78 360 block boring limits???

[71dart666]

How far can a 78 360 block be bored over? I have heard that the 76 and older blocks are the best and can be bored over the most. However I hear the newer ones (77 and newer) can only go .020 or .030 over. Any truth to this? Anybody have any experience with this or imformation?

[Relixracer]

you really need a sonic check to determine how far you can safely go. Ma Mopar quality varied from day to day in the late 70's, add in core shift and no one knows what you've got for sure without a test. Got my'76 block tested after boring .030 (which is really too late) but then I could put it together knowing my wall thickness.

Get it done after hot tanking but before you buy pistons then you'll know how far you CAN go.

My test was $40-- cheap insurance and peace of mind when building an engine.

[451Mopar]

I think my 360 is either a '76 or '77 year and it is 0.040" over because it did not clean up at 0.030".
On the otherhand, this is just a rv engine that only makes around 300 HP.

[6 packin]

You should be alright at .030 over. also .040-.060 needs to be sonic checked. I would bore it .030 over and let it fly!

[Billydelrio]

.030 should be no problem at all. I have sonic checked several 360 blocks and have not found one that would not take a .060 over bore yet. However, yours could be the first!

Billy

[345Dart]

Couple of different articles I have read say 75 and newer 360s go 030 max. 75 and older used same coring as 340 block and can go .060 over. Why go 30 if 20 will do the job. The more meat you leave in the block the better (and a possible rebore if something goes amiss).

[dwc43]

All of the 360 blocks setting in the shop for my race engines have been checked. Every one will go .060 over if I need them too. Most are .030 right now and ready to be built.
.030 is a safe bet,but if you go more have them checked for sure. It could save you some money.

[gotcha]

The best piece of advice listed in this post is "why go .040 when .020 will do the job." Save it for the next overbore.

* .030 on all 360's

* .040 on most 360's

* .060 possible on 71-76

* .080 possible on 71-73's 340 water jacket blocks. .(040 plus .040.)

I have seen a 71 360 block bored to 4.125

Sonic testing is the proper method. Now, if you square deck the 360 first and then bore them (the proper method) you will have trouble cleaning them up at .030, as the decks are seldom 90 degrees to the mains from the factory and you will be boring at a slightly different angle.

[451Mopar]

I picked up a 360 from a junk yard for $50, just because I needed the crank for my 360 RV build-up.
I found out the $50 360 engine is a 1971 year casting, but has already been bored 0.040" and has some rust in the cylinders because it was out in the open with out anything covering the the carb opening. Everyone seems to think these will go 0.060" over? I just hope it cleans up at this size as I may build a stroker with it in the future.

[71dart666]

Thanks for the input, I might get a 78 360 for a trade on my parts car. He said theres some surface rust in the cylinders and it would need a rebuild but im told its an original bore. And all id really need to do is go .030 over since most pistons that are sold are usually .030 or .060 over. My eventual plan is a high output stroker engine pushing over 500 hp, hopefully the block would be sound enough to take it.