7.4l cylinder heads.-gctid816261

[sketch96]

Pulled the heads off my 2859. Took them to the machine shop to have a look as I found a fair bit of valve leakage during a leak down test. The motor had approx 500hrs on it. The seats are pounded out and are junk.

I'm looking at replacing them for approx 1000 to 1200. Or buying a new set of aluminum 6045 edelbrock heads. I can get them for a pretty good deal. 2000 complete out the door.

So question to the pros out there. Anyone have any input on using aluminum heads on a heavier boat like the 2859? The motor has been rebuilt a few years ago and is a 496 now. Full fresh water cooled so no corrosion issues. Just wondering if anyone has had an issue with switching over to aluminum.

[yachtman]

I have run aluminium edelbrock rpm heads on a few different boat engine. I'm guessing you have closed cooling system. If no closed cooling dont even think about it.

The nice thing about aluminium heads is they run cooler and have less chance of predetonation.. You will also lose some weight.

I don't know about the heads you speak of however for example the sbc rpm head has a fast burn cylinder chamber and improved runners and is good for a 60 hp power increase. Perhaps the head you speak of is similar.

If it were me and I had closed cooling I would do it. Good time to get a up grade aluminum intake manifold that is port mached for even mkre weight loss and better air flow.

I wouldn't go willy nilly about it though. Here is your chance to do a good head to piston clearance and bring it into a quench situation. For better economy and performance. If you don't know what that is I can explain. If you have dished piston though its a moot point i like head to piston clearance about .040 all that is needed is to chose the head gasket thickness acordingly so that the clearance is about .040.

[sketch96]

Yes. I have a set of soft "setup" valvesprings I will install to check piston to valve clearance. I will also need to check pushrod length. Don't think they are stock length. The motor already had an aluminum weiand Action plus intake. I'm going to go with the Hge aluminum. Exhaust system. Should be a significant weight loss to go along with the 180lbs of concrete I removed.

The heads are edelbrock rpm heads. Model 6045. The machine shop figures I will gain a almost a full point of compression and approx 20 to 30 ft pds of torque. Better fuel economy. With the better cooling and combustion chamber detonation isn't a problem. I wanted to hear from someone who has run them on a heavier boat just to see if they had any other issues at all. Sounds like a win win right now.......

[mister_larry]

Better economy, better cooling: it does sound like your win-win. I would just remind you how soft aluminum is.

It looks like you trailer the boat - keep it up. If you keep it in the water all summer you might really load it up with zinc. Even if you keep your circuits "clean" your neighbor in the marina might not. Too many good aluminum parts have been lost to stray current - electrical that is.