What is the difference between a 1970 L34 block that is stamped CTW compared to one stamped CTX? It is my understanding that CTX is manual trans, so it would have a Z-bar fitting on the side of the block for the clutch. Does the CTW also have this accomidation?

Thanks,
Keith

Originally posted by ratbldr:
It is my understanding that CTX is manual trans, so it would have a Z-bar fitting on the side of the block for the clutch. Does the CTW also have this accomidation?

Thanks,
Keith Yes,all the older Mark IV blocks will have that provision.

All older BB have the threads there for that ball stud, or does it have to be machined? How about the crank and that overworked pilot bushing; are all the 396 cranks the same as far as the pilot bushing? What would I expect to encounter in putting a CTW block into a 4 speed car? Any surprises?

Thanks,
Keith

Do all A Body BB Chevelle Frames have the Z-Bar fitting regardless of whether they are auto or manual cars?

The "z-bar" is a separate part between the frame and the block that fits on one end on a ball-stud that is bolted into the block, and on the other end, a slip-fit onto a stud that is on the frame. I'm assuming all the frames have a place to mount the side that slip-fits against the frame, but my question is on the machining of the block, and why it would be CTX in the first place. I'm sure there is enough steel on the pad to accept a tap of that area for the ball-stud, but are the CTW blocks tapped? Do they have a threaded area that is ready for the ball stud to be bolted onto the block? If both the CTX and CTW blocks are the same (both threaded for the ball-stud), then why did GM stamp them to distinguish between a manual trans and an auto?

Thanks,
Keith

Keith,

The CTW or CTX indicates the configuration of the complete engine as it is shipped from Tonowanda to the assembly plants. Both engines would have identical blocks. Both engines would be machined to accept a ball stud. The difference is that the pilot bushing, flywheel, clutch, bellhousing, and clutch fork would already be installed on the CTX engine. The CTW engine would have a flexplate installed. The engines would also have different distributors and carburetors.

Frames in automatic cars usually have to have a bracket welded or bolted in for the z-bar if you want to convert it to manual transmission. If you installed the CTW engine in a manual transmission car you would need to install a pilot bushing and a stud for the clutch z-bar.

Thanks, you've really helped me out! I have a 70 that is documented to the extent that I have all the dealer reciepts from all the oil changes and the 3 clutches the car went through in the first 42,000 miles, as well as the build sheet, protecto-plate and the transfer of warranty to the second owner. I'm the 4th owner. The origional trans is in it, with all the numbers on it. I bought it in a bucket and it was only missing the engine. My build date for the engine, according to the imprint on the protecto-plate is 10-06-69, mine being a CTX. To my dismay I have found a CTW block with a build date of 9-30-69fd, and I feel as though I have found God! I know now, with the help of you guys that the block is right for my car, so thanks again Team Chevelle!!

Keith

CORRECTION: The CTW block is T0930CTW and my protecto-plate is T1006CTX The casting date of the CTW block is I 28 9 with the pad stamped T0929CTX - this seems correct for my car with a build sheet production date of 10-11-69. Correct me if I'm mistaken. Seems like the block I found and the block that was origionally with my car and lost were probably sitting next to eachother in Tonowanda. -Keith

my W and X were mixed up on the last post. Does this sound right?

CORRECTION: The CTW block is T0930CTW and my protecto-plate is T1006CTX The casting date of the CTW block is I 28 9 with the pad stamped T0929CTW - this seems correct for my car with a build sheet production date of 10-11-69. Correct me if I'm mistaken. Seems like the block I found and the block that was origionally with my car and lost were probably sitting next to eachother in Tonowanda. -Keith

ps X + W = T1006CTX (algebra joke)

The two different CTW stampings (T0929CTW and T0930CTW) has me confused; I thought you had only one CTW block. But, yes, the CTW block with a I289 casting date would be only a week earlier than the original T1006CTX block. So it would make make a great replacement even though it won't make your car a numbers matching car. It gets you about as close as you could get without the original engine.

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The two different CTW stampings (T0929CTW and T0930CTW)

Sorry for the error, I picked up the block today and it was T0930CTW on the pad. The engine has the origional bore, +.030, which is a displacement of 402, so it's never been punched. I was not sure what to expect on the location of the date code (because the assembly date was prior to 1970), but it was near the casting number on the back, not on the side. One thing I didn't expect was to not find the last 6 of the vin stamped anywhere other than on the front pad. The vin info was located stamped above the oil filter area, in the grainy area of the side of the block vertically. Is this where it's supposed to be?

Thanks,
Keith