Mickey Thompson’s 427 Ford Hemi V8–and its fascinating secret

Mickey Thompson Hemi ThunderboltYes, it’s a hemi. No, it’s not a Chrysler. It’s a big-block 427 CID Ford hemi engineered by Mickey Thompson in 1963. But wait until you see inside—you might not believe your eyes. 

 

 

For MCG, this story begins in January of 2010. As Detroit Editor at Hot Rod Magazine, he happened to be riding a desk at the Los Angeles office one day when a phone call came in. Clyde Dedrick, a longtime drag boat and vintage Top Fuel guy, was asking if we’d like to come see a rare engine in his collection: a Mickey Thompson 427 Ford hemi, one of only a handful ever made. Naturally, MCG grabbed his camera bag and drove right over.

We spent an entire day at Clyde’s shop, where he graciously allowed us to take apart, put together, and run our gummy mitts all over his rare M/T hemi, which had originally powered a ski boat back in the ’60s. While we were there, we shot enough photos of the engine to illustrate a dozen magazine stories, and one such feature appeared in the August, 2010 issue of Hot Rod (story online here). It was a fun day and it made a nice story, but there was at least one feature in the engine we weren’t prepared for.

Most gearheads are already familiar with Mickey Thompson and have at least heard of some of his company’s many innovations, including the aluminum hemi heads for both Pontiac and Ford V8s. So, without further introduction: Here’s an examination, in words and photos, of the M/T Ford hemi V8—including one detail that may amaze you.

 

Heads Ford vs 392In hot rod lore, the story often goes that Thompson adapted production Chrysler head castings to fit Pontiac and Ford blocks, but in fact they are entirely different pieces. At right is a stock Chrysler 392 CID head, with the M/T aluminum Ford head on the left. Thompson shrewdly recognized that the Chrysler, Pontiac, and Ford FE big-block V8s shared similar (but not identical) bore spacing and head bolt patterns, which allowed him to borrow the general layout and a few bits of hardware for his hemi conversions.

 

assembled head Ford HemiThe cylinder head and pedestals for the twin rocker shafts attach using the production FE Ford block’s head bolt locations, 10 per bank. The exhaust rocker arms (lower shaft) are custom aluminum forgings, while the stubby intake rocker arms (top shaft) are production Chrysler 392 parts.

 

Ford Hemi Combustion ChamberAnd here’s the hemispherical combustion chamber of song and story. Note the conventional spark plug location and the soft copper sealing ring that fits in a machined groove around the circumference of the chamber. Contrary to typical American V8 practice, the intake and exhaust valves on the M/T Ford head are the same diameter, approximately 2.00 inches. The 392 Chrysler used 2.00-in. intake and 1.75-in. exhaust valves.

 

Ford Hemi pushrodsFairly interesting engine so far…intriguing and creative, but nothing too outlandish, right? Now check this out: articulated three-piece pushrods. To make room for larger, straighter, greater-flowing intake passages, M/T took a radical step and split the pushrods into three segments that snaked around the ports.

To help stabilize the wobbly-looking assembly, the lower segment’s ball end is captured in a cage that is brazed to the top of the roller lifter body. Meanwhile, the middle segment runs in a fitted bore in the cylinder head casting. The lifter bodies are linked to each other to prevent rotation on the cam lobes, and valve lash adjustment is handled by the threaded ball insert in the uppermost pushrod segment.

 

cylinder head pushrod boreThe red arrow points to one of the fitted pushrod bores. Note the small oil orifices drilled diagonally into each of the pushrod bores, and check out the big, square intake ports.

 

installed pushrodHere’s a closeup of a roller lifter installed in the block, showing the brazed cage that retains the lower third of the pushrod to the lifter body.

 

Ford Hemi Valve coversM/T’s signature cast-aluminum valve covers for the Hemi Ford are the same pieces that fit on production 331 through 392 CID Chrysler Hemi V8s, and the M/T Pontiac hemi, too—the covers and gaskets are all interchangeable. They also fit the aluminum replacement cylinder heads M/T produced for the Chrysler hemi, naturally. The spark plug tubes are Mopar replacement parts.

 

Mickey Thompson was blessed with factory Ford sponsorship in 1964, and he prepared at least two cars for drag racing that year equipped with his hemi conversion: a ’64 Thunderbolt Fairlane driven by Jess Tyree (shown in the lead photo at the top of this page) and in his own supercharged dragster. Here’s Mickey with his class winner trophy at the 1964 NHRA Winternationals.

