Don Terrill’s Speed-Talk

Bob Hollinshead wrote: ↑Sat Feb 16, 2013 11:19 am From Jenkin's book The Chevrolet Racing Engine: page 8, for racing use it is valuable to select a block that is "hard". There is some variation in the production casting material, and we often use a portable Brinell tester to find "hard" blocks. Page 6. The best factory block casting to obtain is part number 3970016. This case has the thick main webs and 4-bolt caps for added crankshaft support.

BrazilianZ28Camaro wrote: ↑Fri Jun 03, 2016 5:27 pm A few years ago I was milling a set of SBC 283 #896 powerpac heads to install rocker arm studs. Despite the fact both heads had the same casting number from 67-68 ( If my memory is right), one was harder to mill than the other.

That was a pretty noticeable difference by the tool cutting sound, for those who are used to mill.

BLOCKMAN wrote: ↑Mon Dec 02, 2019 8:33 pm I sonic test every OEM GM block that goes through my shops and according the sonic velocity I don't see and difference in material make. Their usually high 1800's. The Chinese Dart look a like block I believe was around 1300 and PBM was calling those blocks High Density blocks, You can see where those went.

The 010 blocks have different webbing then the 010/020 blocks the 010/020 in most cases have the oil galley above the timing cover and the main webbing is better with those blocks.

BLOCKMAN wrote: ↑Mon Dec 23, 2019 8:57 am

trmnatr wrote: ↑Mon Dec 23, 2019 4:12 am

BLOCKMAN wrote: ↑Mon Dec 02, 2019 8:33 pm I sonic test every OEM GM block that goes through my shops and according the sonic velocity I don't see and difference in material make. Their usually high 1800's. The Chinese Dart look a like block I believe was around 1300 and PBM was calling those blocks High Density blocks, You can see where those went.

The 010 blocks have different webbing then the 010/020 blocks the 010/020 in most cases have the oil galley above the timing cover and the main webbing is better with those blocks.

Carl, I have an 010/020 marked 010 with heavier duty main webbing with"2482" nodular caps but does not have the tapped port in the front however the cylinder wall thickness was much thicker than a typical SBC block. My grandfather used to have a story on those 010/020 blocks, and he did work for GM & he did all engine, transmission and rear end rebuilds when GM dealers rebuilt them with the needed parts plus he did a lot of street race stuff along with drag race stuff. How true it was IDK but made sense. He stated the GM 010/020 block came in 1969 302 and 1970 LT1 due to the nodular caps, thicker main webbing and had a higher nickel so it was in these applications because both engines were available in cars as a "race package" with an off road camshaft etc and the short blocks were identical from the production street cars to off road ordered cars. Makes sense, although not saying its true. I have seen the same block with DZ on the deck and it was also an 010/020. Also every 010/020 with 2482 main caps has always been more of a silver-ish color, so who knows wtf they did Lol

I don't see any difference in material make up between the 010 blocks over the 010/020 blocks, As stated the 010/020 do have a better main webbing and the cylinder thickness seems to be the same with both blocks, The older blocks seem to fail more sonic tests over the late 880 blocks, Now we have a lot better tooling then 40 years ago.

pdq67 wrote: ↑Mon Dec 23, 2019 11:27 am I haven't read this whole thread, BUT do want to ask what cast-iron alloy were the old Cad V-8 blocks made out of?

I ask because I seem to recall that they could have over 100,000 miles on them and not have much, if any ridge??

This tells me that Cad blocks were harder than our beloved SBC's.

The motor now has its cylinders cast in a block...