Chevrolet ohv head on a Ford Model A block adapter plate

[GPierce]

A machinist friend that doesn’t post on the internet is looking for information on the Chevrolet ohv head on a Ford Model A block adapter plate.
PM me or post if you can help.
Thanks
Gilbert

[Big hammer]

Didn’t Bill Stipe build one ? Look at the Stipe web site!

[GPierce]

I found this site:
https://thoughtintensivedesign.wordp...valve-model-a/

[GPierce]

Originally Posted by Big hammer

Didn’t Bill Stipe build one ? Look at the Stipe web site!

Thanks, I found an explanation on Bill Stipe’s web site about how he did it. He used a later Chevy head. Would like to find the adapter plate design used with the late 20’s head.

[BRENT in 10-uh-C]

Originally Posted by GPierce

Thanks, I found an explanation on Bill Stipe’s web site about how he did it. He used a later Chevy head. Would like to find the adapter plate design used with the late 20’s head.

I think I may still have this one from my father's estate. It was '28 Chevrolet on a complete running A engine when we got it some 20-25 years ago. There was even a website that outlined when Herman built it (-and I copied that and put it into PDF for you to read). I am pretty sure dad removed the head and related stuff from that engine and just stored it. I will try to look in the next few weeks if that meets your timeline to see if it is still in our possession.

.
.

[nkaminar]

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Up through 1927 Chevy used a head with one exhaust port. All the exhaust was collected inside the head. In 1928 they went to a head with two exhaust ports and an external manifold to collect the exhaust. In 1929 they went to the 6 cylinder motor.

My first car was a 1927 Chevy. My dad recounted that after 1928 people would put the 28 head on the earlier Chevy motors for more power.

My friend in Campbell just sold a Chevy head that was set up to mount on a Model A. The overhead valve mechanism had been modified for oil lubrication from a pipe leading up from the engine block. The original Chevy just had a pad on top of the valves that was saturated with oil and a stamped metal dust cover. Getting the head is the start of the project and there is a lot of work to be done after that. If you can find a Chevy head that has had all the work done to bolt to the Model A engine I think you are dollars ahead. (Or should it be dollars a head?)

[BRENT in 10-uh-C]

Originally Posted by nkaminar

Up through 1927 Chevy used a head with one exhaust port. All the exhaust was collected inside the head. In 1928 they went to a head with two exhaust ports and an external manifold to collect the exhaust.

Neil, based on my understanding, you are correct that prior to 1927, all 4-cylinder Chevrolet engines were a single-port design however I believe the two-port was introduced sometime in early 1927 for commercial truck use and for the Capitol series beginning mid-year in 1927. As I understand it, the biggest difference between 1927 and 1928 two-port heads was the '27 head used a 1:1 rocker arm whereas the '28 head used a 1.5:1 head. Can you confirm this?

[nkaminar]

Hi Brent,

Sorry, cannot confirm changes if rocker ratio. My dad has been dead for many years and I was 14 when I bought that 27 Chevy, which was many many years ago. I will ask my friend in Campbell to see if he knows.

My friend in Campbell does not know the answer either. It sounds like the guy with the red Model T, below knows that the more modern heads were 1.5 to 1.

[AZ_Nick]

That's a great article Brent provided. I can only add that the adapter plate could be vastly improved with modern CNC and 3D design to eliminate the step in combustion chamber. I plan on doing this with an Olds head in the future but right now I'm buried in paying work. Please post back if there is anything your friend needs after studying Brent's article.

[GPierce]

Thanks everyone for the input. My friend is a retired machinist with multiple A’s. He has the Chevrolet Head and would like drawings of the adapter plate and or pictures. He wants a new challenge I guess.
No hurry Brent and I as always appreciate your input.

[redmodelt]

Originally Posted by BRENT in 10-uh-C

Neil, based on my understanding, you are correct that prior to 1927, all 4-cylinder Chevrolet engines were a single-port design however I believe the two-port was introduced sometime in early 1927 for commercial truck use and for the Capitol series beginning mid-year in 1927. As I understand it, the biggest difference between 1927 and 1928 two-port heads was the '27 head used a 1:1 rocker arm whereas the '28 head used a 1.5:1 head. Can you confirm this?

I have worked on a Model A with the Chevrolet overhead conversion and made an adaptor plate for my Model T. The 1.5 should be correct. Chevrolet also went to bigger valves. The single port were about Model T size. You used to be able to buy modern rocker arms from; Billy Possum Rides the Web
This link has a mix of both T, A and name brand overheads; https://www.google.com/search?newwin...&bih=927&dpr=1
The ones the guy was making, he passed away a number of years back, required a special head gasket to fit the shape of the valve cutouts in it between the adaptor and head. The Thunderbolt plates came in a couple of different compression ratios.

[BRENT in 10-uh-C]

Originally Posted by AZ_Nick

That's a great article Brent provided. I can only add that the adapter plate could be vastly improved with modern CNC and 3D design to eliminate the step in combustion chamber. I plan on doing this with an Olds head in the future but right now I'm buried in paying work. Please post back if there is anything your friend needs after studying Brent's article.

Nick, we also have a Model-T plate that uses a 'D' shape but as I understand it, when the combustion chamber was modified with the plate to a 'D' shape, it had head gasket issues between the head and the plate. Mark, did you have any issues with the 'D' shaped plate??Thoughts??

[redmodelt]

At the time we worked on it, were still able to get a replacement gasket. I don't recall any issues with the plate itself, other than maybe a water leak issue and worn rocker arms. The aluminum plate needs to go through several heat/cool cycles before the head is attached. Once the head is installed, the plate can't be retorqued.

The other issue, rocker arms; They were the original Chevrolet and think they were doing the same as my adapter setup, needed to be ground with correct angles to rotate the valves, those pads were badly scored and were too thin. That is why they were replaced.



You could also do a search of " Jern Thunderbolt Model A conversion" https://www.google.com/search?client...l+A+conversion

If someone does this conversion, make sure they get the water outlet adapter and expect to take more time than would be involved with just installing a ready made overhead.

[Will Ziegler in LI NY]

Neal Jern made the Jern Thunderbolt kit, it was parts to put a Chevy OHV on a model A. I know there were some articles on in in the SOSS magazine. Do an internet search fro Jern Thunderbolt.

[AZ_Nick]

A few pictures of the adapter plate and graphite gaskets. A friend built one a few year ago and had sealing problems, he ended up having a head gasket made in the NW with copper sealing rings. I can't recall the place that made the gaskets but will find out. Cylinders 1 and 4 have a step as shown in the close up. My thought is to soften that step on the next one to eliminate heat risers in the chamber.

[noboD]

'28 is the only year with a valve cover too.

[redmodelt]

Valve covers started before 1928.

Wonder if part of the not sealing is because it was not heated and torqued several times before the head was installed? Could that place have been Olson Gasket?

[Dodge]

Yes the rocker arm ratio was more on the 1928 head. I went to Neal's place before
he passed away, nice guy. He did more of them for Model T's than A's. As I recall
you used a OHV conversion gasket for either T or A on the block and the Chev. gasket
on the head side.
I also have one of these heads I would sell if any one is interested.

Dodge

[Retson the Racer]

Originally Posted by Dodge

Yes the rocker arm ratio was more on the 1928 head. I went to Neal's place before
he passed away, nice guy. He did more of them for Model T's than A's. As I recall
you used a OHV conversion gasket for either T or A on the block and the Chev. gasket
on the head side.
I also have one of these heads I would sell if any one is interested.

Dodge

Still have it?

[Ray in La Mesa]

Just for info, I, too, have a couple 1928 Chevy motors w/ heads for sale, email me.