400 Sonic Test Results

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slimjim

slimjim

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Ok, I’ve been trying to find some sort of guidance regarding cylinder wall thickness. Unfortunately, there’s so much clutter regarding the subject that it’s hard to pinpoint exact figures. I’ve read that .160 is required for anything over 500hp. Then I dug into another article and read that the .160 is only critical on the main thrust side. I’ve currently got the block in the shop waiting for direction. Block needs a .02 overbore to clean up. What do you think?

Block is a ‘71 230 casting with the thick mains (Aka the Cold Weather Block)

*Plan is to build a 500-600hp stroker*

3FB6A8DC-9DD6-45DA-9D2C-4DBDAE10DF9C.jpeg
 
Not to bad, not super great, it’ll take a good overbore. Half fill a/hard block of your going to build a beast.
 
I plan to keep this on the street for 95% of the time. Really don’t want to use hard block due to the high CA temps.

The shop recommended .02 over but, I’d like to go 0.032 over for a 4.375 bore. This is the first block I’ve sonic tested
 
slimjim said:
I plan to keep this on the street for 95% of the time. Really don’t want to use hard block due to the high CA temps.

The shop recommended .02 over but, I’d like to go 0.032 over for a 4.375 bore. This is the first block I’ve sonic tested
Click to expand...


The difference in the .020 and .032 overbore is .006 per side. If you can’t get .006 more out of an overbore, you are going too big to begin with.

IOW’s, if it will go .020 and be safe, an .032 overbore is fine.
 
MOPAROFFICIAL said:
More is better but 120 or better is what most find acceptable...and if you expect 200+ you'll be searching a while.
Click to expand...
Good point. At what point is it safely thin at?
For street?
For strip?

I have 2 more 340 blocks to sonic check before I make a move on a stroker for the track.
 
Isn't the thrust surface on the left side block toward the valley, or is the labeling transposed?
 
yellow rose said:
The difference in the .020 and .032 overbore is .006 per side. If you can’t get .006 more out of an overbore, you are going too big to begin with.

IOW’s, if it will go .020 and be safe, an .032 overbore is fine.
Click to expand...

You know, I completely spaced and didn’t think about splitting the .03 overbore in half to reflect the actual amount removed. I feel a lot better about the 0.32 overbore. Thanks

what would be a definite “too thin” measurement? Anything less than .100?
 
slimjim said:
You know, I completely spaced and didn’t think about splitting the .03 overbore in half to reflect the actual amount removed. I feel a lot better about the 0.32 overbore. Anything less than .100?
Click to expand...
Stock build block for that.lol
Yes many forget
...its a circle, split the #
 
famous bob said:
drivers side/toward the valley, pass side/go in same direction -to the outside of the block.
Click to expand...

I’ll have to ask the shop if there’s a mistake with the labeling. They labeled the above measurements as “Thrust” and “Minor” but, could have placed them in the wrong location.
 
I was going to say the results are in question based on how they are presented..
 
slimjim said:
Ok, I’ve been trying to find some sort of guidance regarding cylinder wall thickness. Unfortunately, there’s so much clutter regarding the subject that it’s hard to pinpoint exact figures. I’ve read that .160 is required for anything over 500hp. Then I dug into another article and read that the .160 is only critical on the main thrust side. I’ve currently got the block in the shop waiting for direction. Block needs a .02 overbore to clean up. What do you think?

Block is a ‘71 230 casting with the thick mains (Aka the Cold Weather Block)

*Plan is to build a 500-600hp stroker*

View attachment 1715600441
Click to expand...
That block will be okay. It isn't the greatest ever but it isn't the worst you could run into. Should be fine for a 600 hp engine. You can do the 0.020 bore now and then the block should last a long time since you'll be able to redo it one more time. If you take it to 4.375 now then it might be used up. Of course, it could take 50 years of driving before you used it up so maybe don't worry about it.
 
Contacted the machine shop and discovered the thrust side (drivers) was mislabeled. Driver’s side thrust leads towards the valley side.
 
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