Basic Stroker Build

[brielly]

Hey there stroker newbee here lookin to make my first build. Here's what I have. 1982 jeep Cherokee (full size) with 4.2 and mopar efi. It runs great and pulls the truck ok but stops pulling at 3000 rpm's. I figure a basic stroker with more torque that's capable of revving 4000-5000 rpm will make my truck much more fun to drive. I like the idea, simplicity and price of the poor mans stroker but it looks like the Sealed Power 677CP pistons are hard to get. Can I just use stock pistons and maybe go with a .20 or .30 overbore? Rock auto has sealed power 677ap are these similar? I already have a 94 4.0 so I just need to get another 4.2 so I can build the engine while still driving.

[Cheromaniac]

I like the idea, simplicity and price of the poor mans stroker but it looks like the Sealed Power 677CP pistons are hard to get.

No they're not. They've merely been renamed as Z677AP and you can get them from Rockauto (as you already know) and Summit Racing. The other alternative is to use the 4.0L connecting rods with IC944 pistons and build a modified poor man's stroker.

[brielly]

No they're not. They've merely been renamed as Z677AP and you can get them from Rockauto (as you already know) and Summit Racing.

Thanks for clarifying that. One thing I'm not sure of Does the over bore effect the compression ratio?

[Cheromaniac]

One thing I'm not sure of Does the over bore effect the compression ratio?

Only very slightly.

[brielly]

Ive been reading about quench height and emissions and i'm a little concerned about passing the sniffer test here in NJ. I see the modified poor mans has a .070 compared to the .088 of the poor mans. Would this make a difference worthy of spending the extra money on the keith black pistons?

[SilverXJ]

Quench greater than .060" isn't doing anything, no real squish/quench effect.

[brielly]

Quench greater than .060" isn't doing anything, no real squish/quench effect.

Could you elaborate on this? I know the smaller number would be better but I don't see that option for the strokers in my budget range. I'm mostly concerned with getting a reliable engine that will pass emissions and not squeezing out every last hp. What is the quench on a stock 4.0?

[SilverXJ]

Could you elaborate on this?

Its just too much room for any kind of effect.

What is the quench on a stock 4.0?

Stock deck clearance is around .0225" + .051" stock gasket = .0735" Quench.

[Cheromaniac]

Ive been reading about quench height and emissions and i'm a little concerned about passing the sniffer test here in NJ. I see the modified poor mans has a .070 compared to the .088 of the poor mans. Would this make a difference worthy of spending the extra money on the keith black pistons?

My traditional poor man's stroker has far lower emissions than my old 4.0 ever had, and that engine was still going strong.

[brielly]

Thanks guys sounds like I'll be ok with the poor mans stroker.

[brielly]

Just spent the day ripping out the crank and rods from the old 258. Now I'm plugging numbers into the calculator on this site and things aren't adding up for the compression numbers on the poor mans stroker which supposedly has a 9.2 scr. I'm getting an scr of 9.87.1 and dcr 7.29.1 quench: .0725 This is assuming a 13 cc dish on the 677cp pistons. It drops to 9.43 and 6.98 with a 17cc dish.Unfortunately Im not sure what the correct dish is on these pistons since both numbers are listed in the FAQ pistons page. Anyone know for sure?

My other thought is to zero deck the block. Grab some silvolite 2229's, have them dished to 22 cc's and i'd have an scr of 9.45.1 dcr- 6.99.1 and a .051 quench. The .043 gasket raises the scr to 9.6.1 dcr- 7.1. Would these compression ratios be ok with the stock cam?

[Cheromaniac]

Just spent the day ripping out the crank and rods from the old 258. Now I'm plugging numbers into the calculator on this site and things aren't adding up for the compression numbers on the poor mans stroker which supposedly has a 9.2 scr. I'm getting an scr of 9.87.1 and dcr 7.29.1 quench: .0725 This is assuming a 13 cc dish on the 677cp pistons. It drops to 9.43 and 6.98 with a 17cc dish.Unfortunately Im not sure what the correct dish is on these pistons since both numbers are listed in the FAQ pistons page. Anyone know for sure?

I cc'd the dishes in my 677Ps before I installed them and they were definitely 17.5cc. I was somewhat surprised 'cause I was expecting a lower number so I checked them again and they were still 17.5cc. I used the same method to cc the original stock pistons and they came in at 13.1cc. Quench on the original poor man's stroker is 0.088" and my engine's SCR came in at 9.24:1.
Speed Pro quote 13.4cc for the 677Ps (same as H802CP/H825CP) so if you use that number in the compression calculation it comes to 9.62:1.

[brielly]

• Plugging in the numbers with the 17cc dish I'm getting scr 9.59 dcr-7.09 quench 0.0645 These numbers actually sound pretty good but dont match up to your poor mans stroker numbers. Am I plugging in the number wrong?

[Cheromaniac]

quench 0.0645
Am I plugging in the number wrong?

Yes. The deck clearance is 0.045" and the head gasket thickness is 0.043", so that makes the quench 0.088" on the original poor man's stroker.

[brielly]

The calculator has the stock deck clearance at .0215. Is this correct? Sorry for all the questions I just want to be accurate.