When installing the Chevrolet head, the original bolts were 1/2" with maybe a locating boss at the top like some Model T head bolts. All the adapter plates I have seen and plans I have call for 7/16" bolts. That leaves 1/8"+ between the 7/16 bolt and the hole. The holes in the Chevrolet head are approx .540+. I will be using 1" thick 6061 aluminum stock. You lose 1 thread per 1" going from 7/16 to 1/2. Has anyone used the original Chevrolet head bolts or would it be better to use 7/16 and sleeve the holes in the head? Point of reference, the Chevrolet head is torqued to 50#.
I use 7/16" Allen head socket head screws holding the plate to the block with 60# torque and 1/2 studs holding the head to the plate with a torque of 80-90#. Any less torque and I would blow head gaskets regularly. I use a custom steel plate and have never liked the aluminum versions.
I would rather use the steel but with aluminum, at least I have a better chance of making it with the tools I have. I didn't see that you use studs the first read thru. I like that idea but would need to have the engine in the car to see how much the fire wall would need to be changed to have room to install or remove it. With the engine installed in a custom job that might not be an issue but this is going into a stock setup. My plans are, once the head is where I want it on the plate I am going to put locator pins front and rear so when and if I need to pull the head it goes back in the same spot. I do not know how far I will get with this project but it is good brain exercise! I am working from a set of plans so it's not just making things up as I go along.
I have machined several different chamber type conversion plates from 6061 aluminum and have not experienced head gasket problems ...I used thin paper gaskets ( .015") that I soaked with WD-40 before installation... I am considering using O-rings on a driver application for my 21 speedster ...the 7/16 socket head screws are for attaching the plate to the T block ...my plates use 1/2-13 hex head bolts for the chev. head to adapter plate...I have only ran this conversion on a stand and only for approx. 4 hour total ...always an optimist...Gene French
Socket head screws for holding the plate down. Remember once you put the head on you will NOT be able to retorque these. Heating the plate and retorquing is not a bad idea. As far as the head goes, use studs. Hopefully your plans will include the waterpump outlet as that is another piece that needs to be made. At least these were the instructions and advice provided to me by Mr. Jern a good number of years ago.
1/2-13 will be the way I go not the 7/16 the plans call for. I have worked on one (Model A from Jern) and have been researching this change over for many years.
So is anyone actually producing an adapter plate? I bought a head a couple years ago now, been hoping and waiting for someone to start making these again.
I understand the ease of working with aluminum for a one off, but I too feel a steel plate would be better. I asked our local Metal Supermarket last year and a piece of 8" wide x 1" thick steel bar stock was only $64.
Re the water outlet, I have made one for a plate that I did have. That plate was not made the way I thought it should be so sold it. I don't think anyone is making them now. I am finding the plans I have have a few glitches in them, the calling out for 7/16" for bolting the head to plate is one of them the other is several of the holes for bolting the plate to the Ford block are not quite where they should be. This is going to be a one off as it takes way more money and tools then I have to get a project of this scope off the ground esp making them from steel.
I completed the Chevy head adaption on a 1926 Model T Roadster pickup last fall the adapter plate is cast iron I used the 28 Chevy pushrods the eight original head bolts 7/16 grade 8 cap screws for the adapter my own design water outlet and gooseneck to transition to the radiator cruises along 45 have run it up to 55 with stock ring and pinion and maintains on the Hills temperature ranges from 170 to 190 90 degree weather without a water pump more upgrade still to come dual side drafts and ruckstell so far three to four hundred miles with no major issues
That is the kind of information that helps. Did you take any photos of the plate?
No I did not take any pictures but it does compare almost identical to the jern aluminum plate as far as the gaskets I used the Chevrolet head gasket on top of the plate and plate to block I used the gasket from Lang's for the overhead valve setup the water Outlet I made up does not use a gasket to the two water Ports on the adapter plate
I posted pictures of my adapter plate several months ago ...FYI...my neighbor is currently machining plates from 6061 aluminum ...he is working on chamber programing details currently and hopes to have photos of the finish product including the water outlet adapter and port block off plates soon ...the attached photos are of my plates ...the plate with the finished outer profile is a lower compression than the one that has not been machined on the outer profile...again , these are photos of my plates ...hope this helps to answer some of the questions... always an optimist ...gene french
Thanks Gene. Looks like you added extra water passages to match up with the Chevrolet head between 1/2, 2/3 and 3/4. I was thinking about adding a water inlet to the back of the head feeding off the inlet pipe to get more water in. I will be running an Atlas water pump.
What is the push rod from? What gasket are you going to use between the Chevrolet head a plate, standard or custom made?
(Message edited by redmodelt on August 18, 2017)
(Message edited by redmodelt on August 18, 2017)
the larger counterbores in the Chev. side of the plate are to match up with the large water ports of the original Chev. head ...at the center 2 holes are drilled into the T water passages to match the Chev. water passages ...the pushrod is a 216" chev. pushrod that is shortened and a spherical end machined ...this spherical end fits into a spherical counterbore that I machined into the standard T tappets ...valve adjustment is on the Chev. rocker arms ...for gaskets I used paper soaked with WD-40 ...I plan to machine O-RING grooves in a new plate ...the metal to metal contact and a .010" compression on the O-rings should seal very well and eliminate the problems that seem to occur with the very thick gaskets that are often seen on this sort of application...hope this helps ...always an optimist...gene french
Thank you the information. Any little bit helps.
Scott Hansen has announced the production of his "Poormans Rajo" ... 4 cylinder chev. cylinder head to Ford T block adapter plate in todays classifieds ...I posted pictures of Scotts plate this afternoon ...check these out ...always an optimist...gene french
Hi All, I have just finished building an engine for my Mercury Speedster replica. I have used the neal Jern plate and his gaskets. I was very meticulous in the assembl;e and prep of this but only got ten minutes out of the engine and it blew the head gasket from No1 through the fire ring into the water jacket, I stripped it and put Devcon putty in all the recessed allen head bolts and flushed the plate off ,Installed new gaskets . These lasted probably 1/2 an hour. this time No4 let go the fire ring does not have enough area to seal across the bolt hole and the combustion just chopped out the devcon then the gasket.
The engine run very well , so I will have another go at this . I am going to get a full copper gasket made I have rethreaded the plate to 9/16 unf bolts which locate the head better and will give more tensioning capability.
I am also going to reduce the heads of the Allen Head bolts and make up some aluminium plugs that are a tight fit providing a better surface for the gasket to seal.
Hope that make sense . I will keep you posted Graeme
If you are talking about re-cutting the threads that hold the Chevrolet head on to 9/16 fine, they should be 1/2" coarse thread not fine. I am not sure if Jern used 7/16 or 1/2 in this location. Coarse will give more grip then fine. If you are going to used studs, they would be coarse on the adapter end and fine on the nut end like the Model A. Aluminum should be the same as cast iron, coarse threads. While there are less threads per inch, they are deeper for more grip. Send a PM to Gene F and ask him to be sure.
Some of the Allen heads are in the water passages so except for using stainless steel and sealer, there would be no way to plug them.
Did you have the head and water outlet decked? Your head may not be flat. Did you heat the plate and re torque a couple of times before installing the head?
Olson's Gaskets should have a pattern to make the gasket that goes between the plate and head.
Back ground, I have not done a T but have worked on one of the conversions done to a Model A. The last I heard it was doing fine.
Scott Hansen currently has an advert. on th MTFCA classifieds for his adapterplate system ...always an optimist...gene french