Performance Options

My opinion regarding that Clifford claim of 20% increase in power is way overly optimistic. I'd be suprised if they could back up even half that claim. There has to be a lot more done to a Willys 134ci in combination with a header to get that kind of power increase.
-Donny

 

A header may give you 1-2 hp at certain rpms. That claim of 20% is knee deep bs. It will sound cool but nothing is really going to give any performance gains to an F-head. Lightening up the Jeep as much as possible is the best way to actually make an F-head drivable. The biggest gain in an OD is being able to split 2nd gear. I have never seen any real gain in the top end but it does make it seem like it won't blow up any second if you are going over 50.

 

The most power I've gotten out of an F-head was by drastically milling the head, opening up the intake ports and adding a large 2bbl carb, but all power gains were in the top end. It made the bottom end relatively worthless, but the power increase above 2500rpm was substantial. It reminded me of the powerband of an old aircooled 2-stroke.

I've often thought about the possibilities of using two single barrel carbs with the second carb set up as a progressive secondary. It would keep low RPM airflow and fuel mix in check through a single carb, but the high rpms would be allowed to breathe freely. Some day.

 

I think you'd be better off using a progressive 2 bbl...something like the Holley Weber they used on Pintos. With two separate carbs I thing you'd have uneven fuel distribution when running on just the primary carb...

 

How about fuel injection? There is a throttle body available for the GM 151 and for the AMC 150. Either could be adapted to the 134 as easily as a Holley-Weber. The Redline Weber kit for the 134 is $350. If you were resouceful, you could do this with junkyard parts for say $500-600. I suspect the rest of the fuel delivery path is more restrictive than any larger carburetor or throttle body you might consider, so I'd expect little or no payoff beyond those simple changes.

How about increasing the displacement? This is an old, thick cast iron block, and can probably go 100 over to 3.225" without sleeves. I recall there are 80-over pistons available off the shelf, maybe 100 over too. 100 over is (3.225/3.125)^2 for 6.5% increase, or 143 cid. Go 150 over and that's a 10% increase to 147 cid. 200 over is 20% to 161 cid. Typically power gains go in proportion to the displacement, and I'd think you could sleeve the block and buy custom pistons for under $1000. To me, that seems like the easiest path to a significant boost in power. Combine that with some increase in compression, smoother induction and exhaust, and you'd probably be up to that 20% mark. Is there a camshaft available? Likely you could have a cam ground for this application for under $500.

Once you ar in this realm, you'd want to put your engine on a dyno and see what you have, before and after. It could be a fun project, but hardly economical compared to the alternatives.

 

Chevy 4.3 or 350. The Buick engine are cool and are a jeep part and I like that, but are old and limited in that respect. A junkyard 4.3 with FI can be hd running for 600 bucks and much less on C/L. I understand wanting to keep stock, but after power brakes and power steering with a V6 and a 4 barrel.. I will never drive a stock jeep with Fhead ever again.

The fact is that fixing the stock stuff or trying to hop up the Fhead is just not economically worth it. I did all my modifications purely from a cost benefit basis. It was just cheaper for me to go v6 sm420 and disk brakes.

To do again I would go chevy 4.3 with FI and maybe an automatic too. Its just cheaper and more modern with better parts availability. I like nostalgic vehicles.. For other people to deal with.

 

The Buick is nice because the distributor is in the front, and you don't have to worry so much about firewall clearance. But it's true that the aftermarket support for the 4.3L is extensive compared to the Buicks.

There are lots of V6s from RWD passenger cars out there (ie Ford, Chrysler). The Chevy is dominant because the conversion is proven and well documented.

 

Yep. When I test drove my CJ 5 back in 69 with the 225 and optional 4.88 gears, it was quite an eye opener. It was an equally big eye opener when I installed the 327 in the 3B and every subsequent sbc has been an improvement as the displacement has grown. Suffice to say if I had the perfect restoration early CJ whatever, it wouldn't likely ever leave the garage and I'm not going to sacrifice the space for that. Almost all the people I know that espouse the virtues of either 134 have never spent any seat time behind the wheel of a well set up Jeep with a healthy V8. Never ceases to put a smile on my face firing up the 3B.

