High Alt CPS.. question

[Blue88Comanche]

I sorta jumped the gun a little, I think i ordered the High Alt for the 2.5 4Cyl. instead of the one for the 4.0 6cyl.

 

the Part number for the part i ordered is 5300 5421

 

the part number for the 4.0 is 5300 3659

 

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edit:

 

the guy in the parts department said the part number changed, i bought it any way

[Eagle]

I believe the 2.5L and 4.0L use the same CPS.

[HOrnbrod]

The non-HI ALT CPS is the same p/n for the 2.5 and 4.0 engines. However, the HI ALT CPS's have different part numbers. What this shows me is that the HI ALT 2.5 CPS will work on the 4.0, but the amount of advanced timing is different. But I think the timing difference will be negligible and it will work just fine.

[jimoshel]

When I was a kid, Well,,,I was at one time,,one of the tricks we used to get that little extra was advance the timing and stretch the springs to get a earlier spark advance. My '38 Chevy running a 260 Jimmy called for 6 degrees at idle with 12 degrees at 3000RPM. Advancing the spark 1 1/2 degrees for every thousand feet in altitude came out to 14 degrees at idle and 20 degrees at 3K. Woe upon the guy driving down to the flatlands and forgot to retard the timing. With all the computer crap I wonder how many guys, and gals, even know how to set a set of points or check the timing any more. :wrench:

[HOrnbrod]

With all the computer crap I wonder how many guys, and gals, even know how to set a set of points or check the timing any more. :wrench:

 

Ain't that the truth. My olde timing light and feeler gauges have been gathering dust for many years. However the timing light comes in handy with the MJ as they had the good sense to retain the timing marks on the 4.0. Of course you can't adjust it though...........