacket. Sounds fairly simple/straightforward.

6 VOLTS/POS. GRD. NW INDIANA

Try a search on "Adding a post to a head" This is the way I posted my heads last year. I did not start getting into head gasket issues with a 312 cu in until I added more then 125 HP of nitrous. I would think that posting is not necessary unless you have high cylinder pressures.

  Vic Correnti

I have a set of small letter unposted G heads that have been heavily angle milled (0.175”) and these have an extra post installed in each head. The additional posts were added such that they go through the pads under the rocker stands and between the rocker stand bolts. Because these heads are currently installed on an engine, I don’t have pictures of this particular post installation. But there are some pics demonstrating a similar installation in the thread that is linked below. I’ll add that the adding of any extra posts needs to be done before any head milling is done so any preloading or stressing outwards of the decks can be relieved at the time of milling.

And here’s a direct link to the post that Vic refers us to.

Adding a post to a head

Lorena, Texas (South of Waco)

My G heads have already had .030'' milled off them, and we're going to cut them once more. As little as possible. Hopefully they'll clean up with only a little more milling, but, that's why I'm concerned about them not being posted. Thanks

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie

if your not doing anything special with your engine you have nothing to worry about.the 272 special in 55 had .035 milled at the factory.

Compression ratios and keeping detonation at bay is the key on the G heads when attempting to mill the unposted varieties more than 0.025”.  The 1957 shop manual only recommends 0.010” for cleanup on the G heads so the factory engineers were cognizant of what they had.   When milling the unposted G heads, 9½:1 should be considered the limit for the static compression ratio while also keeping ignition timimg curve attributes reasonable.  That means using a timing light on an accurate damper and not ‘power timing’.  With this in mind, then getting away with more than the customary maximum 0.025” mill on the unposted G heads may be doable.  I’ll let you know more on that as the ported and unposted G heads that are going to be used for the brunt of the exhaust testing have already been milled 0.055”.  Consider this a test within a test.

 

I’ll add that the ECZ-G heads are in a class by themselves when it comes to milling.  The ECL-B and the ECG-A heads would be the 1955 292 heads while the 182HP Special heads for the 272 engines have these same casting numbers.  But as member 314 mentions, the 182HP heads are identified by the 0.866” thick measuring pads on those.  The ECZ-C heads (1956) as well as the earlier 272 heads are cast differently internally and are more robust when it comes to milling than the G heads.  Most efforts at heavier milling from a performance standpoint typically concentrates on the G heads simply because they are in the large valve class and have the smallest combustion chambers available versus what was available on the earlier intermediate valve sized heads.  An unposted G head unfortunately has a pair of deck surfaces within the water jacket area that are internally unsupported which is the root of the problem.  The posted heads addressed this problem specifically.

Lorena, Texas (South of Waco)

Thanks again for everyones input. I appreciate it!





How can I post the inside combustion chambers?

Heber City, UT (15 mins outside of Park City- basically it's in the mountains)

55 Effie