198 Rods + 2.2L Pistons - advice needed

There's a lot written about using 2.2L pistons and longer 198 rods in the 225 - has anyone documented the process beginning-to-end? I read Dutra's stroke article which is great, but I'm wondering if any improvements or part options occurred since that was written. Or lessons learned.

Looking for deep advice - especially on part selection. Rebuilding an NA '68 225 for 230+ HP - street use only - not a redlight racer.

Parts planed so far: OCG #346, 1.7 & 1.4 valves, 300# springs (says OCG), about a 3.5" bore, 10:1 compression, Edelbrock 500 AVS, 6:1 headers. Hoping to minimize milling by using this setup which will allow me to put more $$ into the head (port, bowl, chamber) to increase velocity and filling. Need to use pump gas (any grade but no additional additives like an octane boost) - fuel mileage not important.

Questions:

• Are some piston part-numbers/designs better than others for my purpose? I see some with a trough, some with 2 or 4 reliefs, flat-tops, recessed - any thoughts on which provides the best performance for my needs?
• Any special rod prep needed? Clegg and BP offer reconditioned rods, any preference in vendors work?
• Any special block/head prep (other than a light cut and runner/port blending)?
• Anything I didn't ask but should know?

Thanks as always!
-Chris

Get in touch with whitepunkonnitro he can get you setup.

I am always leery with mass re-conditioned rods.... I got a set of 8 once with center-to-center length variations of .019" ! (They went right back...) But I can't say anything specific about those 2 shops.

If you are shooting for that 10.0 SCR, then the KB239's listed are going to get you very close with head milling in the .030" range or thereabouts. Start out with measuring the chamber volume in your head and work from there with the info the Dutra article on how much to cut for each 1 cc of reduction. If you use the KB's, follow their instructions on the ring gaps EXACTLY; the top rings are high and you need to use their gaps to avoid expansion problems.

I am an advocate for pushing up SCR and DCR on the street (for the sake of low RPM torque) but the /6 chamber does not have a reputation for being particularly good for avoiding detonation. So if you do go close to 10.0, you are going to have to be conservative with the distributor advance curve and the overall ignition advance. But, I have not looked at your cam specs and the resulting DCR so take that just as a general caution.

If you are not into computing DCR yet, then look up the Pat Kelley DCR calculator and learn how to use it; you need to learn how to compute piston-to-deck heights, read the data from the piston mfr's, and what head gasket thicknesses. Armed with that and your cam data, you can figure up DCR. If you get to a DCR of the high 7's or 8.0 then I would stop at that and not go higher for this engine.

It's probably hard to read but here is the SCR computation for the KB239's with 57 cc chambers and a .039" thick head gasket. (The 2nd is a duplicate which I can't edit out....)

I have no idea if the coating will do anything to reduce detonation here, but I am rather dubious. There is a lot more to it than just hot surfaces. The chamber here is kinda spread out and not closed, and that slows the combustion process. Slowing combustion tends to increase the likelihood of detonation and a coating would not change that.

I am not sure I follow your comment on the KB's versus 2.2 pistons. Those KB239's ARE for the 2.2L engine ..... ?????
KB Hyper Piston - Chry 2.2L Rod 5.945 Flat Top 5cc 2V [KB239] - $222.46 : United Engine & Machine Co. Incorporated, Performance Pistons

They are good quality hypereutectic pistons, are made for what you want, and the price is not unreasonable. What other 2.2L pistons are you considering?

nm9stheham said:

I am not sure I follow your comment on the KB's versus 2.2 pistons. Those KB239's ARE for the 2.2L engine ..... ?????
KB Hyper Piston - Chry 2.2L Rod 5.945 Flat Top 5cc 2V [KB239] - $222.46 : United Engine & Machine Co. Incorporated, Performance Pistons

They are good quality hypereutectic pistons, are made for what you want, and the price is not unreasonable. What other 2.2L pistons are you considering?

Click to expand...

My personal opinion: The price of those pistons, is for one set of 4 pistons, that means 2 sets would cost just under $450.00, plus you need to buy rings. For another $100 you could get the Wiseco forged pistons, with rings included.