By orders of magnitude-------- And there isn't really any firewall issue with a small cap distributor and the short water pump. In fact, you can fit any of the sbc's using that combo.

 

As far as machining the head on a 134, when I did mine, I was layed off at the time, I had a a few spare heads laying around, and I wanted to push the limits, just to see how far I could go before I hit a water jacket. I had time to kill and nothing to lose.

There is an excessive amount of cast iron in those heads. I could have filled a small shoebox with the amount of filings I removed, and I never did hit a jacket. I had incredible increases on the flow bench numbers. If I would have combined those mods with a custom ground cam and/or fuel injection, who knows what kind of power it would have had.

They are fun experiment with, but pushing them hard really does mess with their longevity. The rings seem to be the first things to fail. There are just more logical answers to more power to fit a near-period correct 4-cyl engine than to put too much work into the 134 and keep it dependable. An iron duke or a pinto engine are great options without going the route of the old standby v6 or SBC. If you're almost happy with the 134, a more powerful 4-cyl might be the ticket.

 

Like a VW TDI?...

 

Exactly.

Or a Volvo.

 

As far a wall thickness of the F134, I have pictures (posted by ITLKSEZ) of a 134 that was bored 0.080 over where the piston failed and the rod went through the cylinder. The wall was about 1/8" thick, so it could be possible to go 0.100 over if pistons were available. The 0.080 over pistons are commonly available. Between milling the deck and the head, you can get the compression ratio up close the 10:1, if you dare. You need a big cam for this much compression.
As far as carburation, I have a manifold I am gathering pieces for that will have two British SU carbs, either 1 1/2" or 1 3/4", side by side on a log manifold that enters the side of the heavily modified F134 head.
I'll post up a build (or add to the one started by Ryan) as things progress. I am curious the see the power that can be made by the F134. I know I'll never forget the sound these make at 6500-7000 rpm.
I the end, a mild 225 Dauntless will be so much better for power than an F134 grenade!
-Donny

 

I can vouch for a worked, high-revving F-head. They sound amazing and pull hard. This racer has a balanced/blueprinted F-head with a Crane cam. It screamed, and the top-end power felt similar to a stock 225.

 

HAHAHAHAAHHA

 

Sort of gets back to the fact that you can make just about any engine platform perform. It's all about the $ spent versus the rewards. And of course, the longevity. That is if it is in something you actually plan to use on the road/trail.

I can see absolutely zero rewards for pushing limits on a 134 in anything other than class racing-where the tow truck is handy and most people have at least one replacement sitting in the trailer.

 

Beauty is in the eye of the beholder. It is, in fact, very rewarding. Anyone can make a powerful jeep by sticking a bigger engine in it, but that's not the question.

This thread is about exploring options to make the 134 produce more power. Some of us are sharing our past experiences so the OP can decide if he thinks it's worth it. Not everyone wants a v8.

There is definitely room to gain some noticeable HP without sacrificing dependability, just by increasing airflow and fuel delivery. Donny and I have mentioned the outer limits; there is a happy medium that won't stress the components and will give modest rewards.

 

I've had my share of V8s in Jeeps over the past 35 years, whether they be AMC 304 or 390, and plenty of small block Chevys, and even a couple 289 Fords. My favorite was a Buick 215, just because it was so light. The whole Jeep was just under 2000 lbs, and it performed fabulously. The Dauntless is my next favorite, because Kaiser put them in, and they sound so funky (plus, they just work so well in a small Jeep).
Like Ryan suggests, I want to build an F134 to near the limit for the sake of it. I have the opportunity to pick the carcasses of a couple retired race Jeeps, so why not? I don't expect anyone else to follow this route, though I'm not re-inventing the wheel. The guys over on the Florida west coast have been doing this for around 60 years, and over time, have come up with some wild innovations that have been applied to the F134, like roller rockers on the intake valves, 4bbl induction, and electronic ignitions ( these need to run underwater for part of the race!)
The original poster (60CJ5) has a really nice looking Jeep and is looking for a little more power. There is no cheap easy solution, but some head milling to raise compression, a good ignition, and maybe better carburation, and either gears or an overdrive would net some results that are noticable. Its still an antique tractor engine, so embrace the character it has.
-Donny