302 heads on a 408?

[88Stangboy]

ive already posted something about this before.
My friend Kyle is building a 408 for his 95 GT like i said before.
He is looking for some heads, he doesn't really have alot of money
to spend on them, i didn't know if my heads off my 306 would work?
Something about the bolt holes not being large or to large, but i was wondering more about the flow stats, would they be big enough to support the 393 with a Trick Flow stage III cam? They've been completely ported on intake and exhaust side, etc. 2.02 intake 1.60 exhaust, they're 71' closed chamber heads, i think they're 58cc not sure A38's. But are the ports just to modest to begin with? even with the port job on them i dont think they'll support his engine but i was just asking to make sure.

 

[RS200]

The 351W heads will fit on 302W blocks, and vice versa. Same engine, but the 351W has a taller deck, which means he'll just need a 351W intake to fit your heads. I don't think they'll be enough, quite honestly.

 

[dastang2]

you would have to drill out the bolt holes to fit the 351 head bolts on them.

 

[FORCED2DV8]

I would just look for a pair of 351 heads, junkyard or classifieds and have them machined and do some basic porting. He will get much better performance.

 

[vristang]

What is the difference between the 351 head and the 302 head?
I thought they were the same.

I ran my stock 302 E7s on the 351w for several months. Not much power in those heads. The 408w will be asthmatic with stock heads.

jason

 

[HardmanGT]

Asthmatic is an understatement for those heads. A 408 needs a lot more air than a 302, about 30% more just as a beginning.

Find a set of aftermarket heads. Save up for them. Trade, barter whatever, just don't waste the time on 302 heads

 

[88Stangboy]

i was thinking they were a little small, but when i looked up the flow numbers for the 351 and 302 heads, they're pretty much the same. I mean, the heads are mine and im getting ready to do a 393 build up and i dont need them and he offered me $300 for them as they are. They're a little big for my 306 with all the port work they have done to them, the guy i got them from had them on a 347. We already knew about the bolt hole prob. But i just told him i thought they would choke his engine down in a little bit, theyre definatly not stock heads, the intake runners a good bit larger than the E7's, and as i said they have bigger valves installed. But i still dont think theyre good enough with a Trick Flow Stage III cam. the casting number on them is A38, i was told theyre off a 1971 Maverick by the guy i got them off from.