midyearvette

anyone out there know why the 66 big blocks changed casting numbers by sept. of 65?.......numbers went from a 961 to a 942 and the latter was used in 2 or 4 bolt form. i could never figure this out. i actually read years ago that the 961 was actually a bored 962 396 block from 65, but have never really had a reliable source on the subject.....

Nitrodamus

I'm relying on a foggy memory, but I think the 1965 early 396 blocks had very thick cylinder walls that could easily be bored to 427. I'm thinking the new cast numbers were for the new non-bored 427.

Also, the later 396 blocks could not be safely bored to 427... the walls were too thin.

Nitrodamus

There is an old story that has been around for years concerning the 427 Corvette.

Who knows if it is true or not.

GM had a in-house rule that certain cars could not exceed 400 cubic inches. Supposedly Duntov convinced Chevrolet upper management that the heavy 396 engine was causing handling problems in the Corvette. He said the car needed to be lighter in the front. He explained that easiest and least expensive way to lighten the car and fix the problem was to bore the engine... to 427.

midyearvette

that zora...he always had a way to sell it to them!!...........

geopar

The only part of the equation I can answer is this:

All 962 blocks were 4 bolt.

All 961 blocks were 2 bolt.

So, the 961 could not have been a bored 962.

942, 351, 321, 439, 270, and 512 were cast both 2 and 4 bolt.

midyearvette

speaking of zora, rumor has it he actually talked mitchell out of the split for 64

rahaul

My understanding of the '63 split is Mitchell wanted it, Zora didn't, and

Nader axed it for '64 (safety guru nader).

jim lockwood

True.

Not true. Ralphie didn't have a voice as early as '64. People didn't start paying attention to him until around '65/'66 when his book, "Unsafe at Any Speed" was published.

I hate that book. The '64 Corvair for which I paid $1200 instantly became worth $200 because of it.

Jim

redred65cpe

According to the Muscle Car show I just watched Mitchell wanted it (he designed the car that way) and Zora didn't like it. Mitchell got it for one year. Nader was never mentioned. However, if both Zora and Bill both liked it, then I'd bet it would've been around for at least a few more years.

larry

Viking427

Search the archives, plenty of info there to put this rumor to rest. Yup, someone snuck one in on Noland's survey of 66's - probably why this topic surfaces every few months since his C2 book was published.
3855961 = 2-bolt only 396cid thin-wall casting. Chevrolet 325hp & 360hp applications.

uncle427

Over the years I have picked up and moved a lot of blocks, that 961 was always MUCH MUCH heavier than all the rest, including the 962.

I seem to remember 2 and 4 bolt versions, this would be long before people started to convert them for any type of "resto" purposes.

I know the cylinder walls were VERY thick and learned to not even blink at the thought of immediatly punching it out .125" and still have plenty of meat. I do not remember how much thicker the walls were but it was easy to stick a couple of fingers thru a cooling passage hole and the inner cylinder wall and one could very easilly feel how much thicker the walls were when a std 427 block was next to it for comparison, once you did that one time, ya just did not have to do it again with a 427 block next to it, it was that different.

Interesting story about Zora, although I suspect its just Lore, I would suspect it had more to do with bean counters finding out not that much cast iron and nickel was needed.
Anyway, best block in BB version GM ever made in my opinion!

uncle427

Ah, pickin on Ralphie again, I for one appreciate the efforts he made to ban teak wheels so if I were to wreck my car bad enough to cause my steering wheel to get wrapped around my arms that I would not have to worry about getting SLIVERS! And lets not forget we no longer needed to worry about being blinded by the sun by shiney wiper arms and blade holders after 65, they were always a problem during the rain!

oldskydog

I have never seen a 961 that would pass the pencil test. Pop a side freeze plug and try to insert a pencil between the cylinders. If it won't go through then it's thick enough for a 427 bore. If the pencil passes between them it is not thick enough for 427. I'm fairly certain that if they made any early 961's for 427 use, they would have to use a 427 inner core.
If in doubt, get it sonic tested.

PAmotorman

only 1965 425 HP 396 corvette blocks 962 can be bored to 4.250 no other 396 can be bored that far. also the way the lifters were oiled was changed in 1966

rayvaflav

Have you ever driven a '63 coupe and tried to use the rearview mirror ? It's pretty useless to see the traffic behind you but terrific to see the major styling cue of your car just by looking in the mirror ! After all, who gets to see the outside of their car while driving it (no need for the Alfa Romeo Periscopo owners to chime in here).