date codes

I have been told that the latest casting dates on 440 - 6 blocks were around 5-70 . were all the six pack engines built in two runs ? [70-71] [ excld-a12's ] if you wanted to put correct date coded exh. manifolds on a car built later than may , would they have a date when the engine was built or would they be closer to the build date ? I know things were all over the place ... does anyone have any photos of a 71 with the block and exh. manifold dates ??

There are no 440 sixpack blocks, just 440 blocks.

A sixpack engine is typically marked HP2

Casting dates can be all over the place.

HP2 designation as "typical" for 6 pack engines is a myth as far as I am aware........HP designates an HP engine assembled on first shift....HP2 indicates second shift assembly. I can think of no valid reason to only assemble 6 pack engines on 2nd shift. I assume these engines were assembled throughout the work day regardless of 4 barrel or 6 pack configuration. However, I may be proven wrong. It would not be the first time.

For the OP.....accepted date range for exhaust manifolds is several months to just a few days prior to the vehicle SPD. I don't think you will correlate it very well to block casting dates as they do not seem to align with SPD's.

I thought six pack blocks only got six pack rods until 1972 when they started using up the supply. So if that is the case, then wouldn't there be a way to differentiate between regular HP blocks and six pack blocks?

Correct, I have three ‘70 F440 HP blocks that all happen to be out of real V -code cars. One from a ‘70 RR Lynch Rd, one from a ‘70 cuda Hamtramck (my cars numbers block) and one from a ‘70 Super Bee Lynch Rd. All are HP and not HP2.

The “six pack”/HD rods were used in all ‘70-1 440-4 HP and 6bbl engines. The only differences were the valve relief pistons and 3-bolt cams being used in the multicarb versions. Both the 4 and 6 bbl rotating assemblies were externally balanced.

I get it that normal range on the manifolds are 2-3 months ...I know there are no 6 pack blocks. hp or hp 2 does not matter .. that being said , for the people who have real 6 pack cars [ or photos ], with orig. blocks , what is the latest known casting date seen on a 6 pack block ? if they are all over the place , there must be an early and a latest known date ? I am talking what is known here. and , what are the dates on those known manifolds . fwiw, I have never seen a six pack block with a casted date past 5-70 If that's the case , then you would be able to look at the latest known six pack cars and look at the cast dates . the reason why is I hear they built most of the engines in two runs .I have no facts . it is just a little more info on how things were done . any takers ??

The reason I used the 'typically" is that ALL 5 of my Sixpack engines are stamped HP2. Statically that seems off, but obviously possible.

Well you can forget that 5/70 date. The original motor to my 71 Challenger R/T 440 SIXPACK with a SPD of 3/31/71 has a casting date of 7/21/70 - over 8 months prior to the cars build date. However 71 dates have a far larger gap then 70 dates IMO.

what are the dates on the manifolds?

That I don't know. The car was made into a race car and restored back to stock. The car had headers on it when I got it.