madscientist said

You are pretty close in your thought process. The majority of the heat in ANY cylinder is the top 2 inches or so. If you have a 1/2 inch thick deck (or .750 with an X block or 1.0 with the R blocks) the very hottest part of the cylinder is solid. That's why they made open top blocks....upper cylinder cooling in long distance engines. There is very little heat in the bottom of the cylinders, so it's really wasted space. The factory COULD fill it with cast iron, but cost and weight make the bean counters lose their minds. But...you can fill up the space.

I use Hard Block about 90% of the time. I have used Moroso the rest. Never had issues with either. I am 100% sure of this because I have cut up several blocks (of the 3 major brands) that were filled and used up and never had any seperation or any other issues.

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madscientist said

OK lets look at this post. I obviously left some things out I shouldn't have, and will point out some other things.

1. NEVER EVER use a stock pan with a filled block. EVER. I always use at least 8 quarts. You can't cool an engine with 4 quarts in the pan. The oil spends too much time in the engine. Mistake number 1.

2. A 3 core radiator means little. Fin count, tube diameter, multiple pass etc. all make a difference. You damn sure should have had an 8 blade water pump, preferably the Milodon part number, which has the back of the impeller closed off. You'd be surprised what closing off the back of the impeller does for water flow, and FLOW is everything.

3. Since I do this for a living I don't always give all the details I probably should. If you fill the block and don't want to run 8 quarts of oil you either MUST run 20w50 oil (or even 20w60 or better yet, Torco makes a 10w60 that would be perfect) or you MUST close up bearing clearances. A scuffed bearing or a spun bearing only happens because of lack of oil.

4. You MUST also increase piston to wall clearance. The cylinders flex less and grow less so clearance must be opened up.

If you follow simple rules you can fill a block and GAIN HP. But you can't skimp. If you do, it will cost you in spades.

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