340 ID help please

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LXguy

LXguy

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Hello:

I'm confused.

Is a 71 340 orange or blue?

If the block cast date is 6-71, is it a 71 or a 72 engine?

Anyone have a pic of the correct air cleaner for a '71?

Allpar says: "1970-71 engines were painted orange; they changed to blue in 1972-73, although some late 1971 engines ended up blue also." Sigh.

Thanks for any help!

Steve
 
crapshoot, IIRC around March/april the change over started to occur.
 
about 99.9% that engine was in a 72 which means it was a Blue, 8.5 cr, small valve 1.88 340, they switched the assembly line at the beginning of august for the 72 models. to know for sure you need the date off the front of the block
 
Now I'm confused....LXguy says it's a 6-71 block. Wouldn't that have gone in a late 71 build?
 
Usually there was at least 30 to 60 days from cast to assembly. For example my demon block has casting date of 7/1/70 was assembled 11/70 and did not go into the car till 4/2/71. since it was assembled 11/70 its orange but went into the car when most were getting blue engines. Not much set in stone with Chrysler! Did they misplace a rack of 340 engines? there is 4 months between the casting of the block and when it was assembled, then another 4 months and two weeks until it went into the demon.
 

Attachments

The change over to blue was around april 71. It would use the same air cleaner as the 70.
 
EL5DEMON340 said:
about 99.9% that engine was in a 72 which means it was a Blue, 8.5 cr, small valve 1.88 340, they switched the assembly line at the beginning of august for the 72 models. to know for sure you need the date off the front of the block
Click to expand...
The change was early in April and blue does not mean its a low perf engine. It will be a big valve 10.2 or so cr engine.
 
right the 71 spec blue engines were still 2.02's and 10.2to 1, but any 72 duster /demon cuda etc.. was low perf compared to the 71 and earlier. So the OP 6/71 block was most certainly a blue engine because it was cast two months after 340's were leaving the showroom floors with blue engines , i also have a 1/22/71 340 warranty block that is blue but not sure of the build date
 

OK, the code under the head on the front of the block is:

HM340R3681098

Does that mean anything to anyone?

Thanks,

Steve
 
H= 1972 Production model year
M= Mound road engine assembly plant
340= cubic inch
R= Regular fuel (low CR)
3861= August 26th 1971 assembly date
098 = build sequence 98th engine built (you may be missing a digit on the sequence)
 
does the cast of 6/71 have an actual day like 6/20/71 for example? all 340's i have seen have the 5 digit cast.
 
It's all pretty much been covered. But yeah, cast in June of '71 means it was assembled just after the line was changed to '72 models. If it was a forged crank (and I'd expect it was) than I'm inclined to say it would have had the taller pistons too. The heads could be 2.02 or 1.88s, and it would have been blue.
Like was said, you could never tell with Chrysler.
 
The full date on the block is 6-17-71

It is a forged crank.

How do you decode the VIN pad on the passenger side?

Is there some indication of which body it came in?

Mine's first two digits are 2B, does that mean it came in a '72 B-body?

Thanks,

Steve
 
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