cutlassefi

I realize there are issues with this comparison, i.e. different dyno, conditions, and intake. But there are also too many similarities to ignore so nevertheless I think this shows the potential of aftermarket heads vs irons.

Jmo.

http://realoldspower.prophpbb.com/po...c20345d#p25105

matt69olds

So, I guess the next logical question should be "Is almost 100 hp worth the money for aluminum heads?"

To me, its a no brainier. The money spent to properly rebuild cast iron heads would come real close to aftermarket heads. Then spend the extra money to either port the cast iron stuff, or try to enjoy the car knowing you have quite a bit of untapped potential.

Unless you stumble across a cheap pair of rebuilt iron heads or are building a stock appearing engine the factory stuff time has passed.

Lars

they way I see it is paying someone to port and flow iron pays for the aluminum in stock form.

coppercutlass

I'm going procomps for the shortblock I'm currently building. I want to run more compression and the aluminums will alow that. Probably buying a set this winter.

oldcutlass

Nice comparison Mark. A big difference with very similar setups.

olds 307 and 403

For the BBO, an absolute no brainer. The SBO 350 is tougher, bigger runners, milling the head and intake, necessary electric fuel pump, roller rockers and MLS gaskets. You can get away without milling on the 403 with Arias pistons and runners would fine on it too. It would nice to be able to buy a ready to bolt on set with 10cc smaller chambers. I realize we are a tiny market but two chamber sizes would be nice.

coppercutlass

I think for an sbo street strip build that will wind up high enough it's still good. It's worth it to be able to run higher compression on the street and a better combustion chamber . Even if you run iron heads you will need to mill them for compression. I have 1500 sunk into a set of #6's that have everything done but port work along with the intake and valvetrain parts.

olds 307 and 403

I know cost is close, when properly rebuilt. In may case to even hit 9 to 1 with 14cc pistons is much easier with iron heads. Chamber is close plus I can use .011" shim head gaskets. I can get a 69 350 for $200 right now, needs an overhaul. On the 424, if I ever get it done, I would have to be a retard to run iron heads. Too bad the Olds 350 is ignored.

Bernhard

Nice comparison it would be interesting how a good ported iron head would have run on the same engine.
I know the aluminum head would come out on top but it would be cool to see how close a well ported iron would stack up on the same engine, would it be with in 50hp?
I think the only reason anyone would want to stick with the iron heads is to keep the car original, or the challenge of running good numbers with a iron headed Olds. There is also the cool factor there is a 9 sec c head engine thread on ROP right know.

brownbomber77

For those of us who port our own heads...it still kills me, my machinist doesn't charge much, so even with new valves, springs, locks, retainers, studs, and guide plates, I'm still in $800 in heads....but I'm cheap....arrrgh....whyyy do they have to make a cheap alternative??? haha