How much Horse Power?

I agree. The older jeeps were never meant to travel from state to state at 70 + miles per hour like our cars do. Even outfitted with a snorkel kit, they are not submarines. Take them in over their heads and they will get stuck. It is however a great 'universal' vehicle. It will do things above and beyond what any of my cars can do, when I take it into the woods...Would I want to run an F-134 steady at 70 mph for 2-3 hours? I think I would be asking for problems if I did. They handle like crap (at least mine does) and in no way compare to the traction control on my 2010 Acura TL. I could think of no worse engine to want to increase horsepower on than the F-134. It was made for torque and power. Just take a look at the size of those gears in both the transmission and transfer case. You won't find anything like that except on construction equipment. Can one break them? They get broken often usually through misuse or neglect. Save a good engine for someone that needs it to perform as it should and put something more tuned to horsepower and speed in it. I've never seen a v-12 CJ5...

 

These are putter along at 55 mph or slower, and watch the scenery, and smell the roses vehicles. If you want to run at 70 to 80 mph, then you probably should go a Porche or something. But then you would miss all that scenery and those roses. It is a choice thing. I'm getting old. I like looking at the scenery and smelling the roses, any more.

 

Back in the 70's I had a MB, bored 60 over, head shaved , block decked etc.
It had more power than a friends '61 CJ5.
I just couldn't fix the rear main seal oil leak, about 5 attempts, even profesional work didn't fix it.
Ended up with a 198 V6 in it.
Never looked back, over twice the power, better gas mileage and it would do highway speeds after the overdrive install.
Then again, on the MB, I had to change out the complete drivetrain to get there.
I think I made it about 3 blocks with the origional 23 -2 rear axle before it broke an axle shaft.
One that I wish I still owned.

 

OK,
I get the picture. I'm committed to the f-head (already bought the rebuild kit), but I also would like to get all the potential it's capable of. I don't have a long commute anymore, or have to do much hiway driving, and if I do I have another vehicle, so I still think this will suit me fine.
thanks for all the comments.

 

I love my F head......With 33's I can bang mine up to 55, I feel it could do it all day long, as long as the roads are not hilly or steep. They are pretty simple engines and can be used as a great learning tool. Putting one together and running it is very satisfying. Good luck on your build.

 

Ok, like the others, the easy way for more power is an engine swap, but since you're committed... The easiest, cheapest thing you can do is shave the head. You're going to want to have it resurfaced anyway for the rebuild, but get out the dial indicator and figure out just how much you can take off it before you have valve interference issues. Getting the compression ratio up will help your cause.
The next easiest step is to do some mild port work. This is something you can do yourself with a die grinder. Smooth the ports and try to remove material off the short radius side of the ports.
After that, have the cam reground. The more lift and duration you have, the more air you'll flow, the more power you can make. I'm not in the business of grinding cams, but there are any number of cam grinders out there that can help you meet your performance goals. Depending on what you want to do, the lift, duration, lobe separation angle, valve timing, etc can be altered to produce max power at different engine speeds (do you want a low end stump puller or a high RPM screamer).
You're already boring the engine so that will help marginally, and in intself, bump up the compression ratio just a bit. If you really want to get nuts, you can offset grind the crank for more stroke, but then at the least, you'll need custom made pistons or rods.
Others have mention forced induction, more air means you can burn more fuel and make more power, but get out your wallet....
Just remember: Good - Fast - Cheap - Pick 2

 

This really is true. If your Fhead is needing a rebuild anyway this is the way to go. I did in my 3b, added a 4 speed t-18 as well. Made it a really fun Jeep to drive.

 

In a paragraph relating to a F head? The only screaming I see is from people trying to dodge flying rod pieces. Realizing of course the mix could also include a few block fragments and possibly some portions of the pistons.

 

Boring it out will increase your displacement, but an .030" overbore isn't all that much. It changes your 134 ci motor to a 137 ci motor. You could get a lot more power by having the crankshaft ported and balanced ($$$,) with a hotter cam, and by shaving the head to reduce the size of the combustion chamber to boost the compression ratio.

