Topic: RPM's in 4th gear

[MakoML]

Well I thought I'd bump this thread with new information.   I just rebuilt the engine.  Its .020 over and 10/10 on the crank with quality bearings, pistons etc.  New stock cam and lifters.  Head surfaced and valve job.  New engine mounts, timing set, water pump, etc.   The cat was previously gutted,  I put a new OEM type muffler on it and am looking for a tail pipe to go on it.

It revs and pulls hard thru gears 1-3,  I can shift at 4500 RPM now.  But I still can't get it to pull over 3300 rpm in 4th gear on level ground.  Still have the 4.10's and 33's.   

I think I am going to drop back to 31's soon, I can't think of any other issue other than lack of power to turn the 33's.

[jfrabat]

It revs and pulls hard thru gears 1-3,  I can shift at 4500 RPM now.  But I still can't get it to pull over 3300 rpm in 4th gear on level ground.  Still have the 4.10's and 33's.   

I think you answered your own problem...  4.10 and 33's is not the best combo.  I run 4.88 and 33's, and I am STILL not happy with it.  4.88 and 31's are a great combo, so 5.13 should be the right gering for 33's (which, of course, means D44 axles, and I cannot afford that with new ARB lockers and all).

[dwtaylorpdx]

I found its not just tire height its tire width.
When I dropped from 33x12" to 32x9" my mileage went up over 4 MPG...
In headwinds its even better.


Dave