My rebuilder and I have been talking about my 225 since I brought it in for a spun #2 rod bearing and have decided to bulletproof the thing. My main objectives are to make the engine as durable and smooth as possible without drastically changing its appearance. We agreed that building it to marine spec is the best route. Forged pistons, copper coated rods, painting the inside of the block with Glyptal, etc, though I thought loosening the main bearing gap would be unwise since I dont plan on using super thick oil in the thing. I'm still deciding whether to use a super 6 intake. My question is, assuming I'm starting with an industrial 225, what tweaks can we use to make this engine even more durable and especially more smooth? I'd like to be able to balance a nickel on its edge on the valve cover, ideally.

Open-up the oiling system and deburr the crank and con. rods. Then rebalance the rotating assembly. A good aftermarket vibration dampener is also a good idea.
The "long rod" engine is a good way to go seeing that the 1.7 rod ratio puts less stress on the rods and pistons.
DD

I'm not sure if he's deburring the crank and rods or not.

We did agree very early to get it all dynamically balanced, and trim the parts to equal weight, etc.

Long rod engine, eh? Ive heard the term but honestly don't know if I have it or not. I hope it doesn't mean I'll have to replace the crank I just got rechromed, as well as the copper rods I just bought to go with the forged pistons... and speaking of which, I read somewhere on the engine page of allpar that some fleet engines came with an extra oil control ring; would the marine pistons be the same? I'm wondering if another forged chrysler piston with the same deck height would fit this engine if I bored it .030 or .060 over.

Now that my spare engine has had the crank opened up to fit over my torque converter, Im not in as much of a rush for the original and I can get more anal with it. There are a few speed shops in my area, mostly catering to teens but they might have access to a viscous dampener, if there's any interchange between the /6 and a V8. Are you aware of any? Ideally, Id rather not have to bump all my pulleys out to make it work, since Im trying to keep a stock appearance. I'm even going so far as to have the painter coat the area under the manifolds gunmetal grey before theyre installed and the rest of the engine painted blue!

Lighter pistons ought to help make it a little smoother, careful selection of the camshaft also. I don't know too much about the aftermarket balancers. I've heard the Chevy 292 has much less crankshaft problems when an aftermarket balancer is used, I've also heard that some of the expensive balancers might not work as advertised.

I was thinking of ratio rockers to increase lift, but I don't want to mess with duration; THAT will definitely mess up the idle. Maybe more lift would too; I don't know...

To be honest I'd rather port and polish with stainless valves and maybe bigger valves, but seeing as how the super six intake and stock Holley 250 is the biggest setup I can hide, smoothing over any turbulence is all I have in mind.

well with viscous dampers I know that if you drop one and trap the counterweight inside, it acts as another flywheel and actually magnifies torsional vibration, which will break your crank. These 'rattler' dampers Ive seen advertised I have no idea about.

It's settled. My boss has a 74 Duster with a super 6 and he's agreed to sell me the motor and trans for $100. Ive asked my rebuilder to crossdrill the crank and do a mild porting job to accommodate the super 6 intake. Do you all think there's any point to nitriding the crank while it's getting redone?

I'm still foggy on what else to do to the head. I want to make as many tweaks to the head as I can without roughening the idle. Can I put bigger valves in? What about stainless valves? Can I mill it and match the head volumes and still keep it smooth? Anyone know of any ratio rockers out there, and will they make the car run any rougher? Do I need to notch the pistons or am I safe? Will correcting core shift actually make any tangible improvement?

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