I have 3 mopar 340 x - blocks in my back garage. one has never been used.
They are mopar racing blocks. I thought this was cool being as I never knew what was in the black plastic bags in the corner of my garage.
I’d be swaping one of those into the 240 thats for sure!
Uhm … X blocks?
All LA blocks are cast the same.
You probably have X head 340s.
But that’s a Mopar myth too. The X heads will totally be owned by a set of … ah damn, been too long … 904(?) casting - mid '80s swirl port lean-burn heads with oversized valves and the Mopar P&P plate treatment. They’ll even outflow the Edelbrock aluminums.
340s are nice, but I’ve always preferred the 318s to rev, and the 360s to make torque. Plus 340s are way too expensive. An econo 360 can be grabbed for $100.
And hellz yes, put one in a 240.
The LA series will make more power, pound for pound over a 302/305/307 or 350/351
Only 19-inches head to head … smaller than an SR. LAs are tall though, gonna need a cowl-hood.
o/t but I just noticed your photosloppy…
flip the rims vertically so the highlights and shadows match the rest of the pic heh
no I mean an mopar factory racing x-block. I have looked at all of them they have the x stamped in them…
Yeah … I think you’re confused.
The X designation is for the cylinder heads, not the block. 340s came with J heads, or X heads. The X heads were very good in the 70s, but have a much better reputation than they deserve. As I stated before, the swirl port lean burn Cop heads from the 80s will easily outflow them, and give a nice bump in compression.
There’s no such thing as a racing block. Mopar offers Magnum motors, but those are 360s and the blocks are the same original casting from 72 on.
But, there were only two different 340 blocks. The “other” block is the T/A block. The T/A blocks have thicker webbing for installing 4-bolt mains.
They stopped making the 340 in 1972. It ran from 1967- and there were only two blocks used (if you have 3 T/A blocks, which I’m sure you don’t, you’d be sitting on a nice retirement plan). They only sold 2,399 T/As, so the odds of 3 of those motors ending up in Canada are really, really really slim. And honestly, they’re no better, just desirable for collectors.
There were J heads with 1.88" valves to start, then the X heads with 2.02 valves, then the 360 J head, which was slightly revised, and also had 2.02 valves.
There’s only two casting numbers for the 340 blocks. Go on and check yours
2780930-340
3577130TA-340
On the other side of the block are the casting date/time/shift stamps.
It will appear like 3.15.69 or 3-15-69 and have a clock shape above it.
I was playing with Mopars while most of you were still struggling with the Dewey Decimal System
And for the record, there was no such thing as Mopar back then. It was called Direct Connection.