VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1912-1928 1927 Chevy Capitol AA Cylinder Head needed

Hello,

I am new to this forum.
I am a private collector living in Europe / Austria. I also operate my own classic car workshop (www.ok-classic.com). My big passion are US (pre-war) cars.

We are currently working on a 1927 Chevrolet Capitol AA. The car belongs to a friend of mine.
The engine has a broken / cracked cylinder head. Definitely irreparable.Attached are a few pics of the head. There are no casting numbers on the head. Valve diameter is 1 21/32".

Any tips and hints where I could find a non-cracked cylinder head would be highly appreciated.
Also any information regarding interchangeable model years and maybe other GM engines from this period would be of help to continue my search.
Does anyone re-cast those heads in the USA?

I hope that someone can help us to find a good cylinder head which fits our engine.

Thank you all in advance!

Regards & greetings from Austria,
Otto

[img]https://freeimage.host/i/JAqZkN
https://freeimage.host/i/JAqtpI
https://freeimage.host/i/JAqbIt[/img]

Hi OttoAustria

I have been waiting for one of the more experienced members to reply. In the absence of such a reply, I am not an expert, but do own a 27. My understanding is that 26 and early 27 heads are the same. Late 27 have larger valves, I think same size as 28s. A 28 head is quite different, having two exhaust ports and a thermostat housing, but can be used on a 27 engine using a 28 exhaust manifold. The 27 pushrods have to be shortened to use a 28 head on a 27 engine. This is a common conversion here because of the unavailability of serviceable 27 heads..

Earlier heads, I don't know how far back, will fit but except for the 25s had no provision for fitting a valve cover. The 25s had two short valve covers. If any of this information is incorrect, or I have omitted anything, I defer to the expert's opinion!

The early heads including the 27s were notorious for cracking, so good second heads are very rare here (Australia). even though the Chevrolet was by far the best selling vehicle here in 1927, and good heads are priced accordingly. As a matter of interest I had another 27 engine whose cylinder head bore a 1934 manufacture date. Apparently a batch of 27 heads were manufactured then for spare parts. It did not have the Chevrolet name cast into the head, but had another G M manufacture mark, and appeared to be identical to an original 27 head, except that the spark plug holes were sized for 14 mm spark plugs.

franco

Hi Franco,

thank you very much for the information.

I bought two 1927 heads (one early with the smaller valves and one later model with the larger valves) on ebay earlier this week. Both looking like coming out of a barn. The seller did not know if the heads are okay.
I will have the heads checked and tested by an engine builder in the USA prior to shipping them to Austria. I hope that at least one head is okay and can be rebuilt.

If both heads are irreparable I will probably go for a conversion using a 1928 head. As you stated - they are easier to find.

Thank´s again for your support!

Greetings from Austria to Australia,
Otto

f you decide on fitting a 28 head, I seem to remember that you will need the 28 rocker arms too: I don't think 27 and 28 rocker arms are interchangeable.

franco

Isn't there a spacer on the exhaust manifold to change from a left hand steering car to a right hand steering car? So that would be a question for Otto, what country did your car originate? I think its for the pedals. Art

The 28 RHD exhaust manifold is a completely different shape to the LHD manifold. I have not done the head conversion myself, but I suspect the bend in the exhaust pipe where it curves to mate with the manifold would have had to be adjusted on the 27 RHD cars to make it fit to the 28 RHD manifold - don't know if this would apply to the LHD cars.

franco

Hello, the car we are working on is a LHD.
I am in contact with Gary from "Early Chevrolet Parts". He can offer all the parts needed to fit a 28 head to our 27 engine, including an exhaust manifold.
And yes, the rocker arms would have to be changed as well. That´s what Gary told me.
Plus modifying the exhaust.
I will wait for the results of testing the two 27 heads I bought. Hopefully one of them is not cracked.
I will keep you updated.

Thank you again for all your support,
Otto

I have a few 26/7 heads. Where do they crack? I may get them checked so I am not hoarding bad parts. I am in Reno, NV. If your 2 heads don't work....give me a msg. I know I have at least 3 maybe 5 single exhaust heads. Eric in Reno, Nevada, USA

The 27 heads most often crack between the exhaust valves and water jacket of 3 and 2 cylinders as with the one exhaust port they get too hot in this area, this is why the 28 was made a dual port exhaust. As they are a non pressurized radiator system I have had good success having them repaired and brazed up not welded, Converting to a 28 head is a lot of work, your rockers arms, push rods and tappets are all different,