Willys F134

[Single-Phase]

Hey folks, I've been trying to build one of these since 2018 (college student's budget) and finally got one buttoned up.
Back in the early 2000s, a friend played around with a few of these while he was racing with them. One of them he milled .125" off the head, ported, and polished the exhaust ports, and topped it off with a homemade carb adapter (R2g). On another one, he experimented with a homebrew NOS system which worked fairly decent.

This is fhead #3. The best core I managed to start with. Here it is out of my 3b decked out with custom HEI, power steering, and an RV2 air compressor I used for OBA. It burned and leaked oil so bad I was running 140wt gear oil in it.



Took a total of .137" off the head, opened up the intake passage, cut the guides for a positive seal (using caterpillar seals), and 4 angle valve job.



Bored and honed to .030 for a final size of 3.155
Decked the block and cleaned up the exhaust ports some.





Had a custom cam ground for it. Compliments to Schneider Racing Cams for taking on the project.



My buddy passed me the torch so to speak, so I topped it off with the r2g. The carburetor in question is the large base version. I don't expect it to do anything on the bottom end but I had originally built the Jeep for racing anyhow so that's not a deal breaker.




I know these are fairly popular in Florida with the swamp buggy racers.

[Single-Phase]

I finally got the Jeep built and broke in the F134. It runs like a scalded dog. Seems to really pull from ~2500 and zings on up to 6k no problem. Huge difference vs a stock F134.

[miniv8]

Cool engine, thanks for sharing

[PackardV8]

The F134 is a stout little engine. The first question usually asked, "Why an F-head? Why not put the exhaust overhead also?" A look at your excellent photos tells the tale. With the tiny 3.125" bore, there isn't room for two valves of the correct diameters. By giving all the bore to the intake, a much larger diameter can be used, thus more power than two smaller valves.

A side note is when Studebaker Engineering was going through the same process, converting a 3" bore flathead to OHV, they wanted to use the F-head, but marketing perception was against it. They tried to fit both valves OHV with mixed results. The first design put too much heat into too small a space, valves burned and the castings cracked in use. A casting redesign solved that, but proved there was still a good reason for F-heads over small bores.



The gasket shows how the exhaust valve hangs over the top of the block.

[Truckedup]

My wife assembling the 134 F head in our 51 Willys truck......

[Ken_Parkman]

I flowed one of those out of sheer stupid curiosity. It's really a character flaw.

Figured out how to put it on the flow bench which was a bit of pain because the bore is so small and the chamber goes way off the side. Fortunately I made a top plate and small bore fixture for the Tornado, and it was pretty close, but I had to cut the plate and turn it sideways to seal against the crazy combustion chamber. It's OK, still usable for the Tornado.

Completely untouched old casting. Flowed cylinder 1 and 2 to see what difference the distance from the carb makes. This was with the other valves in, so all the flow was coming through the carb flange which had a putty radius. So its representative of testing a head with the intake manifold on a normal engine. Could not go any higher lift than .500" as the valve hit the deck.

Lift cyl 1 cyl 2
.100 60.0 62.4
.200 105.3 105.9
.300 127.1 130.1
.400 135.8 140.4
.500 140.3 143.5

[frnkeore]

I had a Jeep F150, with this engine in it. If it over heated very much, it would blow a head gasket.

I had it from '76, until about '80 and blew 3 or 4 head gaskets. The last one was do to the generator bracket loosening, on the fwy.

[Truckedup]

The F134 is a stout little engine. The first question usually asked, "Why an F-head? Why not put the exhaust overhead also?" A look at your excellent photos tells the tale. With the tiny 3.125" bore, there isn't room for two valves of the correct diameters. By giving all the bore to the intake, a much larger diameter can be used, thus more power than two smaller valves.

A side note is when Studebaker Engineering was going through the same process, converting a 3" bore flathead to OHV, they wanted to use the F-head, but marketing perception was against it. They tried to fit both valves OHV with mixed results. The first design put too much heat into too small a space, valves burned and the castings cracked in use. A casting redesign solved that, but proved there was still a good reason for F-heads over small bores.



The gasket shows how the exhaust valve hangs over the top of the block.

That's why the Brits used wide angle hemi heads in bikes as a way to stuff big valves in a small bore.
The 134F has a 2 inch intake valve, quite large for the engine size...

[PackardV8]

Yes, Willys or Studebaker could have used the BMW/Bristol pushrod hemi conversion.

[Single-Phase]

I flowed one of those out of sheer stupid curiosity. It's really a character flaw.

Figured out how to put it on the flow bench which was a bit of pain because the bore is so small and the chamber goes way off the side. Fortunately I made a top plate and small bore fixture for the Tornado, and it was pretty close, but I had to cut the plate and turn it sideways to seal against the crazy combustion chamber. It's OK, still usable for the Tornado.

Completely untouched old casting. Flowed cylinder 1 and 2 to see what difference the distance from the carb makes. This was with the other valves in, so all the flow was coming through the carb flange which had a putty radius. So its representative of testing a head with the intake manifold on a normal engine. Could not go any higher lift than .500" as the valve hit the deck.

Lift cyl 1 cyl 2
.100 60.0 62.4
.200 105.3 105.9
.300 127.1 130.1
.400 135.8 140.4
.500 140.3 143.5

Great information. This is the kind of tech I was hoping to find. I thought about using sbc 2.02 valves but in my opinion, the 2" valves already flow more than enough.

I wish I'd done more measuring to figure out the compression ratio of my engine. I used a thin head gasket like a fel pro and since I couldn't find the compressed thickness, I was going to take the head back off after torquing it down to measure but ended up not doing it.

Some notes from ~5 years ago...
The cylinder head was stamped 6.9. It had 75cc combustion chambers. From what I found every .010 thou = 1cc. I took some measurements and came up with a 6.94:1 CR with the engine in stock form. After milling .125 off it I came up with 62.5cc.

I have a second Fhead that I will eventually build and it will be a bit hotter than the current one...
The rotating assembly is somewhat balanced on it and I decked it .024" and shaved .125" off the head. I want to have custom valves made and roller rockers.




Homebrew header. This was the third iteration of it. It's ugly but I had no idea what I was doing. It works though.

[Ken_Parkman]

Yes the valve size is certainly not an issue. It is far bigger than the port, which is why the flow curve is so weird, basically flatlined at .300" lift. Porting would help much more than valve size, but hugely hard to get in there. The intake valve is so large it overhangs the bore and hits it!

[PackardV8]

Yes the valve size is certainly not an issue. It is far bigger than the port, which is why the flow curve is so weird, basically flatlined at .300" lift. Porting would help much more than valve size, but hugely hard to get in there. The intake valve is so large it overhangs the bore and hits it!

Turbocharger!

[Single-Phase]

Pretty much done with the revamp of the 3b. I'll keep this updated as I experiment with these engines.