To date code a engine does the date on the engine have to be 6 months prior to build date or does it have to be only a month prior? I was wondering trying to find date coded engine for my 70 Duster 340 with a build date of March 24, 1970.

6 months ??? First off the IMPORTANT DATE is the ASSEMBLY DATE of the block. I haven't looked at 70 340 cars to see how close but I have seen many 69 big block B bodies and the assembly date of the engine has been within DAYS of the SPD , my 69 dart 383 GTS included , casting dates have been as close as a couple weeks before the assembly date thoug I have only seen as close as 3 weeks . My own personal 69 Bee has the assembly date of the original block one day AFTER the SPD of the car .

I'll stop there before some uptight numbers guys gets his PANTIES all in a bunch .

Post a pic of the assembly date and your cars SPD and we can see how close your block is.

More info

Here's where to look

I haven't found a block yet. I have some parts guy looking. I wanted to make sure before I bought anything.

Here's another block I have, I don't have a pic of the assembly number but It's probably somewhere around when your car was built.

the 340 in my challanger was cast in June 1969 for a vehicle SBD of Dec 1969. Assy date on the engine was late Nov 1969

a buddies 1968 Coroent R/T has it's original block also with an assy date of 1 day after the cars SBD

My 70 Challenger R/T vert has an engine assembly date the day after the scheduled production date as well...And a casting date two weeks prior...The rear axle pumpkin was also assembled the same day as the SPD & then the housing was assembled the next day...Sounds like lots of cars didn't follow the scheduled time table...

Ma Mopar had horrible inventory control which is one reason they were headed for Chapter 11 back in the 70's. It isn't unusual to find blocks with more than a year between casting date and assembly date. The typical spread is usually a few weeks but there is no "magic" time frame. It could be most anything on a Mopar. Remember, it wasn't built in a Toyota plant where things run on time, it was built by Chrysler.

This just keeps coming up over and over, doesn't it? Chrysler built cars to sell, not to restore. Inventory control? Bah! Find the part and make it work. There's a reason they almost went belly up back in the day.

R.

The sbp date of my car is 288721.

Where did you come up with that SPD? It should be a 3 digit code, post a pic of your fender tag and I'll help you on it.

Yeah I saw that Berry, it's that last number he posted that made me ask

Here's the pic of the fendertag.

is this ad not garnering the proper response ?

MAN! Have enough paint on that tag? Makes it a bit tough to read without a 10 minute photoshop endeavor. Anyway, it appears to have 324 on it so your initial March 24, 1970 seems to check out.