402 BB number Questions - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jimmi · 04-01-2007, 08:17 PM

Hey all Have a 1971 3/4 ton and I want to find out what year my engine is. I believe it is a 1971 402 as thats what I was told. I have some numbers off the pass side deck right under the pass side head but on the block. The numbers read T1223TKB can some one help decode this or get me in the right direction? Thanks Jim

72armyswbtruck · 04-01-2007, 08:47 PM

Try this web site
http://www.mortec.com/castnum.htm

72armyswbtruck · 04-01-2007, 08:48 PM

Sorry that one was for small blocks
try this one for Big Blocks
http://www.mortec.com/bbc.htm

JimKshortstep4x4 · 04-02-2007, 09:23 AM

According to the suffix code (TKB) the engine is a L-47, 402 truck engine used in 1971 and 1972 trucks. It was used in the 10,20, and 30 series in 71 but in 72 it was only used in the 10 and 20 series. It was rated at 310 hp. If you have the block date code you can verify the year for sure.

Jim

04-01-2007, 08:17 PM	#1
Jimmi Registered User Join Date: Mar 2007 Location: Arizona Posts: 13	402 BB number Questions Hey all Have a 1971 3/4 ton and I want to find out what year my engine is. I believe it is a 1971 402 as thats what I was told. I have some numbers off the pass side deck right under the pass side head but on the block. The numbers read T1223TKB can some one help decode this or get me in the right direction? Thanks Jim

04-01-2007, 08:47 PM	#2
72armyswbtruck Registered User Join Date: Feb 2004 Location: Idaho Posts: 4,034	Re: 402 BB number Questions Try this web site http://www.mortec.com/castnum.htm __________________ "Remember, They can Kill You, but they can't eat You, That's against the law!!!!!!!!!"

04-01-2007, 08:48 PM	#3
72armyswbtruck Registered User Join Date: Feb 2004 Location: Idaho Posts: 4,034	Re: 402 BB number Questions Sorry that one was for small blocks try this one for Big Blocks http://www.mortec.com/bbc.htm __________________ "Remember, They can Kill You, but they can't eat You, That's against the law!!!!!!!!!"

04-02-2007, 09:23 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: 402 BB number Questions According to the suffix code (TKB) the engine is a L-47, 402 truck engine used in 1971 and 1972 trucks. It was used in the 10,20, and 30 series in 71 but in 72 it was only used in the 10 and 20 series. It was rated at 310 hp. If you have the block date code you can verify the year for sure. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 04-02-2007 at 09:24 AM. Reason: spelling



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