determing engine block numbers

[tommys72]

i found the numbers on my block, they are V0121TDJ, i know the TDJ means it a 72 block, but how do i tie it into the vin to make sure its the original motor?

[truckster]

That number will only show the year (72) and application (truck 350/175 hp/ TH350/ 4-barrel). It's not going to match the VIN, because the block numbers weren't that specific.

[SS Tim]

Most seller's claims of "numbers matching" are full of something beside honesty. To know for sure would require a tear down inspection of a known documented engine. Anything less is a guess
from a very confident, expert informed external inspection to a WAG for ad copy.

Since GM did not VIN stamp these blocks you cannot say 100% this is it. However you can come close with the engine number. It tells us the plant build date and intended application of the engine.

So yours is:
V Flint engine plant
01 January
21 21st day of the month
TDJ conventional cab with auto trans. 175hp 4bbl carb.

Now the problem is TDJ was also used in 1980 in a similar 155 hp application. To verify yours is a '72 you would need to check the casting number and the casting date. These numbers will precede the build date but the range varies greatly. The other dated parts to check would be the heads, intake, carb, distributor and exhaust manifolds. These will all give you clues about how original an engine is or how bad someone wanted it to look original.

The little ray of sunshine here is the protecto plate has the engine number on it. This cross confirmation on top of the date on the blue door certification label gives a good firm date everything will precede.

Have fun!

[tommys72]

good info guys, thanks, im gonna investigate a little more. the old man i bought it from said it was original motor and trans, i dont doubt him at all...just seeing if i could get closer to actually verifying that. the block being a 72 is a good sign...with a 4 bbl and the TH350

[tommy69]

not for sure on the trucks but on gm cars there is another set of numbers stamped right below those that you listed that should be specific to the later part of the vin number if it is the original engine

[SS Tim]

Originally Posted by tommys72

...just seeing if i could get closer to actually verifying that. the block being a 72 is a good sign...with a 4 bbl and the TH350

Just remember the suffix codes were reused often several times. It is important to verify the casting number and date to be accurate. From your description it probably is the correct block. But could just as easily be a 1980 van short block that had be stuffed in there fifteen years ago, that is why we check if original or correct is a consideration.

The trans and carb. of course have no bearing on the block being original or not. In fact most carbs. I dare say are replacements that only application and date codes can confirm as correct.

[Duncan and son]

Jason "son" will hop on here and let us all know how to confirm if is in fact a correct original matching No. engine

[72 K20]

I have an engine number That I'd like to decode as well,, actually,, 4 of them. Would it be alright to post it here ?

Thank You ! Tom

[sameyrasmea72]

I agree with the above, There is no way to know 100% for sure if the block is the original block. If the VO121TDJ matches the protectoplate, then that is about as close as you can get. If the VO121TDJ matches the protectoplate, the only way it would not be original was if the engine came out of a similarly cofigured truck built on the same day and same plant.

[Duncan and son]

[QUOTE=72 K20;5724572]I have an engine number That I'd like to decode as well,, actually,, 4 of them. Would it be alright to post it here ?

Thank You ! Tom[/QUOTET
Tom, Jason is very good on numbers codes etc ( I always say he is smarter than a white rat) I am sure it is ok to ask questions and Jason and others will help you.

[72 K20]

Ok ! Here goes !

Big Block in my 72 C20 TO527CLB

Small block in 71 C20 parts truck VO403TDS

Small Block was told it was a 305 K1212 CDD

Small block supposedly from an 88 chevy van V0802 TWA

Any and all help is greatly appreciated !! Thank You ! Tom

[SS Tim]

Originally Posted by 72 K20

I have an engine number That I'd like to decode as well,, actually,, 4 of them. Would it be alright to post it here ?

Thank You ! Tom

Sure, this thread is about decoding and examples always help.

[SS Tim]

sameyrasmea72,Duncan and son, Thanks for hoping on this thread. You have opinions I trust and invite corrections or clarification of ambiguities.

[tommys72]

Originally Posted by 72 K20

I have an engine number That I'd like to decode as well,, actually,, 4 of them. Would it be alright to post it here ?

Thank You ! Tom

go ahead man

[tommys72]

Originally Posted by SS Tim

Just remember the suffix codes were reused often several times. It is important to verify the casting number and date to be accurate. From your description it probably is the correct block. But could just as easily be a 1980 van short block that had be stuffed in there fifteen years ago, that is why we check if original or correct is a consideration.

