Red line value for the 4.2L CJ7 engine

4500 rpm.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's

William Oliveri wrote:

And it's gonna be out of breath way before it gets there. (Let's hear it for AMC!)

No way....

Mine will pull out to 55 mph at 4500 rpm in 2nd gear easily.

Don't know where 3rd tops out at, but it is 'way' up there. 85 mph in

4th is only 2700 rpm on mine.

I am running the stock BBD carb, an Accel SuperCoil and a straight exhaust with a dynomax super turbo muffler.

All manually set up, I killed the computer.

The computer acts like a governor and clamps down on the timing advance so they run out of steam way before 4000 rpm, closer to 3500 and it hits 'the wall'.

Mike

j carter wrote:

Mike, are you using the stock Tach or an aftermarket version? I was thinking about buying a new Autometer Tach in my area but the guy selling it says that he seems to red line at a little over 3k. He has the same setup as me, 4.2L engine with the Mopar MPI kit installed. I don't want to buy this tach if I can't get a proper reading.

Thanks,

Bill

I have the Laredo package with the stock tach and clock.

My tach also matches my tune up tach right on, so it is accurate.

Mike

William Oliveri wrote:

Ya, but guys, guys, this is in '4TH' gear!!!

I do have 5th gear!

And I did just check it this morning on a highway run out to pick up a cheque. I had the spedo pinned at 85 and I was just hitting 2700 rpm in

4th.

I have 'tons' of pedal left, it isn't anywhere near the floor at 85 in

4th. I guess I should have dropped it into 5th just to see how low it revs.

My speedometer is also calibrated right on according to my GPS unit.

Mike

breyfogle wrote:

I can believe that.....

I have a stock engine '79 with 33" tires, 4.10 axles and a T150 3 speed and that runs out of steam about 4200 flat out which works out to just over 100. I tested this early one morning doing a 60 mile journey 'at pace' (first 5 narrow British lanes, next 55 motorway (freeway)). I did the 60 miles in a shade under 40 mins making a 90+ mph average.....pretty much what you expect for a 100 mph top speed. I cannot of course condone speeding and all applicable laws are for your own safety and should be adhered to!

Not sure how long the engine or tranny would last doing that all the time though! Certainly a bit cruel doing it to a 25 year old block! Just needed to know!

Paul