JERSEYJOE
Can a 401 be safely bored to .060? I know a guy that has a .060 401 with new in the box pistons. Says he runs them all the time with .060 and even more. I was under the assumption that .030 is fine and that .040 was max only after a sonic check assured a wall thickness of at least.100.
jeepsr4ever
Some can and some can go further. Many have gone to .080 over bore.
tufcj
Have it sonic checked before boring to .060, but I have seen a lot at .060 and even more.
Bob
tufcj
JERSEYJOE
What minimum thickness would make the machine go tilt?
fifesjeep
You could always have it sleeved.. but that'll cost some money and you'll still have cooling troubles if you don't drop the coin into a HP water pump, aluminum radiator etc etc..
jeepsr4ever
Jerseyjoe minimum would be .070" for trouble
73hornut
I'm running 60 over. Better cooling is needed.
1980_Cj7
Interesting. We finally gave a "new" machine shop the go ahead to clean up our cylinders from the scuffed pistons. We were already .030 over. I had read that AMC recommended a max over bore of .025.
We told the shop to take the minimum possible. They were talking about going to .040 over, but we are hoping the cylinders will clean up with just some honing, and keeping our fingers crossed. They were a tad tight to begin with, so that should help us now. The shop also mentioned sleeving if necessary.
In the short 300 miles we put on the engine after the first rebuild, it seemed like it wanted to run hot, even with a FlowCooler water pump, the heaviest duty (copper) radiator we could find, and a 2-speed Taurus electric fan. It was funny, it ran cooler in stop and go traffic around town than it did cruising down the Interstate.
MaxW
I'm Running 60 over with NO cooling mods as of yet. With no truoble. Got 200 miles on this 401. :?
ironman_gq
was your motor leaning out at cruise speed. i had one that would have no problem at idle and slow speed off-roading but would overheat at cruise. turned out my carb was gummed up and causing my motor to run lean and hot.
jeep_man_401
My 401 is 30 over and dynoed at 460 hp, I'm running the stock rad. (2core) and a aftermaket "high volume" alum. water pump without any problems. I did switch to a 165 stat from the 195 though. Stays cool in traffic and highway.
donwag
I had actully planned on a custom aluminium rad but the shop did not get it done in time. Had the stock rad cleaned out, put it on, runs fine.
Flowkooler water pump, 180 thermostat, and heavy duty fan clutch. And don't forget to use a fan shroud.
jeep_man_401
Damn...I knew I forgot something....:oops:
