Jeep Strokers

The billet cams are very expensive, i think i paid around $600 for a round lobe blank without a gear. Then it had to be copper plated, roughed down, heat treated, then finished ground. I think it cost about $1,100 by the time i was done. Without a gear you need to use an external oil pump, an race engines you would drive it from the front of the cam. For a street car, you would belt drive it from the crank. Many engine control systems can use a coil on plug setup, so you don't need a distributor.

One problem the jeep engine has is that the cam only has 4 bearings. Using a tube with lobes pressed on to it would not be rigid enough.

Getting to Alex comment about 500hp 300cid motors. These motors produce this power at 7000-8000 rpm. If this is what you are l0ooking for, then fine. I think what most people are looking for is the most power they can get bleow 5,500 or 6,000 rpm. a torque monster. Right the torque peak on a stock motor is probably aroound 4,000 rpm. if the engine would breathe better the torque could be maintained up into the 5,000 rpm rannge. The torque drops off because the engine cannot get enough air. SO if we make a 5.0L or even a 5.1L the air starvation problem will get worse.

Alex22 wrote: SilverXJ, I saw that you mentioned the pressed on lobe design for a cam in another thread. That would be a good solution to 2 problems at the same time. The one problem that I can see with that cam design is that the pressed lobe camshafts that are used in the ford modular engines (4.6 and 5.4) have been known to shift while the engine is running. I am not sure what caused the cams to shift, forced induction, stiffer springs or maybe just a bad batch. Maybe this cam style is worth some more investigation.

Yes, I was actually staring at a Ford V8 we pulled out of a van when I thought of that (what a nightmare that was... stupid van). I think a few other OEMs use that style of cam as well. I think the Jeep 4.7L V8 is the same way.

Plechtan wrote: One problem the jeep engine has is that the cam only has 4 bearings. Using a tube with lobes pressed on to it would not be rigid enough.

When you say not rigid enough, it it not rigid enough over all, or just into the cam harmonic speed?
If the tube isn't rigid enough over all, what about just a bar? i.e. not a hollow tube. Are there even any aftermarket companies that do that or is it just an OEM thing?

I think this is a little off topic, but, we can discuss it a little more. you want a cam that is a rigid as possible so when you put in larger springs, or go to higher RPMs the cam will not flex. All valvetrains will have harmonics, it is just where they are and how severe they are. I do not know the ideal size for a cam core diameter, or exactly how much force is applied to it. What i do know is that people spend allot of money on things like roller rockers and hardened pushrods to try and make the valvetrain more robust. The stock setup is probably ok for a mild preformance setup, but high lift rates, strong springs and high rpm will put much larger forces on the cam.

The straighter the port, the more port area(aka CFM) you can get away with, with out killing performance. Do to slow air speed in the port. (aka fuel falling out of the air/fuel mix.)

I love this statement, because it is so true. "Just because you made a bigger HOLE. Does NOT mean more HP will fall out of it."

I real like the LS-1 LS-6 idea a lot..................but i think modifying the intake Port, aka raising the roof is a good.......NO! Make that a GRATE idea.

No matter which way you go it's going to require a lot of work. Keeping your present head, and valve train that you Payed good money to buy as well as set up.

Guys, this set up will not only, allow a much higher cfm, that Pletchtan NEEDS(sorry for got you name ) but will also allow a much better flowing head that can make more power and torque down low(shaping the port for low rpm) then we will EVER get out of any head produce so far Period!!!!

Just my 2 cents

Flash wrote: I love this statement, because it is so true. "Just because you made a bigger HOLE. Does NOT mean more HP will fall out of it."

There's another good quote from an old timer, "A trash can will flow a lot of air."

Pete,
In your first post you made mention of welding two ford heads together. As we've discussed, they'll be alum. A cylinder head as we all know, has to be a strong and rigid unit. Im not a welding EXPERT by any means, but when welding two heads together, you inherently create a weakness were the weld meets the parent material. This happens no matter what material you use but if you are using cast style head blanks you will be compounding this weakness. I know for a fact the best cast alum to weld is 356, the lower numbers such as 312 are too porus and dont contain the proper addatives for strength. Are forged units available? Post-weld re-heat treatment would be a must as it would bring the weld and parent material to the same "T" heat treatment. Im not sure what the aftermarket uses for heads but keep in mind that, with the exception of 3 alloys, ALL 2xxx and 7xxx series alluminium are not weldable. Most pistons are made of 2xxx grade alloys and 99.9% of all alum connecting rods are either 7075-T356 or a proprietary derivitive. Food for thought.
Cheers,
Will

Flash wrote: I real like the LS-1 LS-6 idea a lot..................but i think modifying the intake Port, aka raising the roof is a good.......NO! Make that a GRATE idea.

Does any one have a CAD drawing of the 7120 or 0331 heads? I think it would be a huge undertaking but its totally plausable to section the head insert .375" and reblend the ports. Ive totally had this talk with pete in person. I think its the best way to fix the head flow prob but also the most expensive (really).

what about a set of v6 vortec heads? would these line up any better? i know they flow pretty good.

tigerShark wrote:what about a set of v6 vortec heads? would these line up any better? i know they flow pretty good.

Cylinder bore spacing is 4.400" on a 4.3l and 4.375" on a ford small block.

Hmm, I'll have to go measure the RB head I have sitting here. Lots of other stuff has to line up though, right? Head bolt holes, water passages, oil passages, probably some other stuff I'm not thinking about. Maybe it's been covered and I should read over the whole thread, but what are you guys planning to do about all of that? I can poke around at some of the Japanese I6 heads I've got and are at my buddy's shop.

a 24-valve OHC head would be tricky. Someone over on NAXJA is in the process of a 2JZ TT in conversion in his XJ(the Aisin-Warner autos in the supra and XJ are very similar).

So what are some imported I6 engines that might provide a head for the jeep engine?

The only big six that comes to mind is the Jaguar 4.2 - not sure what the bore spacing is, but not a bad place to start. Double over head cams, hemi heads.

What about the Jag V12 engine? It started out at 5.3 liters with a 3.5" bore. By 1991 it had been expanded to 7.4 liters in the XJR12

Who else produced BIG V12 engines? Mercedes and BMW?

What about the Pontiac OHC Six from 1966 to 1969? Think it was a variation of the Chevrolet inline 6?

Just trying to think a little out of the box.

Are there any large 4 cylinder engines that might offer heads?

look at this one-off 292 chevy head, the thing is welded from v8 heads and looks pretty smart

http://www.customdesignperformance.com/ ... _head.html

bmw has a 3.0l straight 6 but i don't know anything about it

On the BMW i-6 heads, the intake is on the driver's side and the exhaust is on the passenger side. DOHC, 24v, VANOS(PIA)