I'm going to be dipping into my shortblock for a basic build up. I'm looking to keep the costs down for the first buildup. So basically I'll be going in for a clean up with new rings bearings etc. What I have so far that I'll be using is an MP .460/.460 lift 268/268 duration camshaft , clifford intake with 400 cfm carter afb carb , MP 6 into 1 header , I've matchported the head with some bowl work. I'm thinking of going with either 3:55's with a low gear planetary swap to achieve approximately a 3:91 ratio in first and second , or just straight 3:91's aswell , I'm trying to decide between one of 3 convertors (going with MP turbo action's due to cost as I work at a chrysler dealer and get MP parts for cost + 10%) T-A 10" 230k , T-A 3800 250k or T-A 4200 263k ?? also what compression ratio should I shoot for and how to achieve it ?? mill head and block ?? how much can be milled before shorter pushrods are required ?? As well , I'm thinking of using the MP stainless swirl polished , back cut valves for the same cost effective reasons as above ?? Any and all suggestions are greatly appreciated thanx in advance

Hey Squeek,

Here are some thoughts:

If you are not grinding the crank, get it polished to open up the clearances a bit. If you have the dough, I recommend going with new oversize (cast) pistons, like Silvolite or Enginetech, and grinding crank, resizing rods, balancing rotating assy. I recommend 0.015" on rod bearing clearances and 0.015-0.002" on mains.

Go with at least the 250k converter since that will probably give you around 2800-3000 stall. I'd advise staying with the stock 904 gearset and getting 3.91s if you can tolerate the highway revs (or don't drive much highway). The wider 904 gearset makes for bigger drops on shifts and keeps you out of the power band more.

You can get away with about 0.090" mill/deck w/o new pushrods, but I've heard some have had a little trouble even with this amount. New pushrods are not expensive, so just get the comp you want and go from there. Sounds like you should shoot for about 9.5:1 with that combo, so go with a ~ 0.100" mill (after you measure deck height to see if it's near the 0.141" spec). Personal preference on block or head milling - depends on future plans. Maybe take 0.060" off head and 0.040" off block?

Big valves are good. If you do this, get them to cut the bigger seats, then port and blend, then have the valve job done.

Cheers,

Lou

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Home of Slant6-powered fun machines since 1988

thanx Lou

Upon disassembly , I'll make the descision about new pistons depending on wear etc. If the clearances are nearing the extreme , then I'll go that route for sure (which would also make me feel much more confident about potentially putting her on the bottle) . I've noticed that the 9.0:1 mopar cast pistons aren't listed in the 02 performance catalog , so I'm assuming they've pulled the plug on those. They've pretty much been dwindling away all the performance slant stuff over the last few years. Your probably right about the pushrods and I should pick up a set of "hardened" performance ones , I've heard that the factory pushrods can seem fine yet flex quite a bit under load thus robbing power. Advice taken on the planetary deal , probably would be better off just sticking to 3.91's. I really don't forsee much highway use at all and the local track is only about a 35 minute highway trip. Is the .141" spec you mention the "in a perfect world" spec for the stock deck height ?? Thanx once again

Squeek,

That deck height is the spec for at least the '60s Slants (piston top to deck at TDC), and I've seen some that are over 0.200" measured.

Those MP pistons are really not a big deal. I bought a set of the 0.060"-over back in '92 (in my '64 motor), and they had almost exactly the same comp height as the stockers I pulled out. I think they were TRWs. Not really 9.0:1, so you'd have to do plenty of milling anyway.

Happy building,

Lou

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Home of Slant6-powered fun machines since 1988