Chevy Engine codes and such....
 

Wanted to see what some of you have made of the somewhat "cryptic" nature of the 350 Small Block casting #'s and date codes..

I am getting ready to re-power my 69' Step and needed all of the pertinent info for possible trade-in for core. Here are some #'s I pulled off of the block and heads:

Block Casting # - 3970010 (Date code is: D281)

Head Casting # - 3973487 (Date code is: D281..strange?)

Both date codes appear to be April 28, 1971 based on specs that I have found at various sites and publications. I have also seen varying information that says this could be either a 307, 327, or 350.....anyone have any reliable sources for information on this?

What has me wondering is something as simple as spark plugs.....I picked up some new plugs based on the 71' theory to replace the Autolite "145" plugs that were previously installed(not by me..), and they don't fit. Autolites application specs don't even mention compatibility with any 71' 350's...


Any info or links would be greatly appreciated.

=Slider

Re: Chevy Engine codes and such....
 

I pulled this from www.mortec.com

Block
3970010....302.....69....4...Z-28 Camaro
3970010....327.....69....2...Trucks and industrial
3970010....350...69-80...2 or 4

Heads
3973487....71-72...350..........1.94/1.5 or 2.02/1.6 valves, was also used on '71 350/330hp LT1, 75cc chamber

Re: Chevy Engine codes and such....
 

Thanks for the response...

That's what I'm getting as well....any way to tell which one it is? Even the date code isn't helping due to the fact that multiple engine sizes were produced within that range....

Aaaaaaargh!

Re: Chevy Engine codes and such....
 

If the pad codes on the right front of the engine block are legible, the suffix code will give you more information.

JIm

Re: Chevy Engine codes and such....
 

It is a 350. I have never seen or heard of a 327 using that block casting, and you do not have a 302.

Re: Chevy Engine codes and such....
 

The suffix is "TBC", if that helps...

Re: Chevy Engine codes and such....
 

Found this for you:

TBC 1970 350 convfwd cabs, a/t 255 4 C-10 to 3500
TBC 1970 350 m/t, 3 spd 255 4 K-10 & 20
TBC 1979 350 conv. cab, m/t,fed L LS9 165 4 C-10 to 2500

Looks like it's a 350, but I still don't understand why those plugs you bought wouldn't fit??

Re: Chevy Engine codes and such....
 

Thanks for all the replies and info. It indeed appears to be a 71' 350 w/ heads from the same date code. As for the plugs...that is another adventure.

I've located a new crate 350 that I'm going to drop in. Depending on the shape of the block when I pull 'er out, I may choose to rebuild, or, offer it up as a core. Next step will be to locate a lower geared rear-end so that I can take it on the freeway and not turn 5K at cruising speed....