Newbie checking in and ready to build!

[pma4x4]

I still need to find 4.2 rods. Cheromanianc mentioned KB944s instead of 4.2 rods. Not for that $$$$!

True, the KB944's aren't cheap but they won't be much more than the combined cost of a set of cheaper hypereutectic 4.0 pistons and a set of 4.2 rods.

I already have the pistons (free) and the rods I am guessing I will pick up for 100 or less. Where is the place to get the best price on KB944s? i have seen $500-600 for a set so far.

[dwg86]

Check with your machine shop. They might be able to get you a good price. Also check out http://www.cnc-motorsports.com/product. ... 443&CtgID=

[pma4x4]

Check with your machine shop. They might be able to get you a good price. Also check out http://www.cnc-motorsports.com/product. ... 443&CtgID=

I noticed you posted about PAW rods. Do you know anything about them. In the past friends and I have purchased parts for V8s from paw. I am just wondering if they ares till a good place to deal with? I wonder if I could request 707s from them?

[dwg86]

I have never bought any parts from PAW, so I don't know about the quality...sorry.

[03GC]

I bought stuff from PAW back in my small chevy days. I probably wouldn't build a "maximum effort" race engine with PAW house parts but for a mild short rod stroker I would feel ok with their stuff. I think they offer a stage 2 rod with ARP bolts for $120.
You can't hardly get a set resized with ARP bolts for that price. I was going to go this route before I decided to go long rod.
Paul

[AIbandit]

I noticed you posted about PAW rods.

My old man said paw built alot of engines in his day. He also said they're a good company. I'll take his word for it. I'm buying their rods (120$ shot peened with ARP rod bolts.)

[pma4x4]

I noticed you posted about PAW rods.

My old man said paw built alot of engines in his day. He also said they're a good company. I'll take his word for it. I'm buying their rods (120$ shot peened with ARP rod bolts.)

Let me know what casting #s you got. Heck post some pics of them weigh them. give us all the juicy info on them. Maybe they are the route to go.

[Cheromaniac]

Let me know what casting #s you got.

It doesn't matter if you have the 352 casting or the 707 casting. They look exactly the same and you can even mix them (I have four 707's and two 352's in my stroker). Just make sure they're weight-balanced (mine weigh 695-696g with ARP rod bolts).

[pma4x4]

Just found out the shop that will be doing my machining has a set of 4.2 rods ready to go, all work done and matched for 35 each.

[Creepyjeep]

So, what is the advantage of going with the 4.0 rods over the 4.2 rods? I am nearly finished with my first stroker build and chose to go with the 4.2 rods. Have I made a mistake? For the next build I will go with the 4.0 rods and the more expensive pistons. This way I can see the difference for myself. I also would like to know if it will be absolutly necessary to replace the stock headers in this ''98 yj?

[pma4x4]

I am on my first stroker build myself but the way it works is there are two ways to stroke the 4.0 I am going with the 4.2 rods with 4.0 std pistons.

1 is using regular 4.0 pistons with 4.2 Rods.
2 is using the 4.0 Rods with the KB944 series pistons. These are custom height pistons. I beleive they are also forged. if your trying to build a high hp stroekr then thats the way I would go.

pros/ cons that i have found. pros on the KB944 setup is you dont have to hunt down 4.2 rods, cons. the piston set is like 500 bucks. Vise versa on the way.

this is just what i have found myself.

[SilverXJ]

The advantage of the KB944 piston is that more of the piston stays in the bore at BDC, which creates less piston slap at BDC. Also, the longer rod is said to make more torque. They are also forged which means they are significantly stronger than the 4.0L pistons used on the 258 rods. That also means that they have to be installed with more piston to wall clearance of .004" and on cold start they will make more noise. It isn't bad just a bit nosier. They are damn pretty too.

[Cheromaniac]

So, what is the advantage of going with the 4.0 rods over the 4.2 rods? I am nearly finished with my first stroker build and chose to go with the 4.2 rods. Have I made a mistake?

No. The 4.2 rods and 4.0 pistons will do fine for a naturally-aspirated stroker that's rarely going to see 5000+rpm. The main advantages of going with the 4.0 rods/KB piston combo are not having to look for 4.2 rods and having forged pistons for forced induction. The difference in rod length/stroke ratio is too small to be of any real significance.

For the next build I will go with the 4.0 rods and the more expensive pistons.This way I can see the difference for myself.

I've already mentioned the main advantages. Another advantage is that the piston pin stays higher up the bore at BDC. The main disadvantages are cold start piston slap, the higher cost of the KB pistons, and potentially higher hydrocarbon emissions due to the larger piston-to-bore clearance and crevice volume required by forged pistons.

I also would like to know if it will be absolutely necessary to replace the stock header in this ''98 yj?

Absolutely necessary? No. Preferable? Yes.

[live24wheel]

The advantage of the KB944 piston is that more of the piston stays in the bore at BDC, which creates less piston slap at BDC. Also, the longer rod is said to make more torque. They are also forged which means they are significantly stronger than the 4.0L pistons used on the 258 rods. That also means that they have to be installed with more piston to wall clearance of .004" and on cold start they will make more noise. It isn't bad just a bit nosier. They are damn pretty too.

I just talked to Keith Black a couple days ago and they were telling me that because of the material they make the 944's out of it is not neccesary to over bore them like regular forged piston... Basically you can have tighter clearances and dont have to worry about any piston slap at all. Any insite on that?

[SilverXJ]

I just talked to Keith Black a couple days ago and they were telling me that because of the material they make the 944's out of it is not neccesary to over bore them like regular forged piston... Basically you can have tighter clearances and dont have to worry about any piston slap at all. Any insite on that?

I think what they are saying is that you can run a tighter clearance than other forged pistons. They still need .004" clearance vs. the .0015" hypereutectic pistons need. I would ask the exactly what clearance they would recommend. When I purchased my set the recommended a .004" clearance both on paper and over e-mail, as did my machinist. They clearance does close up once the piston is up to temp though.