GLENAMY 242SS

iTrader: (1)

As the title says 781 heads best mods
working paramaters:
1) 454/330 bbc stock rotating assy, to remane
2) good currently stock 781 heads going on
2) improved intake/exhaust - edelbrock performer 2.0 stainless marine thru hull
3) not spending a lot

budget mos to head being considered:
A) mill to reduce cc's adding compression
b) inlarge valve size - has stock 2.06/1.72
c) light bowl work
which one 1 do think is best "bang for the buck"?
Which two 2 do think is best "bang for the buck"?

Please no throw them away save and buy aluminum, cam is crap, replace motor - no offense but these are my operational criteria
thank you

SB

iTrader: (1)

3 or 4 threads on the same questions about the same heads is crap.

Just saying.

Factory heads need bowl and SSR work even with stock valves.

Once you increase size, it is more important 'cause if you don't you will have gained nothing by increase of valve size other than lighter pocket and wasted time.

Again, if 2 threads don't get you the answers you want to hear, don't start another.

Evrytime you hit $20 on the ATM machine, you will always get just $20.

Jonesyfxr

iTrader: (1)

As stated above....a few threads on this now.

As I stated in the other thread, we run 781's on a 461 Chevelle. I did the bowl work myself and we stayed with stock sized valves. This is a great oval port head and with minimal work can be awesome. They have much more runner volume than stock heads and help fill the combustion chamber better.

dandercam1

iTrader: (1)

781 heads work great on a mild 454 build. Best bang for your buck IMHO would be go with 2.25 int. and 1.88 ext. valves. A good 3 angle valve job, hand blend the valve job into the bowl area and smooth out any sharp corners in the bowl area. Then do what you can to smooth out the short turn radius. I have seen heads prepared this way produce well over 500hp on a 454. But of course there is more to making 500hp than just a little head work.

Milling the heads for more compression is worth considering just remember if you take enough off the heads to make a significant difference in compression you'll have to mill the intake manifold so everything lines up

Quick2500

If you don't want to spend a lot, leave it stock. If you want to make power, open your checkbook and take it to someone that knows how. You are heading towards a mismatched combo that will end up worse than stock.

motor

iTrader: (3)

To get any meaningful compression increase from cutting heads, you'd have to cut the crap out of them and have the intake milled to match up .If you increase valve size ,you'd have to pocket port ,quality valve job and notch the cylinders to make any difference .Big valves in small cylinders don't work well .Valve shrouding ....Why don't you just take a small surface cut on heads and screw em on. They used the ovals on 330's years ago...If you are aching to do something ,do light bowl work on the 781's with the stock valves ... MO

put it together

dereknkathy

a friend of mine did alum heads for nascar race trucks a decade or so ago. he wouldn't touch iron heads. too much time holding a die grinder for too little gain. at least you aren't trying to make the round ports flow. what about shopping for a set of square port heads?

cp5899

iTrader: (1)

On my last boat I had a 330 hp 454 and tried to build it up for more power. I changed to a mild cam, 781 with port work, bowl work, bigger valves, roller rockers, single plane intake, and a holler 750 carb.

All the time and money netted me 3 mph gain. Looking back I don't think it was worth it, but you live and learn. That was on a 24' Baja so it wasn't a speed demon of a hull either.

On my velocity I went wild bigger cam, blower, heads etc and it was worth the time and effort, but I started out with a 502. The 330 hp motor is not a good platform to big on.

Just my opinion from my own experiences.

dereknkathy

surfed CL by me. several sets of closed large ovals for under 500. cuz you would hafta shave all 3 sides of the intake to fit open chambered ovals milled down that much. worth considering.

Jonesyfxr

iTrader: (1)

Those closed chamber large ovals are hard to come by up here.