OK so Colvin lists CJI as the 350HP 402 w/TH400 but the CTW as the 350HP 402 w/TH400 High Perf which begs the question - what's the diff?ggtsvnv said:Mine is a CJI block 402 CID (L34 350 H/P) turbo 400 & is a two bolt main. There are no documented L-78 (375 H/P 402 CID) Turbo 400 Camaro SS's. So I don't think it was an L-78 Camaro block. So unless the CTW block was used in Chevelle SS's with the L-78 with an auto trans (which I don't believe was true;due to all solid lifter engines getting 4speeds to my knowledge) then I would have to think that perhaps the block was machined for 4 bolt mains. I know a small block can be machined for 4 bolt mains, and would think that a big block could be also. Unless by some chance some L-34's were 4 bolt blocks from the factory.
From inception through '67 396 cranks are all forged steel. From '68 forward the low HP units receive cast iron. Of course what GM define as low HP and what we define as low HP are not necessarily the same. So you have a variety of cranks that could have been installed (Casting numbers):deputyrob said:All L34's were forged crank, 10.25 comp and high lift hydraulic cam. from 65 to 70. but in 65, 66, 67 they used Holley carbs and went to Rochesters in 68. Dunno why the book says on is high perf and one not.
flowjoe said:OK so Colvin lists CJI as the 350HP 402 w/TH400 but the CTW as the 350HP 402 w/TH400 High Perf which begs the question - what's the diff?
HP & TQ don't change (an L-34 is an L-34) so heads, pistons, intake and carb will all be the same leaving the block and crank to be different. Colvin shows the 3969854 block to be in use for both L-78 & L-34 in '70. There are a lot of different crank numbers so who knows.
Surely GM didn't create a separate suffix code for no reason.
FWIW, I can see some L-34's leaving the factory as 4 bolts just cause (like some L-48s are 4 bolt and some are 2 bolt)same block, same line.