Hi, I’ve noticed the 69 iron intake is designed differently than say a 74. The rusty one is the earlier one. Is there a performance benefit in the earlier intake ?

And yes I know about the performance benefits of aluminum. just curious about the iron intakes.

 

If you take a moment to study those two photos, you'll note that the only real difference is that on the early intake the runners from the RH side of the carb are on top and on the later intake it's the runners from the LH side that are on top. I suspect that this was done to make room for the EGR valve and associated passages. Otherwise the runner size and shape appear to be close, though there do appear to be some narrower runner sections in the later manifold just before the transition to the heads.

 

the early intake does have a larger port cross section . It’s slighter bigger after the runner T section, but much bigger before the T section between the carb and T split

you can see it by eye.. measure with callipers , it’s quite a bit.

the early one also doesn’t have the two EGR bungs protruding up into the plenum..that kills flow.

 

Is bigger better in this case? Sounds like it is. Remember Nick's Garage comparing the early intake and it having bigger runners than a regular Performer intake.

 

the OP asked if there was a performance advantage, and there is between those two.

if someone was looking for a low rpm higher TQ mileage intake for a 350, then the later one would be best. an even better factory intake for low speed TQ/mileage would be the 307 A5 small runner intake

 

I'd take 60's over 70's

 

Or the SP2P, if you can find one. The one you sold me worked great, impressive low end torque, especially part throttle.