401 overhaul ?

[mud89]

I decided finally to overhaul my poor rigs engines : a 401 from a Cherokee bought for parts for a J10 and my CJ’ 304, which both barely run. The post is mostly about the 401. Advices are welcome..
First I spent a part of the night to extract that thing from the Cherokee

On a stand with my CJ’ 304

[mud89]

Then I tried to estimate the 401 condition
I think that the Cylinders are not bad but the crank is worn and will need at least a grinding??
I’ll also ask a shop if there are any cracks
Cylinders
Cylinders ridges : 0.002’’/0.003’’
Cylinders out of round : 0.0005’’/0.001’’
Cylinders tapers : 0.001’’/0.002’’

[mud89]

Rods, rods journals and rods bearings
Rods side clearance (with a feeler gauge) : ok for rod journals 2 and 3, but 0.016’’ for rod journal 4 and 0.018’’ for rod journal 1 (front), which is the max according to the TSM specs
By the way Does someone know the OEM value for fillet radii ?

The wear of the rods’ upper bearings is uneven ?

Plastigage give a clearance between 0.003’’ and 0.004’’
I didn’t detect large tapers or out of rounds for the rods journals with my micrometer and I don’t have the tools to measure bent or twisted rods
For info , the numbers stamped on the rods #1 (648) and #8 (660) are different from the others : 685?

[mud89]

Crankshaft endplay and runout
The endplay is large, at the limit according to the TSM specs : 0.008’’
The measured width for the main bearing #3, between the flanges is : 1.2665’’?
It seems that the runout is negligible

[mud89]

Main journals and main bearings
Lower bearings are worn, upper bearings not too much except number one, I guess because of the belts for engine accessories
Plastigage give a clearance between 0.003’’ and 0.004’’ (more for the rear main)




Next step the cam

[Nutz-n-Bolts]

Great stuff! I'l be getting my CJ's 360 back some day from the shop, (to be my first motor build) so I'm going to watch and learn from you ! Love all the pictures.

[GentleRF]

That is a great write up. You seem to be detail oriented which is a very good thing when working on our beloved older Jeeps.

[mud89]

Yep I like engines and i want to learn about these AMC and their building, got already a few docs, it's going to be slow since i don't want to ruin them, not easy to find a 401, i cross my fingers..