High performance manifold differences
On the left is a 70s 340 drivers' manifold, you can see the ribs on the far left. you can also see how the 60s 340 (on the right) rises higher:
Here you can see the 70s 340 (ribs) and how it is designed so that it's further away from the block compared to the 60s 340 (left).
The ribs are very obvious on the 70s 340:
Yes, I've had a few..........
treblig
From all the 340 manifolds that I've had (I've had over 100) every one had a 2 1/4" outlet EXCEPT in the 70s (71 and up I think) passenger's side had a 1 7/8" outlet. The 60s 340 driver's side had a different design that made it rise a little higher over the plugs and it also hugged the block a little more. The 60s 340 driver also DID NOT have the extra ribbing like in the 70s. The 70s 340 driver's side didn't rise as high and also moved away from the engine block (just a little). That's why (if you have manual steering) you can use the 60s driver's side 340 manifold on the early As.
On the left is a 70s 340 drivers' manifold, you can see the ribs on the far left. you can also see how the 60s 340 (on the right) rises higher:
Here you can see the 70s 340 (ribs) and how it is designed so that it's further away from the block compared to the 60s 340 (left).
The ribs are very obvious on the 70s 340:
Yes, I've had a few..........
treblig