The Solex carburetor isn't a performance upgrade. It's really more of "side"-grade for someone who can't otherwise find a cooperative stock Carter. However, they make a Weber 32/36 two barel carburetor adapter kit for the F-head ($330,) and that will maximize things on the intake side (since there's nothing you can do about the intake manifold, given that it's cast into the head,) but there are a few headaches that come with installing it.

You can make the system freer-flowing on the exhaust side by installing performance headers ($350 or thereabouts.)

You can also turbocharge the F-head. Someone's gone and done it ... but be warned that it's a DIY project.

I have an electronic ignition on my F-head. An MSD Street-fire box feeding an MSD Blaster II coil, with a Pertronix hiding under the distributor cap to time it all ($325 including the set of Magnecor helical-wound plug wires required for EMI suppression.) It doesn't increase power, since you're firing on whatever fuel/air charge gets dumped into the cylinder, and the F-head's combustion chamber design puts the spark plug about ten miles away from the bit of the combustion chamber that does all the work anyway. What an electronic ignition buys you is a more consistent firing and easier starting.

Can you turn a 72 HP '30s tractor motor into a 100HP '30s tractor motor? Yes. Would you want to? Eh ... probably not.

Why? Well, consider that the F-head is a seriously undersquare motor with the finest lubrication system technology the '30s had to offer. It has a redline RPM of 4000, but you can't run it that fast for very long because the lubrication system just can't keep up. Its maximum sustained RPM is around 3200, and it's really only happy below 3000 RPM. With the typical CJ5's final drive ratio of 5.38:1, you hit 3200 RPM at 56 MPH (on 32" tires) ... but the engine is happiest if you keep your speed to 50 MPH. You could extend that top speed to 75 MPH by installing a Warn/Saturn/Husky overdrive (but you couldn't get there anyway, since the vehicle has the aerodynamics of a barn, vague steering, worse brakes, and a suspension setup that wouldn't look out of place on the bottom of a chuckwagon. The real beauty of the overdrive is that it lets you do the safe 50 MPH while keeping your RPMs to under 2150.)

 

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He probably means polished and balanced.

Some port work on the head would help, but you have to know what you are doing to make a big difference. All this stuff is covered in the hot rod literature.

 

Back to my post #16. Just about anything is possible if you want to throw enough money at it. If you are going for some class record, that may be worth it, at least to some people. There is a local doing that with flathead Fords at the salt flat and it is interesting to see what extremes one can go to to TRY and keep the heads on one.

I can tell you that you will not pull 1000 hp out of a 134 with stock rods, crank or pistons. That would need a pretty high boost on a supercharger which would send all those parts someplace they shouldn't be. At that point I would also suspect there would be some major problems keeping the head on an F head. However, probably nothing a CNC block couldn't cure. Again, if you have enough money------

Heck, you could even buy one of those Wilson, WY restored vehicles to pull the trailer for it.

 

Consider the old Jeeps were tractors that can go down the road at a fair speed. That and the durability plus ease of fixing was a potent combination in it's day. Basically a small version of the Unimog. They were sticking bigger engines in them back in the 50s for a faster home brew system. Also remember an engine is basically an air pump. The better the flow the better the power, but these old F heads will only squeeze a bit more power.

 

I remember some of the small oval racers back in the late '60's were trying some of the GMC v6's in thier cars.

Interesting uses of chains at times to keep everything together.

 

Yes, I misspoke. Power could be gained by porting the intake and exhaust, and some can be had by lightening the crankshaft and flywheel.

Mind you, given that the head is held on by bolts that go directly into the cooling jacket, I'd start to worry about head gasket life if one were to undertake internal mods to the engine to seriously boost its power.

 

How about cross-drilling the muffler bearings, and going to a synthetic blinker oil?

 

There always has been a six cylinder class in stock car racing. They use them at the local dirt track. They even doing great things with the inline sixes. There is a place out west, maybe Tucson that is using the Ford 300 as a serious drag race engine.