The trans and carb. of course have no bearing on the block being original or not. In fact most carbs. I dare say are replacements that only application and date codes can confirm as correct.

i know there is no bearing to those, it was good to know that nothing crazy like a 2 BBL came out lol...id love to have the protecto plate with the truck...that would be nice

[MusicMan70]

Another possible alternative may be the buildsheet...

I believe that the Buildsheet has a location for the block number as well. I have seen Buildsheets posted on this Forum with the corresponding number; unfortunately does not have it on there. I'm still confident it was original to the truck.

[SS Tim]

Originally Posted by 72 K20

Ok ! Here goes !

Big Block in my 72 C20 TO527CLB

Small block in 71 C20 parts truck VO403TDS

Small Block was told it was a 305 K1212 CDD

Small block supposedly from an 88 chevy van V0802 TWA

Any and all help is greatly appreciated !! Thank You ! Tom

Thanks Tom!
Now I see why you were asking. This what I have crossed through a couple of sources. To do anymore a casting number and date will be needed. In the case of the car line engines the VIN too.

TO527CLB Tonawanda May 27th CLB is a 71-72 car line LS3 engine code.


VO403TDS Flint April 03rd TD "S"? Are you sure???


K1212CDD St. Catherines, Ontario December 12th CDD is a 72-85 car line code used on 267, 305 and 350


V0802TWA Flint August 2nd TWA is a 74 C60/6000 350 160hp 2bbl

[bruceman1968]

Hey Tim, I have TDS listed as a 1980, c-10 truck, 350cid, 170 hp, manual trans, LS-9, 1x4, vin code L, and federal smog.

[SS Tim]

Originally Posted by MusicMan70

Another possible alternative may be the buildsheet...

I believe that the Buildsheet has a location for the block number as well. I have seen Buildsheets posted on this Forum with the corresponding number; unfortunately does not have it on there. I'm still confident it was original to the truck.

True... I should have mentioned that as well. Not sure but I think the engine suffix code is the same for most build sheets in box 11.

[SS Tim]

Originally Posted by bruceman1968

Hey Tim, I have TDS listed as a 1980, c-10 truck, 350cid, 170 hp, manual trans, LS-9, 1x4, vin code L, and federal smog.

YES, That seems to be the only application. Found it over in a camaro forum I haunt from time to time.

[SS Tim]

This will help get people started.

http://www.nastyz28.com/decode.php

[72 K20]

SSTim
Thank You for the results ! I'm pretty positive on the S in the TDS code and Bruceman1968 could be right,, the engine has a sticker on the valve cover from a local shop that has long been out of business suggesting that it is not original to the truck.

The K1212CDD is probably a 305,, it has an aluminum Q-jet intake and this seems right for one of the so called "high output 305 ". I will have to tear it down to see what it is. I know that the cam is flat on several lobes so it is ready for a rebuild whatever it is.

The TO527CLB is in my 72 C20,,the truck came with a 402 but I didn't think it was original to this truck. Either way,, it's a big block and will be coming out.

The K1212 CDD was pulled out of an 88 van and has TBI on it with the pan mounted dipstick.
This is the motor I wanted to build for the C20. I sure think that GM could have come up with a better code system.

Prime example The LS3,, 71 or 72 402,,,,, or the LS3 vortech. How about the LT-1 ?

If it warms up some I will try to get some casting numbers off of these small blocks to zero in on the year,, that will probably tell us what they are.

I thank you all for the information and discussion !! I will be looking forward to future postings in this thread !!!

Take care everyone !!!
Tom

[bruceman1968]

Tom, If you grab the date code and the casting number off the blocks, we can tell you exactly what those engines are without tearing them down.

[Duncan and son]

Hey Tim, you have some good info..you must have been taking your smart pills. Bruce excellent job explaining what is needed to identify an engine (picture is worth a 1000 words)

[bruceman1968]

Originally Posted by Duncan and son

Hey Tim, you have some good info..you must have been taking your smart pills. Bruce excellent job explaining what is needed to identify an engine (picture is worth a 1000 words)

Thanks, SS Tim is a numbers guru like your son. Tim has been very helpful to lot's of members questions and he is very gracious teaching me and others the art of gm numbers decoding. It's guys like you, Jason, and Tim that make this site such a great source of information.