Did M/T’s articulated pushrod system have real potential? Seems doubtful. We can only imagine what the monkey-motion linkage would look like on a modern Spintron—pretty scary. Engine builders of today send gobs of time and money making pushrods as short and stiff as possible, and here M/T went off in exactly the opposite direction. On the other hand, the M/T Ford Hemi probably wasn’t required to turn much more than 6,500 rpm, where the wacky valvetrain might not be too horrible a handicap.

Either way, the M/T Ford Hemi was soon dropped. Ford had its own hemi V8 in the works, the fabulous SOHC Cammer V8, which solved the pushrod problem by eliminating them. (Read MCG’s exclusive Cammer history here.) Mickey himself had considerable success with the factory Cammer engines in multiple venues—including his all-conquering 1969 Mustang funny car team. But M/T wasn’t done brewing up his own unique engine and vehicle designs, and we intend to cover some of them in future stories.

 

rockers

26 thoughts on “Mickey Thompson’s 427 Ford Hemi V8–and its fascinating secret

  1. Interesting. I have a good amount of MT Hemi Pontiac stuff including the only known surviving complete Hemi engine in running condition. Neat stuff.

  2. The articulated push rod was also used by Bruce Sizemore when he made a 3 piece Cleveland cyclinder head to go on his Ford 300 ci 6 cyclinder. He ran it in a Pro Stock Pinto back in 71′ and would run times that kept up with the V8s

  3. Legendary engine designer Phil Irving made two piece push rods in the F5000 Holden motor.
    His theory was if they were going to keep breaking push rods he might as well design the point of the break.

  4. Wonder if it might have been simpler to go to 2 pushrods and 2 rockers for each exhaust valve, as has been done with some European production engines. This was almost done with the last Chrysler hemi, but it never got past the drawings stage before Tom Hoover noticed that a slight tilt of the head allowed the conventional hemi valve train layout.

  5. Tom Hoover ran a Shotgun Ford in Amarillo around the early 70’s.
    We had a 354 with O-Rings machined in the heads and used shim gaskets. This was a super charged altered on nitro. It worked very well.

  6. Sorry about the confusion. I was referring to Tom Hoover, the Chrysler engineer and not to Tom Hoover, he AA/FD driver. (I don’t believe the two are closely related.) Though, even today, you might run across the Tom Hoover to which I referred at the strip, where he accompanies his motorsports active son.

  7. How about his experimental compressed air Funny Car, I think from 1971? That was an even more interesting concept that did not go too far. His son Danny told me it had great potential and made good power.

  8. Actually, if you think of the middle portion of the setup as more of a lifter in a bore in the head, you have two very short, stiff pushrods working between two sets of lifters. Maybe not so dumb after all, that Mickey Thompson.

  9. In the 80’s I was running a Monza BB/FC and found and purchased a couple Micky Thomson 5/8 stroke CAST crankshafts, hard to balance but never broke one, these were brand new, looked great. Now I had a ton of Milidon complete steel heads, at that time I had about 7 or 8 sets left, Donovan block and steel heads, the heads had various valve combinations, 2″ int X 1 1/2 exh, 2″ int X 1.750 exh, 2″ int and exh, and 2 1/8 int X 2″ exh.
    I purchased a bunch of steel stuff when everyone was going over to late models, they were giving the stuff away.
    Ron Luks

  10. wE LOST A GREAT MAN TO EARLY ,PROB. TO GREED ALWAYS FOWWLOWED HIM AS A KIDi REMMEMBER HIS STREAMLINER WELL MISS YA STILL MICKEY,HERES TO YOU AND THE MISSES

  11. Over the years, I’ve read about Tyree’s hemi equipped T-Bolt, but never heard how it actually ran compared to the high riser cars and especially the Mopar hemis. Once hemi equipped, the ’64 Chrysler cars had a big advantage, particularly at the high end. Did Thompson’s hemi convert measure up?

  12. I imagine that the unusual push rod design changes the “assembly procedure” some. Push rod / lifter set ups must go on with the cylinder heads. Any insight on this ? Chrysler FirePower my favorite engines,I run 3 of them.

  13. When I was in High School in the 80’s we had a two seater speed boat, which had a 427 Ford Hemi in it. It was the fastest boat on any lake in the area. Most people don’t believe me when I tell them it had a Ford 427 Hemi. My step dad later sold the motor to a guy to use it for tractor pulls (I think). Anyways, I wonder if this could be the same engine.

  14. Mickey was a very talented man its a shame he & his wife were taken so early.

  15. I was interested in the 428 super cobra jet hemi enginne that was built by Mickey Thompson in 1968

  16. Was a great fan of mickey Thompson and i loved what he did to the ford super cobra jet engine, like to put it out there to all the others

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