'66BB engine numbers

[Classicvette63]

I'm trying to find out exactly what engine is in my step-dads '66BB for him. I know it's not the original 427, but other than that I am lost. I did notice that the pad is blank. The #'s I did get are: driver's side, rear of block: 3999289 alittle farther up are the letters "conv" and even farhter up is "CM9T"

On the pass. side at the rear i could see: 820 followed by 73

Any ideas as to what engine this? Thanks for the help, Classic

 

[IH2LOSE]

from the book cars and parts magazine catalog of chevy V8 engine casting numbers 1955-93 page # 22
casting # 3999289 = 454-72 corvette 270 hp-72-75 chevelle-72-76 passenger-73-79 truck



Your other numbers are date codes I think (CM9T)and some one may be able to tell what they are from this is the only info I could atain at this time

 

[67HEAVEN]

I'm trying to find out exactly what engine is in my step-dads '66BB for him. I know it's not the original 427, but other than that I am lost. I did notice that the pad is blank. The #'s I did get are: driver's side, rear of block: 3999289 alittle farther up are the letters "conv" and even farhter up is "CM9T"

On the pass. side at the rear i could see: 820 followed by 73

Any ideas as to what engine this? Thanks for the help, Classic

Lemme see if I can be some help.

3999289 1972 454 270 hp 2 bolt

 

[Classicvette63]

Wow, is he going to be p!ssed! I was there when the restorer told him it was a period correct 427 that was very similar to an L-88 clone. I wonder if that is why he had so much trouble with engine. The mechanic thinking it was a 427 might have been using the wrong parts? Thanks, Classic

 

[IH2LOSE]

Thanks 67 where did you aquire that information from?


Just testing some smilies with may son
;stupid

 

[impala]

Hello Son of IH2LOSE,

This one is our favorite and we're testing too.

Eugene and Sons




:eek

 

[ChuckG]

On the passengers side, I would guess that the 8-20-73 is the casting date of the block, August 20, 1973. Chuck

 

[midyear]

Wow, is he going to be p!ssed! I was there when the restorer told him it was a period correct 427 that was very similar to an L-88 clone. I wonder if that is why he had so much trouble with engine. The mechanic thinking it was a 427 might have been using the wrong parts? Thanks, Classic

Just cause it has a 454 block doesn't mean its not a 427. you can take a 454 block, insert a 396 or 427 crank, use 427 pistons and you have a 427. orig engine could have had a bad block and the engine was rebuilt as a 427 using a 454 block, all 427 parts could then be used and it could be called a "period correct 427". check the harmonic balancer to see if its an internal (396/427) or external (454/502) balanced engine.

 

[Classicvette63]

What is the diameter of a 427 piston? He still has the pistons from the rebuild. How do I tell if the engine is externally balanced? What would I be looking for? Thanks, Classic

 

[midyear]

I beleive 427 bore is 4.25". here is a pic of two balancers, left is an internal balanced engine, right is a 454 external balancer. see the counterweight on bottom inside of the 454 external balancer. you can see/find this when balancer is installed. hope this helps.

 

[67HEAVEN]

Good work Dennis. Like they say, a picture is worth a thousand words.