Some misc ?.. cam chioce and piston rings

[SilverXJ]

I'm trying to get parts together for my 2000 XJ 4.6L stroker. 4.2L crank, KB944s, 4.0l rods, 4.0l block, ported and polished head. Compression ratio looks like 9.6 static with 0 deck clearance and .051" headgasket. Shooting for 86 octane gas.

I'm looking at cam choices.. I have ran the CompCam 68-231-4 cam in the past with good results. And other recommendations? This is a daily driver, will see some light towing, some light offroad, but streetability is most important. Also, longevity of the cam is a priority.

Also, the piston rings that come with the KB944s are moly. Any reason to go with something else?

Also, those of you than have used the KB944 pistons how do you like them? How bad is the cold piston slap? What clearances did you go with?

I think I have most everything figures out aside from where to get the crank and rods.

[John]

I'm trying to get parts together for my 2000 XJ 4.6L stroker. 4.2L crank, KB944s, 4.0l rods, 4.0l block, ported and polished head.

I'm looking at cam choices.. I have ran the CompCam 68-231-4 cam in the past with good results. And other recommendations? This is a daily driver, will see some light towing, some light offroad, but streetability is most important. Also, longevity of the cam is a priority.

Also, the piston rings that come with the KB944s are moly. Any reason to go with something else?

Also, those of you than have used the KB944 pistons how do you like them? How bad is the cold piston slap? What clearances did you go with?

I think I have most everything figures out aside from where to get the crank and rods.

1. Compression ratio looks like 9.6 static with 0 deck clearance and .051" headgasket. Shooting for 86 octane gas. With that increase in compression dynamic compression needs to be considered if you want to run on 86 octane. Cam life is likely in your hands with oil, valve spring, valve geometry, lifter quality and break in procedure being your controls. We have many more successful builds than early failures to discuss. I worked with this design of motors for 35 years and the failures are more often as not traced to one or more of the above items.

2.I am a fan of the 68-231-4 and one lives in my 94 YJ, Also look at the Hesco selection.

3.Moly rings that came with the pistons, use them.

4. Havent used these yet.

John

[SilverXJ]

For valve springs I am running the mopar performance units set at 100# seat load. Cam break in I am more fully aware of so that is taken care of. Also have Harland sharp roller rockers. As for the lifters I don't know. I've used both compcams and Crower camsaver lifters. While I liked the idea of the camsaver feature I thought the compcams had a better finish. Don't know how much that means or not. I also think (not sure though) that the compcam lifters can be had with a cam oiling hole. If I do go with the 68-231-4 I will get it nitrited(sp) by them.

[John]

Sounds like the spring selection is good, cam break in covered, nitriding cams and cranks ( you said cam I know, but this is a old rant for me) is always good if done well. Roller rockers are a great heat reducer for your motor oil. I would personally go with degree of finish on the foot of the lifter and any method of getting additional quantities of today's or tomorrows motor oils to the cam/lifter area is only responsible design. Yesterdays oils, Mopar's jeep engines described the lubrication "adequate" for as built engines, you are going beyond that.
John

[1bolt]

First let me be honest and mention that I am no cam guru, as we talked about when you picked up the block. But having played with 3 different RV cams (HESCO RVOB and 2 Cliffords), versus a couple Comp cams that were about higher peake HP and streetable power, and most of the OEM cams... For my 2 cents there's negligible difference on a mild build between the HP oriented aftermarket cams and the OEM's... If you're building something wild that would actually see some passes at the strip, some nitrous or something its a different story, but safe to say your DD probably isn't going to double as a quarter miler.

If you want to feel like you installed something that was worth the added expense, and you want there to be no mistake about it every time you goose the pedal. Then go with a low torque RV cam.

Just my opinion, also seems to help with the MPG. A 2500 to 3500 torque peak is really close to your cruising hiway speed which most of us probably do around 2000-2500 RPM's as oposed to the 3900 or higher torque peak you'll find with most HP cams. If your RV cam gives you an extra 35 foot pounds at 2500 RPM (Not to be confused with a total peak torque gain of 35 just 35 more at THAT RPM, that's a lot more muscle to push the aero brick through the wind.

[SilverXJ]

Brain fart... static compression is 9.45