Max RPM of Jeep Engine

[1bolt]

If you use a factory cam, maybe... I read that sentence to mean the factory cam is thicker between the lobes. There are no lobes in an engine block so that's the only way I can read it.

[Plechtan]

I guess we need to find sombody with a 99 up motor who can take some measurements and compare them with a pre 99 block.

[dwg86]

I have a 2001 block tore down on an engine stand. What measurements do you need?

[Plechtan]

The width of the Cam support bosses, the things the cam bearings are pressed into, a picture would probably be good too. We can then comapare the measurmaents and photo to a pre 99 block.

[dwg86]

I could only measure the front one today. It measured .901. I need to bring my Vernier caliper home from work tomorrow to measue the rest. I will also post some pics.

[Alex22]

If you use a factory cam, maybe... I read that sentence to mean the factory cam is thicker between the lobes. There are no lobes in an engine block so that's the only way I can read it.

X2
If you want to get a stronger cam you need 99+ cam core, not sure who makes them, or a stock cam that can be reground without grinding through the hardened layer.

dwg- can you measure the camshaft diameter between the lobes?

~Alex

[dwg86]

Yes I can. I will post later tonight. I don't get hom from work until 8PM.
I have a new cam coming from Engle. I can measure that when it arrives. Hopefully it will arrive today.

[dwg86]

OK, I measured the stock cam between the lobes, 90 deg. from the casting line. I got 1.32 inch. The block casting where the cam bearing are pressed in measured .799 inch. As soon as I get my Engle cam I will measure the lobes and the diameter of the cam between the lobes, should be sometime this week.

[Cheromaniac]

The 4.0L blocks of all ages have the same 4 cam bearings with the same dimensions so even the newer blocks/cams aren't immune from the 5600rpm harmonic. The problem is caused by the cam being supported by only 4 bearings. A gear drive prevents timing chain breakage but doesn't prevent the distributor from being spat out of the block. The only way to solve the problem completely is to redesign the block. Maybe Hesco's new aluminium block (if it ever goes into production) will have extra support for the cam.

[Plechtan]

"I see" said the blind man.

I went and found a picture of a 4.0 cam, I does look pretty weak, Maybe a billet blank would help. My motor will not be running a distributor or oil pump off the cam, so that should reduce the load, and a timing belt should help control the harmonics. I guess the only way to find out is to try it.

[Mgardiner1]

Thats the spirit!

How about changing to a harness that uses coil packs? that doesn't use a distributor, correct? Not saying the distributor CAUSES harmonics, but it certianly can't help

[SilverXJ]

The harness that uses the distributor packs uses a sensor where the distributor use to be which also drives the oil pump. You would also need to take the PCM from the same vehicle and you would also need the gauge cluster if you wanted to run factory gauges.

Whata re you going to do for an oil pump if not ran off the distributor? Also, where did you find a timing belt for the 4.0? This should be a very interesting build.

[Mgardiner1]

Lets start looking for a 12 volt electric oil pump!!!

[Alex22]

Lets start looking for a 12 volt electric oil pump!!!

If you want to eliminate the standard distributor drive oil pump then go for a dry sump pump and run it off of the front pulley.

I had looked into making a belt drive system work on my engine but tossed the idea because for my application it wouldn't be worth the money or time for research and machining parts.

~Alex

[dwg86]

Got the Engle cam today. It has narrow lobes. I will post some pics with measurements when I get a chance...and a new battery for my camera.