If you are dead set on Iron, Dart makes "Iron Eagle" but they are costly. As previously stated going to aluminum has more benefits than Darts with virtually the same price.

Last edited by Rudi (9/29/2016 3:35 PM)

Modern aluminum heads on a naturally aspirated engine shouldn't have head gasket issues.  Blown applications are always going to have problems because the small block Ford just has too few head bolts.  I put studs in instead of bolts on almost every engine I build for cheap insurance, regardless of make.  You can o-ring the heads if you are really worried about it, but again, I would only go to such extremes when running a lot of boost.  The decks on most aluminum heads are 3/4" thick, whereas iron heads I've seen them as thin as 3/8", sometimes thinner if they've been milled a lot. 

Yes, there is a bit of a double edged sword with aluminum as it pertains to heat retention/rejection.  Iron tends to hold heat, so a lot of people feel that iron headed engines in theory make more power at the same compression ratio than aluminum heads, all things being equal.  The counterpoint to that theory is that because aluminum rejects heat much faster than iron you can safely run another point of compression over iron and not have to worry about detonation, again, all things being equal. 

My experience has been that all things are never equal and you build the engine to achieve your goals and match the parts accordingly.  We ran modified iron heads for years because aluminum heads were too expensive.  In the '90s the cost of aluminum heads came way down.  They were still a bit pricier than iron, but companies like Edlebrock revolutionized the casting technology to really get the cost down, and the cost of the heads if anything has continued to go down over the years, especially accounting for inflation.  I used my first set of aluminum heads in 1998 (Edlebrock 6073 castings for a SBC that I've since reworked and are still going strong with the second engine under them).  I never went back to iron.  I've investigated them several times for both Fords and Chevys, as both have decent factory offerings that are in theory cheap (GT40/GT40P and Vortec respectively), but the problem is that they both have all the same problems and need massive rework to work on a real performance engine.  I've been very happy with Edlebrock's offerings.  They are an entry level head at roughly $1,000/set.  They don't flow quite as well as say AFRs, but the cost to benefit on them is probably higher than the AFRs, because that little bit more the AFRs get you costs quite a bit more.

I would be sure that whatever you do you build a matched combination.  Compression ratio, head intake port volume, camshaft profile, intake manifold, carb, and exhaust all have to be matched to get good results.  There is no one magic part that turns an engine from a commuter to a dragstrip hero.  Heads are a good starting point, and have the potential to make a massive improvement, especially if you are running 60's, 70's, or early 80's era heads now.  BUT, you need all the parts to work together to get the most out of those heads. 

Hear is a good price on some heads.

https://pittsburgh.craigslist.org/pts/5777277115.html

wsinsle wrote:

Hear is a good price on some heads.

https://pittsburgh.craigslist.org/pts/5777277115.html

Those heads retail for like $1,500 through Summit, so the price is good.  The intake runner is a bit big for a mild build.  On a 302 these would be a bit big unless you are shooting for 350HP or more and will cam accordingly.  These would work well on a stroker or 351 shooting for 350-450HP. 

BUT, at 70cc the chambers are way too big.  The problem with a 302 is that the stroke is too short to get a reasonable compression ratio with normally sized chambers.  With a 70cc chamber you're going to be about 8:1 with a flat top piston, the piston 0.010" down in the hole, and a 0.030" compressed HG thickness.  If you went to a 58cc chamber, which is about the smallest I've seen on a production aftermarket head you still only get to 9.3:1 all things remaining constant.  You'd have to get to 50cc to get 10:1 from that 302.  You could run a thin HG, but then you lose your quench distance and probably have to worry about the piston smacking the head.  I won't build an engine that doesn't have 0.040" quench distance; it just isn't safe.  The best bet would be to mill the heads about 0.090" to get to a 50cc chamber, and then you'd need to mill the intake like 0.200" on the head sides and 0.286" on the bottom to regain proper fitment.  You also would need to check PTV clearance to use a performance cam ground for use with that 10:1 compression ratio.  You can cut the valve reliefs in the pistons deeper without pulling the pistons, but its a time intensive proposition (bolt and unbolt the head 4 times per side).

Be wary of different water port configurations on 5.0 vs 289/302 blocks.  Heads need to match the block.