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I found that it already has a .30 over bore.
Have your machine shop check the cylinders. If they make 4.030", you may get by with simply cleaning them up.
Heads looked good, but need to have them checked.
Again, regarding the combustion chamber volume, these must compliment the piston profile, or visa-versa.
IOW, I'd not assume that the last build was Marine Correct!
Check casting numbers!
I'm not sure of the size of crank or cam, but I know that crank needs to be turned or replaced.
Nothing wrong with a turned crankshaft!
I keep hearing of these quench pistons. I guess there is alot of opinions on these pistions.
Yes, lots of opinions I suppose.
Do some homework and reserch, and learn what the Quench Effect or Squish Zone accomplishes in the SBC.
If you find some good articles, they'll even go into details on Detonation control, increased Ignition Advance, how this affects LPCP, low end torque, etc...... all of which is good stuff that the full dished piston just cannot accomplish.
The quench or squish is nothing new with any engine whereby a portion of the chamber is wedge shaped.
The Chrysler Wedge Head boys have been doing this for years!
The original 1955 265 cu in GM SBC engine was designed using a flat top piston coming up under the wedge area of the cylinder head, which gave this engine a quench area.
In the 70's, GM screwed this all up by going to the full dished piston.... and they continue doing it today for the GM SBC line that we see in our boats!
Machine shops are so familiar with seeing this silly piston, that most don't even question it..... let alone know about the Q/E or S/Z.
Some will even give you that "deer in the headlights" look when you ask about a quench build!
If the customer does not specify that they want a Q/E build.......... then before you know it, they've grabbed new full dished pistons, and your build end up being no better than what GM did originally.
Now we're back to using a very conversative Ignition Advance (as to throat off "Detonation Potential"), our LPCP ends up being on the weak side, and we don't get the low end torque potential, etc. etc.
After you research this.... I'll offer a Gentleman's Wager that you become on board with the concept.
Why is the deep dish better than a flat top. I'm assuming it's a better swirl cup.
Again, it's the piston deck profile that we want to "mirror" the wedge area of the combusion chamber. When this deck area mirrors the wedge, and when we bring this dimension into approximately .038" or so...., we gain the "quench" or "squish" that we are looking for.
IOW..... we do not want any dished area underneath the wedge section.... the full dish piston cannot possibly create a quench/squish.
- The F/T piston works well in a 5.7L with the 76cc chamber heads.
- The low compression Quench, D-dish, or a Reverse Dome piston (with the correct dish volume) works well with the smaller 64cc chambers.
- The full dished piston is the piston that we should avoid..... especially in a Marine build.
Try not to confuse the "dish" of the full dished piston, with that of a quench style piston "dish" volume.
Apples/Oranges!
The dish volume (in either style piston) is simply there to control compression ratio.
Don't know what to do with the cam yet. Mainly because I don't know what it has in it. What size cam is in a 383, Marine motor?
Deside upon your build, and then call someone like Comp Cams for a suggestion.
These people know better than us as to what profile to use.
I have a high rise eddlebrock torquer intake. Don't know how good this intake is or isn't.
The Torker is a single plane manifold, and would not be a good choice for a cruiser style build.
A good Dual Plane intake is what you'll want, IMO.
Also..... if this is Raw Water Cooled, the aluminum Edelbrock automotive manifold will eventually fail.
This is a single plane intake manifold:
Rick
Well, thank you for your help. I've desided to buy the Vortec heads, but I'm going to have to find out what the valve sizes are. I'm not sure.... 1.94 intake and 1.5 exhaust?
1... with what chamber 76cc?
2... I'm looking into a .450cam.
3... The pistons that are in it now are 4.030 Flat tops and in good shape. So, this is a good thing.
4... Going to look into the other pistons.
5... I'm going to have the engine line bored and the clyinders de-glazed and block decked.