Big Block minimum wall thickness

[Mopars & Missiles]

Gents,

Looking for some VERY specific answers to this question:

What is the minimum wall thickness you would consider safe to build a 600 HP/ 600 TQ stroker engine?

Using a 400 block, stroking to 500 CID, What is considered the minimum on the major thrust side of cylinder walls?

Minimum between cylinders?

Minimum on minor thrust side?

Would love to hear from members that have experience with this, especially someone like IQ52.

Thanks

 

[lewtot184]

from my experience the thin spots are about 45 degrees to the left and right of the thrust sides. the cylinder is cast in an oval, not round. i'd keep these spots at .125 or greater.

 

[IQ52]

Minimums huh? 600/600 isn't to awful much. So I would look for, major thrust .200", pin sides .140", minor thrust .180". All this AFTER boring.

 

[Mopars & Missiles]

Minimums huh? 600/600 isn't to awful much. So I would look for, major thrust .200", pin sides .140", minor thrust .180". All this AFTER boring.

Perfect answer, exactly what I was looking for. Thank you! Have checked two STOCK bore blocks so far and the best one has about .120" on two holes major thrust side. These are being checked near the center of the bore, about 3" down in the bore.

Just a check on my thinkin' - major thrust would be 1,3,5,7 exhaust and 2,4,6,8 intake? Correct?

Thanks again.

 

[IQ52]

Whoops. The connecting rod always points towards the thrust face on the power stroke, so intake side 1, 3, 5, & 7, exhaust side 2, 4, 6, & 8.

 

[Mopars & Missiles]

Thanks guys, I think I'm dyslexic or something like that.

 

[Garys1969RR]

So from these amounts of .120" cyl wall thickness on the major thrust side prior to boring, it looks like you still need to keep looking for a block with thicker walled cyl bores? How hard are they to find? Just curious, as I have picked up 3- 400 blocks lately. One even has a forged steel crankshaft. Came out of a truck with a 4 speed. I know a guy in Wy has one he wants to get rid of cheap.

 

[IQ52]

We just went through eight 440 blocks to get the right thickness. Then again I have a 400/451 that we made and the first block we tested needed to have one cylinder offset bored .010" to get the major thrust wall thickness to .200". It went on to make 787 hp on pump gas.

 

[Mopars & Missiles]

....it looks like you still need to keep looking for a block with thicker walled cyl bores? How hard are they to find? Just curious, as I have picked up 3- 400 blocks lately. One even has a forged steel crankshaft. Came out of a truck with a 4 speed. I know a guy in Wy has one he wants to get rid of cheap.

Yep, I still need to find a good block to build. So, open to suggestions. Doesn't seem too feasible to drive clear across the country and back though for a good block. Must be a good one out there somewhere fairly close by? :eusa_think:

 

[Garys1969RR]

Thats awesome, IQ 52. Just got my 451 built and puttin it in my RR this weekend. Can you say what cyl heads you used on the 451/ 787 H P? Can well ported 906 or 915 heads flow well enough for that level of H P?

 

[Garys1969RR]

Don't know what I was thinking back then. But I now see that the major thrust side (to the left side of each cyl wall as viewed from front) has to have at least .200" thickness AFTER boring to withstand the high forces encountered when making 5-600 horsepower.

So from these amounts of .120" cyl wall thickness on the major thrust side prior to boring, it looks like you still need to keep looking for a block with thicker walled cyl bores? How hard are they to find? Just curious, as I have picked up 3- 400 blocks lately. One even has a forged steel crankshaft. Came out of a truck with a 4 speed. I know a guy in Wy has one he wants to get rid of cheap.