401, 0.40 Over Pistons

[Wagoneer Taylor]

I am looking for a set of 401 Pistons, at .040 over bore.

I have a set of 401 Pistons at 0.30 over bore for sale or trade.

[email protected] or PM me, thanks.

[Carnuck]

Did you check for core shift?

[Wagoneer Taylor]

How would I do this?

[Carnuck]

Machine shop can do a sonic test to see. Anything over 0.020 bore it pretty much requires it or overly hot spots cause the block to warp and crush the cylinders as someone else found out the hard way.

[Wagoneer Taylor]

Oh then yes I will be having them check this.

[J20 project]

EEk, everything I ever heard was that about .30 over was the most you want to do in terms of being able to cool the engine...But...in all fairness, I have never done it.


J20

[Wagoneer Taylor]

I keep getting stories either way, lots of people say you shouldn't go over 0.020 (I don't disagree with this, there appears to be a lot of info to support it). But on the other hand I get a lot of people saying they have gone to 0.030 all the way to 0.060 without problems.

I'm going to take every precaution I can with this block, it was already 0.030 over and had no signs of over heating or running hot that I could find. It still had all the little disks that a rebuild shop puts on it and the engine was rebuilt in 2001.

I realize that all of you guys are just trying to look out for me and the engine but I'm gonna risk.

[rang-a-stang]

I'm at 030 over without issues. During my build I searched theamcforum about boring and there were lots of posts from folks with 401 blocks that were 040 and 060 without issue. There was also lots of advice to "not go more 030" but I only saw one person at 060 say they had heating issues. There were other seasoned AMC V8 engine builders saying it's not a big deal to go 040 or 060. It would probably be best to have the walls sonic checked to check their thickness but if 030 is fine, I can't imagine an extra 010 would make so much of a difference that you would have problems.

[babywag]

You might try a PM to SC/397 maybe he has something you could use?
He is an AMC engine guru.

[Wagoneer Taylor]

I talked to him as well, he said I should be fine. At 0.060 over you will want to sonic check for sure. He also mentioned one of the most important things is to clean out all the water jackets of crud.

I plan on sonic checking anyway.

[SC/397]

https://www.ebay.com/itm/Eutectic-AMC-Jeep-401-Dish-Coated-Skirt-Pistons-Set-8-040-14-silicone/151059601112?hash=item232bda96d8:g:X-AAAOSwualcWE8C

Here are some 0.045" over.

https://www.ebay.com/itm/Wiseco-Piston-Kit-PTS541A45-Pro-Tru-Street-4-210-Bore-Flat-Top-for-AMC-401/282840895921?epid=27017007821&hash=item41daa191b1:m:mPiTIgA4AhPykOUulucYcmg

[Wagoneer Taylor]

https://www.ebay.com/itm/Eutectic-AM...AAAOSwualcWE8C
Here are some 0.045" over.
https://www.ebay.com/itm/Wiseco-Pist...hPykOUulucYcmg

Thanks!!!
Have you used the Eutectic pistons before? Ive never heard of them.

[SC/397]

Those listed in the add are forged not Hypereutectic.
But to answer your question NO, I do not use Hypereutectic pistons. They will not take any detonation whatsoever. In my humble opinion, normal old cast pistons are better than hypers.

[Wagoneer Taylor]

I just read the post a bit more carefully

Thanks again