Willys F-Head 134ci Performance Upgrade info

[Lachlan]

I've managed to trawl some information out of the Internet about the ol' Willys F Head, and just how to make it go faster. I thought I'd share it with you guys, as well as some information I've learnt first hand.

http://www.film.queensu.ca/CJ3B/Tech/KamunenEngine.html

The first link basically covers an ignition upgrade, Weber carby swap and exhaust upgrade. Wooders sells an electronic distributor that bolts straight in, and I think it's compatible with ignition control modules (e.g. MSD).

The header is made by Clifford Performance, and although their figures are disputable, it's bound to be an improvement over the cast iron manifold. You could even add a ceramic coating for reduced heat loss.

Most of the upgrades to this engine are pretty self explanatory, but it's worth noting that any one of them on its own probably won't help - ignition, spark and fuel supply all need to be looked at together. You're limited in performance gains by rotational inertia of the crankshaft and valvetrain as well, so to get the most out of this engine you'll need to balance and port it.

http://www.jeepforum.com/forum/f8/bu...f-head-760165/

Second link is to a guy in the States who actually balanced and dynoed his F Head. He netted just under 100hp at 3700RPM, which is no mean feat for an engine that has its roots in the 30s. Note that he didn't use a Weber carb or an exhaust header - so more power is possible. I also talked to a bloke locally who knew of another bloke who actually hotted an F Head up, as much as possible... He got over 100hp from it, and used to race it up sand dunes, much to everyone's astonishment.

Finally, a really easy upgrade is to change from the Carter carb to a Stromberg off a grey or red motor. It's a bolt on fit, and it seems to improve power a little. Try to find ones jetted for the grey motor though, because the F Head seems to be sensitive to jetting and venturi size - I replaced mine with a smaller venturi and seemed to regain my bottom end torque.

All of these upgrades are possible in your shed, and with a basic machine shop for your balancing work. If it's all done properly, you can actually equal or exceed the original 144ci Falcon 6 found in early Combat 6 jeeps. At the very least, this serves as inspiration for those of us crazy enough to keep the "tractor engine" F Head!

Hopefully this will all be useful to some of you, and one day I hope to follow up with a pictorial of my attempts at performance upgrades - when they happen!

[cj4a nz]

cheers
I just need to keep mine going hurmph

[Lachlan]

Haha slow and steady mate - these engines take a lot of TLC to get running just right, but once you get it there they'll serve you for many years to come! Dad and I have been driving a '62 CJ6 daily for about a year now, and we've only just got it to run reliably!

[Lachlan]

Sorry if I'm beating a dead horse, but I've installed the electronic distributor, manufactured by Omix-Ada. Starting is much improved, as well as throttle response, and the engine seems to pull smoothly from a lower engine speed (about 1500RPM in 3rd). It also seems to handle richer idle mixtures. Power is about the same, but responsiveness is noticeably improved. I imagine a hotter coil could be used, and a slightly larger plug gap, which would allow for richer mixtures, better fuel burn and hence more power. I'll take some pics tomorrow.

[cj4a nz]

lachlan wondered what you were up to
it's not a dead horse
where did you get the dissy from and any numbers etc on the packaging
my motor in bits and have webber 32/26 carb now need more motivation but second cold this winter aint helping
pic's pic's
Warren

[Lachlan]

This is how it looks all set up...



The blue and black wires are the positive and negative wires from the distributor. Dead easy to wire up.



This is a view of the internals.

Installation was breathtakingly easy, and most of your time will be spent timing the thing. I reckon this system would go really well with an ECM, mapped against manifold vacuum and engine speed.

I'm not sure if it's a quirk of the distributor or my engine, but it doesn't like starting with full advance. Sometimes I've had to retard the timing to static, then start it, then re-advance it. My idle also changed, and it won't drop below about 800RPM, but based on the improved responsiveness, I don't really care.

Idle misfires are basically eliminated, and the engine is smoother and more responsive at all engine speeds - right to the redline. Peak power is basically unchanged, but I think if you installed a hotter coil and widened the spark gap you'd gain a little bit.

[Lachlan]

Another update - after running the electronic distributor for several weeks, the starting issue got progressively worse, and fuel consumption increased from about 13 L/100km to 18 L/100km. That's over a 200km round trip, mixed highway and city mileage. I've sinced reinstalled the original distributor, and both problems disappeared.

My guess is the electronic distributor needs a hotter coil; both of the issues mentioned above are symptoms of a weak spark, and we tested to make sure the spark was consistent. I'll be home on Wednesday, so if anyone is still watching, expect another test run with a hotter coil within the next week.