Best Ford head for 347

[shelbydoug]

The AFR's show an intake flow of 296@.550". That is considerably better then stock Boss 302 or 351c heads at around 270. According to Mr. Gillis, the original GT40 heads are around 240.

What that means is you do not need to run a radical camshaft with those heads to make them breath well.


The "old" adage with aluminum heads is that you need to run a static compression ratio of 1.1:1 v iron heads to EQUAL the thermal output of the engines.

The issue here is that the compressability of the fuel remains the same and IF 10:1 was as much as you could run with pump premium then it will be the same with iron or aluminum heads. So in effect, you are giving away some power (torque) with aluminum v iron heads.


Will you make more HP with 296 cfm on the intakes? Probably but the increase of HP with the increase of air flow is not directly linear. Definitely in the 25 to 30 hp vacinity though.


With a 347 and correctly matched components you SHOULD be in the 500 hp ball park. Why Kiwi only showed 425 on West's dyno is a mystery to me?

Randy thought he knew why but never fully explained his rationale on the subject back then. I suspect though that it was the COBRA intake that was the limiting factor but other intakes were never run to compare the results?

[Shawn]

My choice may come down to what I find at Ford Carlisle.  What would be a good set of Ford iron heads to match up with a 289 block?  With the crescent shaped water passages on the 289 not present on modern heads (iron or aluminum )is this an issue?

[shelbydoug]

My choice may come down to what I find at Ford Carlisle.  What would be a good set of Ford iron heads to match up with a 289 block?  With the crescent shaped water passages on the 289 not present on modern heads (iron or aluminum )is this an issue?

289 heads.