Max overbore capacity on '71/'72 360's ?

[OZCHARGA]

Curious as to what the max overbore capacity is on early 360 blocks. For my next engine project I am weighing up the pros/cons of building a mondo cube street/strip stroker with the new MP cast 4" arm crank !

I have 2 early std bore 360 blocks - one of which has been sonic tested and shows min of 0.180 on the thrust side of the block. In OZ, all the 360 engines we received were J/915 headed/ 1.88 valved 71/72 blocks - so we were relatively lucky in this dept. I have been told that these early 360's were all cast from 340moulds/cores, hence the thick cyl walls.

My questions are:

i. How much can these early blocks be
bored SAFELY?
ii. What is the MINIMUM usable cylinder
thickness that should remain after
boring?
iii. Has anyone successfully bored these
engines to 4.080 or 4.100 and used
them in a street/strip application?
iv. What problems could arise - ring
sealing, overheating, cylinder wall
flexing etc ?

If this can be done successfully, then I'll be looking at a 4.100" bore x 4.00" stroke =
422 cubes OR 4.080 bore x 4.00" stroke =417 cubes. Torque monster on the street !! Any info would be great, sorry for long post!!

[CudaBoy]

Hi, I read article from Mopar Muscle -magazine. Tico Racing says, that 4.100 bore
is safe, if you can use '71-72 360 blocks
because these are based on early 340 blocks.

But in my opinion you should stay at 4.060.
http://www.paalupaikka.com/cuda.html

[BillyBob]

OZ,
If needed, I have a new set of .060 pistons & rings(TRW) for sale.

------------------
BB
"Land of the free, home of the Mopar"
98 Ram SLT Intense Blue V10 4X4

[OZCHARGA]

BillyBob, are these pistons suitable for a 4" arm crank? Won't they stick out of the top of the bore? If these slugs are forged TRW's, what do they weigh inc pins ? How much are u asking for the pistons/pins?
Thanks mate !

[BillyBob]

OZ,
The TRW part number is L2405F 60
You will have to check with someone more familiar with weights & applications as to whether or not they will work for your motor.

------------------
BB
"Land of the free, home of the Mopar"
98 Ram SLT Intense Blue V10 4X4

[vsteel]

You will need special pistons for the 4" crank, the stock pistons will come out of the top of the block. I was told that keith black had some. When I called the engineers were still designing them, they said they should be out in the fall sometime.

I then decided to call mopar, they said that the crank came out before they were ready with pistons. I called them in mid may, they said that pistons (hyperutectic) should be out in aug. (give or take) But they did verify that nobody makes pistons for this crank. Your only option is to get a custom set made at this time, or you can wait.

[Joecuda]

You all have no ingenuity! I am doing the same setup, and am only going 4.04 because I haven't yet been able to locate an early block. If the casting is ....496 it can go for sure to 4.100, but check with sonic test for irregularites. The mopar SB book says that any block up to about 76 can go to 4.100 though, but I would be very careful here, because it exactly says that it can "go out more because of 340 water jacket size," and we all know that 340 goes to 4.100, but the problem is that the casting does not change for that year, which makes me think that 496 might be the only sure shot. As far as pistons, (what I meant by above) is that all you have to use is Chebby pistons, as they are (a) cheap, (b) come in all different sizes and cc's and (c) will fit. Now, I have just been calculating cc's with gaskets, heads, stroke, bore, cc of dish in piston, compression height of piston and with a little ingenuity, I have found a few setups in which you can get chebby 350 pistons hyperte..whatever from Federal Mogul with special anit friction coat for about $230!! All you have to do is have bushings put in the rods to fit the pin! Now, given, rod ratio isn't the greatest (ideal of 1.8) but it is better then some stock motors! Good Luck. Keep in touch, as I know a few guys who between the group of us we are building our own types of SB strokers. Later. Joecuda