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 reference 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

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'68 Barracuda - taking advice on increasing street torque, power, & road handling. Click To See It

I'm planning a similar build this Spring, as time and money allow. I do suggest ripping the rod bolts out of those 198 rods and using ARP rod bolts. I'm not sure which pistons are the best for your projected compression ratio. but hopefully others with more experience can chime in here. But new rod bolts are a peace of mind/one less thing to be worried about if you plan to rev it up occasionally.

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If it was easy, everybody would be doing it.

I agree that you should have the rods "rebuilt" (resized, new bolts, check tolerances). I am not sure what are the best pistons from an OEM perspective. The Wiseco piston kit should work well, but you may have to bush the rod small ends? 2.2L Mopar should work. You do not need forged pistons to make that power. Keep revs below 55-5800 RPM. Get the whole rotating/reciprocating assembly balanced.

The BIGGEST factor, by far, in making power on a Slant is the cylinder head flow (porting, larger valves). Make sure you have a killer head, or everything else will not give you good results. I used to tell everyone to go to Mike Jeffrey, but he has retired from building heads. I wonder if Doug Dutra (Doctor Dodge on this forum) would build you a head?

I like your compression ratio and cam choices. Degree the cam at 100 deg intake centerline for best all around power and performance. You really should not need valve reliefs in the pistons with that cam and compression ratio (deck height), although you should check it in the end with play dough after assembling the short block.

That's a start, anyway...

Lou

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Home of Slant6-powered fun machines since 1988

Great advice Lou and coconuteater64.

Lou - I'm thinking 2.2 pistons might be an economical solution while still hitting my goal, looked into Wiseco and KB, the latter is being considered - but 2.2 seem least costly. Low RPM is the order, and absolutely weight & assembly balancing are in the plan. Head work by Doug would be awesome! How would I check his availability/willingness? Also appreciate the setup tip - noted. Greatly appreciate your input -Chris

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'68 Barracuda - taking advice on increasing street torque, power, & road handling. Click To See It

You can use a V-6 Chevy piston on 198 rods and come out at a near zero deck. Pin diameter is close to standard Slant 6 pin.

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

Wow Rick. That could open a lot of options. What engine family would I look into for that? Thanks a bunch! -Chris

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'68 Barracuda - taking advice on increasing street torque, power, & road handling. Click To See It

198 con rods are hard to get these days so my advice to anyone thinking about building a long rod SL6...
Get the 7 inch c to c connecting rods "in your hands" before ordering any other parts for a long rod build-up.

As for piston choice... most 2.2 pistons work fine so it comes down to the compression ratio "math" and how much dish / valve relief pocket you need to get the CR where you need it.
(note: a 2.2 valve relief pocket does not line-up with the SL6 valves. This is important if the 2.2 piston selected has an off set piston pin)
DD

When I built my 198/2.2 motor the KB pistons were dirt cheap but the pounded you in the azz for the ring sets.

I used the turbo pistons with the 18 cc dish. With no milling it comes out very close to 9.7-1.

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Official Cookie and Mater Tormentor.

I have a 198 rod, 3.1L Chevy piston motor in Project V that has made about 240-250 HP. Hypereutectic (cheap) pistons and rings...

I think you already have the rods, right?

Lou

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Home of Slant6-powered fun machines since 1988

And mine were out of a 2.8L

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

I think they are probably the same piston.

You can find general piston catalogs online with the piston pin (center) to piston top height, usually called the compression distance or height. KB/silvolite has one, mahle has one... These catalogs list bore sizes, oversizes, ring dimensions, dishes/reliefs/domes, etc...

Lou

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Home of Slant6-powered fun machines since 1988

Here's what I found on a good ring choice for 2.2 and 2.5 pistons: http://www.slantsix.org/forum/viewtopic.php?t=25197

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Joshua

How close are those Chevy pistons on the 198 rod? Is it a press fit?

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If it was easy, everybody would be doing it.

I'm fixing to start this very same build. I'm going next weekend to pick up a 198 short block. I've found the Erson Cam that's been suggested but I've been comparing it to the Hughes Racing cams as well. The Erson lift and duration is smaller than the the Hughes Cam. Of course both companies don't suggest the others cam and its hard to find real world input on them.

I would guess that Hughes will not work well with a Slant 6, and I do not know if anyone knowledgeable here has used one. Erson should be good, depending on which grind. What are you trying to accomplish with the build? Budget, comp ratio, fuel requirements???

Lou

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Home of Slant6-powered fun machines since 1988