Im calling BS to this " -1 is better than -8 (or even 15!)" hogwash. Id like to propose a theory that the suffix behind the 2780930-340-x is nothing more than a 4 based (?) casting cell number or casting position in the foundry, Not a core change or revision number. The sand cores were all identical, held to a precision that a sand casting could hold. They were not different from a -1 to a potential -16. If a casting core changed, so did its block casting number. Calling all 340 owners: post your block casting number, and 340-x suffix and date of manufacture. I bet we'll eventually get different suffix numbers on the same date of manufacturing and even low numbers cast days after high numbers *. Ill start with @5150DodgeBro pristine example of a very early 340 casting date, and then a few more from our own FABO site. 2780930-340-4 produced 6/22/67 2780930-340-3 produced 6/23/67 -----* BUSTED!!!!! ----- 2780930-340-3 produced 5/07/70 2780930-340-1 produced 1-18-71 2780930-340-7 produced 9/25/72 Lets see 'em!
2780930-340-8 with a production of 11/27/1969 I had heard about the different dash whatever’s being better but decided after fifty years you could have the “best dash” block and the “worst dash” block and the best block to rebuild may not be what all was claimed to be best, but the worst…. After 50 years the best dash block to have is one that runs LOL.
I don't know if it's right or wrong but read years ago that the number after the - was how many core boxes were changed. I don't remember when the count started, it's been years since I read it.
And did you guys know that pointer with the dots around it is the casting hour marker. Work shifts were 8 hours, so if the pointer was at the first dot from the 12:00 position that mold would have been made in the first production hour, pointed at the second pointer the mold would have been made in the second production hour and so forth. There should also be a second marker or pointer on the casting to indicate 1st, 2nd or 3 rd shift. Although some foundries used a screw whose head would form in the mold and show in the casting. A standard straight slotted screw for first shift and a Phillips head screw for second shift. The time between the mold being made and the iron being poured in is typically in the minutes. Molding lines where automotive blocks were cast would run at a rate of 80 to 100 molds to hour. Molding lines where cylinder heads were cast would run at rates of 200 molds per hour. Simple castings like flywheel housings and brake drums where there were no cores to be set could run at perhaps 300 molds per hour. The cast dates and shift markers were typically very accurate, as they were set once at the start of the shift. The hour markers were less accurate as to change the hour marker the molding machine had to be stopped, locked out, a person would go to the pattern and move the pointer, then the molding process re started. A good crew could do that in a minute, but those molding units were held to high standards for uptime and for most molding unit foreman, changing the pointer was not the top priority.
Have 2 340’s One in the car is a 69 block, don’t remember the date but the casting number is 2780930-340-2 Can’t find my mirror right now, and as we all know is a PITA to see with headers in the car... The other is 2780930-340-1 dated 1-14-71
Wow, didn't know a lot of this. I noticed on my block there was a pointer with D and N which I assumed was D for day and N for night
