.040 overbore...will it cause overheating in Bear

[Jeepadilly]

I am planning a build of a 360 for Bear and was thinking punching out the bore to .040...will this cause me a headache with overheating due to increased combustion heat???

[ July 18, 2003, 12:02 AM: Message edited by: Jeepadilly ]

[Booger]

I did a search on here for "360 bore" they say AMC says .045 is the max. I would say then that if AMC say that is the max that you won't have any problems over heating, but see what someone says who has already done this. Also are .040 parts really worth it?

[Marvin Gates]

Its so hot in Sun Valley, I would go with the minimal amount of over bore, or go ahead and do it and go with a aluminum radiator.

[ July 18, 2003, 01:02 AM: Message edited by: Marvin Gates ]

[Wesdog]

Make sure you can get the pistons you want to use as that may affect your decisions. Sleeving the block back to it's original bore is a good option also and may help with obtaining pistons depending on which ones you want to use. It will also help a little with cooling. There was a good thread on sleeving here recently and the work is being done in So Cal:

http://www.ifsja.org/ubb/ultimatebb....=020358#000009

Wesdog



[ July 18, 2003, 07:19 AM: Message edited by: Wesdog ]

[Hammer]

I run my stroker 360 block with .045" overbore. Runs fine, and with 9.8:1 compression as well.
The 360 blocks have a LOT of meat in them. The only point that is thinner is near the bottom of the walls where it meats the block. This is easily solved with some block hardener if you are worried, and it's cheap insurance anyway. Just don't use too much.
Btw, AMC says .040" as the max before it needs to be sonic tested. Not the max it can be overbored. Two different concepts.

[TomJ]

I run my stroker 360 block with .045" overbore. Runs fine, and with 9.8:1 compression as well.
The 360 blocks have a LOT of meat in them. The only point that is thinner is near the bottom of the walls where it meats the block. This is easily solved with some block hardener if you are worried, and it's cheap insurance anyway. Just don't use too much.
Btw, AMC says .040" as the max before it needs to be sonic tested. Not the max it can be overbored. Two different concepts.

What he said. Now the 401 is a different animal. DON'T go more than .030 over, no matter what. Been there, regretted that...

[tgreese]

Typical USA iron block motors can take two over-bores at 30 and 60. If you worry, have your shop do an ultrasonic measurement of the wall thickness in your block. That's a standard service for a reputable machine shop. Not free, but should be on the price list. If there is excessive core shift, I'd suggest you reject this block and find a better core. If this is a virgin block, it will almost certainly be ok.

Why 40? Did your shop measure the block and recommend 40? 30 and 60 are the standard for first and second rebuilds. If you go 30, you'll be reasonably sure to have another rebuild in that block without any sleeves ($$). The difference in displacement is negligible.

[MysticRob]

What he said. Now the 401 is a different animal. DON'T go more than .030 over, no matter what. Been there, regretted that...

Too late, this thread is from 2003. OP drilled it out, overheated, exploded the block, ran off a cliff in flames. You could've saved him if only you'd have posted this 19 years ago.

[backroadin']

You could've saved him if only you'd have posted this 19 years ago.

LMAO!!

[rang-a-stang]

Too late, this thread is from 2003. OP drilled it out, overheated, exploded the block, ran off a cliff in flames. You could've saved him if only you'd have posted this 19 years ago.

BWAHAHAHAHAHHAA!!!

Not laughing at you, TomJ, you are not wrong and we appreciate you posting up. I also went 030 on my 401 but was recommended to go 040. The cost difference in pistons was staggering. A set of 030 forged pistons was about $300 when I bought my, the 040 were over $1000!