"X" on the block
- Thread starter Bobaloo
- Start date
From my reading and correct me if I'm wrong, but the X wasn't for determining if the block was for a truck or service vehicle. It was used for the assembly line production to mark special order engines. You'll find X marked 656 blocks without the cilinder wall notches. The notches themselves are the sure way to determine if the block was for "truck" use. They were to decompress the engine and have a unshrouding effect on the exhaust valve, creating more torque.
cheers
cheers
rarerodder
Active Member
348 X
I have a 348 with block number 3857655. According to the Mortec number list it is a 62-65 truck block. It also has the X on the front of the block under the left head. It does not have the compression reduction notches. What is the benefit to have this X block?
I have a 348 with block number 3857655. According to the Mortec number list it is a 62-65 truck block. It also has the X on the front of the block under the left head. It does not have the compression reduction notches. What is the benefit to have this X block?
rarerodder
Active Member
Great news!
This is great news!
Cause now I can tell all those non W-Block guys that my X mean 'eXperimental' engine. I can tell stories like this was the prototype motor that was considered for use in the Corvette. 
: Or better yet-the upcoming lunar rover. :eek: I can tell a different story to everyone who asks. 
no1: :takethat Ok, I'll tell them truth-it don't mean nuthin. Oh well, the intrique was fun while it lasted.
:
This is great news!
Cause now I can tell all those non W-Block guys that my X mean 'eXperimental' engine. I can tell stories like this was the prototype motor that was considered for use in the Corvette. : Or better yet-the upcoming lunar rover. :eek: I can tell a different story to everyone who asks. no1: :takethat Ok, I'll tell them truth-it don't mean nuthin. Oh well, the intrique was fun while it lasted.:
Another version is that X indicated the part was cast with a new mold, as the 58 283 engines and heads all had the X. The 58 heads were the first to have accessory mounting bosses on the ends and the block was first to have side mounting bosses, both of which required a new mold.
63409
Well Known Member
Is there a difference between an 068 block without an X compard to one that has an X.Maybe the 068 block with an X is more like a 814 block where there is a difference in cylinder wall casting thickness and some other changes,also was the 068 block with the X casting cast after april of 1962.Ive heard that these 068 engines with the X casting are very expensive,why.
X marks the spot!
Aubrey, I have two of those "068" blocks, one dated March 24, 1961 and the other January 29, 1962 and neither one has an "X". To confirm what others have mentioned, all my other (newer) blocks (814s, 422s, 656s) have the "X". Doesn't seem to matter if they are QA/QB hiperf blocks or QD truck blocks, the later ones all seem to have the "X". The 348s I have are from 1960 and 1961 and do not have the "X". The one 348 I used to have (TomO now owns it
) that was from 1965 did have the "X" on it. So it seems that the later (newer) blocks perhaps all had this "X", whether it was a 409 or a 348???
Hope that adds some empirical evidence, if only from a small sample of 10 or so blocks.
Cheers,
TomK
Aubrey, I have two of those "068" blocks, one dated March 24, 1961 and the other January 29, 1962 and neither one has an "X". To confirm what others have mentioned, all my other (newer) blocks (814s, 422s, 656s) have the "X". Doesn't seem to matter if they are QA/QB hiperf blocks or QD truck blocks, the later ones all seem to have the "X". The 348s I have are from 1960 and 1961 and do not have the "X". The one 348 I used to have (TomO now owns it
) that was from 1965 did have the "X" on it. So it seems that the later (newer) blocks perhaps all had this "X", whether it was a 409 or a 348???Hope that adds some empirical evidence, if only from a small sample of 10 or so blocks
.Cheers,
TomK
63409
Well Known Member
Tom Kochtanek,and or Aubrey,one friend of mine who lives in san diego has a 62 Impala with a 409 068 block.the casting date is Jan of 62 at the rear of the block and the built date on the engine pad is late june 22 62.Also the block has no X casting in the front,is this correct
CDNpontiac409guy said:...see if my flathead V8 engine block has an.....
Oh man, the various cast letters and numbers on the Flatheads opens up a whole 'nuther bag of worms... Z, L, 99, etc, etc.
Just to keep it interesting, 61 409 blocks had X's on them. Mine was cast 11-15-60 as pictured. Tommy's (real61ss) block was cast in April 61, I believe, and it also has the X's cast under the top of the bellhousing mounting flange. These X's appear to have been welded onto the mold. This block was cast with the outer mold of the 011 348 block but the inner mold was changed for the thicker cylinder walls. If my theory is correct, then the X indicated the inner mold change on the 61 409. I believe the 068 block mold was not changed from the 61 so no X. The 814 block had casting changes to the outer mold so it has the X. I believe the 422 also had some casting changes but I'm not sure about the 656. The 655 348 block mold was changed from the 011 348 mold so it too would have the X. Can't prove the theory but does anyone have a better one?
Attachments
"I have two of those "068" blocks, one dated March 24, 1961"
Hmmmmmm, that's a month earlier than my '61 623 block was cast. Not to get off the subject of the X but I didn't realize they casting the "new" motors while they were still casting the "old" ones. Learn stuff everyday!!!
Hmmmmmm, that's a month earlier than my '61 623 block was cast. Not to get off the subject of the X but I didn't realize they casting the "new" motors while they were still casting the "old" ones. Learn stuff everyday!!!
My bad!
Tommy, my bad on that one! It was dated May 24, 1961, which comes after the make of your block. I think it was a pretty early "068" block destined for a 1962 vehicle. But it does have a very odd stamping on the front pad, not a "QA" or a "QB" as expected of a 1962 block. It has an "H" in it... Maybe it was pulled off the 62 line and dropped in a 1961???
Plans are to put forged pistons, a set of 1147 heads, and 3 two barrels on it and stuff it in my 1961 Bel Air Sport Coupe, which was originally a 348 car. Have one of those 1961 four speed T-10s (iron case, aluminum tail) that goes with it.
Sorry about the date mixup.
Cheers,
TomK
Tommy, my bad on that one! It was dated May 24, 1961, which comes after the make of your block. I think it was a pretty early "068" block destined for a 1962 vehicle. But it does have a very odd stamping on the front pad, not a "QA" or a "QB" as expected of a 1962 block. It has an "H" in it... Maybe it was pulled off the 62 line and dropped in a 1961???
Plans are to put forged pistons, a set of 1147 heads, and 3 two barrels on it and stuff it in my 1961 Bel Air Sport Coupe, which was originally a 348 car. Have one of those 1961 four speed T-10s (iron case, aluminum tail) that goes with it.
Sorry about the date mixup
.Cheers,
TomK
blown55409
Well Known Member
I have read that GM changed foundrys in 61 or 62 and that the X was put on there by the new foundry to denote their castings. Also the newer casting were suppose to have a higher tin content and thus a stronger casting. Can anyone verify this as I can't remember my source?
very best regards
Chip
very best regards
Chip