what are the advantages if any of using 78 351w heads on an 85 302? I'm looking for some decent power without having to spend alot of cash.
none, the 78 still a smog head.
if you want stock 351 heads you need the 1969to74..
if you want 302. then aftermarket the way to go. check ebay if you want some good price.
i got two complete set 351 ready to bolt on.
1970 was $450.00 ship included and 1974 was $250 shiping included.
alright now my question is what is the difference between a smog head and a non smog head?
on the smog head.
the exhaust port is smaller(bump) around the exhaust port roof, next valve guide. so to let air come in from the smog pump.
inturn cause restriction in the exhaust flow.which makes your engine work harder to pump the exhaust out.
none smog heads .
do not have the bump ,so it flows easier.
some people have ported the bump out but that only works on some heads.
like the 1974 to 1980 351cleveland/351M/400- 2v headS .you can not port the smog bump out because ford raise the top part of the exhaust port of the head to be even with the bottom of the valve guide.
so I shouldnt worry about changing the heads then. the reason I ask is because I will have the intake off to be replacing the cam and installing a new intake and carb setup. I plan on using the edelbrock performer kit. so any added info would be helpful.
your 85 302 heads are just as good as the stock 78 351 heads. they both have the same size ports/same size valves. so you would not be upgrading .
the only way to upgrade the 78-351 is to have them work over. with new 1.90 intake/1.6 exhaust valves plus have the exhaust ported out.
Gt40 heads can be had at junkyards for around $200. That would be the way to go.