Hi all.  Hope you had a nice new year.  I just bought a 1986 Chevy K1500 with a V-8 engine.  I know it is not original because the sticker says the truck came with a 4.3 V-6.  

The engine is painted black which appears to be the original color.  The pad in the front of the right head is squared off instead of long and rectangular like the older small blocks were.  The stamped code is V0124CLK.  There is no partial VIN number. When I checked this suffix "CLK"  there are about 4 choices.  One is for an early 400 the other three choices are for various years of 350 with a 1977 being the latest.

I looked at the back of the engine where the casting number usually is but could not find a readable number.  Instead it says "GM" below this there is a couple numbers I had trouble making out and what looks like "5.0"  which could mean it is a 305.

Were 1977 350s painted black from the factory?  When did Chevy switch the front area where the stampings are from the wide rectangular to the stubby square area?  

The carb does not have a working choke and it does not appear to be the proper one for the engine.  I am going to put a new one on but want to make sure I have it matched to the displacemtent of the engine rather than just throw one on there and hope it works.  

On the right side should be the casting number if it is in the 80's instead of the left side like the earlier small blocks 5.0 L.G means its a 305 c.i.but see if there are numbers on the right side of the block to be sure.If you can get those numbers and list them I can tell you what you have.  

Chevy didn't start painting factory engines black until the 80s, in the mid 70s they went to painting them all a light blue color.

The easy way to tell if it's a 400, look at the harmonic balancer. If there's a notch cut out of the back side of the circumference of the balancer, then you've got a 400.

It very well could be a 305, which would be preferred over the 4.3L V-6. What you might have to do to get the carb situation right, is to do some junkyard crawling and find an '80-'86 V-8 equipped truck and pirate the throttle linkages, kickdown cable, etc. to get your truck setup just right. Then just go to the parts store and buy a new/rebuilt Q-Jet for your '86, and it should hook-up just fine and will have a working choke.