Can someone tell me what’s the advantage of using 1967 big valve heads over let’s say 1970 to 73 heads. Is it better to port the 67 heads or buy SE aluminum heads. Or should I just leave the heads alone. It’s going on a 430 block with oil mods and bored 60 over with a ta 212 cam. Thanks
First a 2 questions needs to asked, that being 1) how much HP are you looking to make and 2) how will the car be driven the majority of the time?
If you're going to spend the money porting the heads you'll be money and lbs ahead buying the TA alumn heads.
Some 67 heads were big port, not big valve. Big ports flow a bit better. Porting is always worth some power, it’s just expensive unless you can do it yourself. Aluminum heads will out flow them all right out of the box.
The advantage of the "big port" heads is that they flow a bit better than the later heads and you don't want to do any porting or can't. If you start porting "big port" heads then it doesn't matter what you start with, you could've started with the non big port heads and you can get to the same place, just requires a little more porting.
Closed chamber increases compression over open port heads, and taller ports as stated, help flow. Used to be a desirable/sought after bolt on before the advent of aluminum aftermarket heads.
If I recall reading somewhere b4 the factory bug port heads were roughly 3-5% more than the standard head .........but I'm pretty sure if you just would take the time to gasket match and just smooth out all the rough casting flaws, not really open or reshape the port you could get at least that. I did a set when I was in college.......b4 I pulled it apart.......out by the very last bolt holes on all 4 corners I drilled a small hole through the intake into the head the size of a small diameter roll pin. I used this as a line up guide. Once apart I could position the gasket where I line up best, refill the hole in it to the head and use the pins to keep it in place while i scribed the openings on both the heads and then the intake. From here just blended out to my Mark's, smoothed out the rough nasties in all the ports and same on intake. Then drill on new intake gasket you will need to drill the same lineup holes to have it match the ports......on assembly use long enough pins to go back into the holes to make sure everything is lined perfectly up, just apply enough bolt pressure to make sure nothing is going to walk around, remove pins and torque down. I still use the pins even on my my new aluminum heads I think all my effort was worth about a tenth and a half, if I recall correctly from more than 20 years ago. As in comparison I sold a set of nicely ported iron heads with big valves to a board member the other year, heard back after replacing stk heads, the gained 5-6 tenths. I would guess if you had to pay someone to port the heads, redo the valve job correctly to install large valves. You will be 1200-1500 or more. So close to 3/4 the cost of aluminum heads, with no more gain in the future and still be behind in flow numbers because most ppl cant get flow number in iron heads to beat out the box aluminum.......and those that can often get more in their work than what aluminum heads cost
