Stock or CompCam? What kind of performance difference?

[Brandon_K]

So I've been fighting my way through this build, I'm simply not as prepared as I had thought and to further add to it, I'm in a serious time crunch to get this back together, it is my daily driver after all and I head out of town with it in less than 2 weeks. I still have some suspension items to fix, a new driveshaft to be made, etc so I can't focus all of the 2 weeks on the motor.

Anyhow..

I've come to find out that the CC 68-231-4 is old style, after searching for what I need to do to make it work with my 99 block, I've come across all of these posts about cam / lifter failure. I also don't have the right parts (258 timing set, pin, spring, bolt, etc) to get it back together as it sits, unless I reuse the old cam.

What kind of performance decrease are we talking if I just reuse the old stock 4.0 cam? I've ran the numbers in the CRC and with the 68-231-4 I get a SCR of 9.82 and a DCR of 8.63. If I use the OE cam I get a DCR of 8.16. I'd like to run midgrade, so a lower DCR is going to help me here, but at what cost? If it matters, my quench is .0665.

Being my first build I'm double guessing myself left and right. I'm more concerned about reliability than performance. I don't want to be pulling the motor in 2 years after 30k to replace lifters or a cam shaft to gain 10ft lb now, I would also like to get better economy as well. The one post I read regarding this said he didn't notice any difference in SOTP dyno going back to a OE cam plus his mileage went up. Another for what it's worth, it will be broken in with Brad Penn Break In and I plan to continue running Brad Penn 10/30.

[edit] Also, I already have the MP springs with the 8 degree retainers and locks installed on the (bolted to the block) head. Can I use the MP springs with the OE cam or is it going to be to much pressure? I'll need to get a new set of OE springs if I end up running the OE cam [/edit]

Halp. Again.

[gradon]

My 4.6 has a scr of 10:1, dcr of 8.57:1 and quench of .062-3". 8.5:1dcr is on the edge of being able to use pump gas--93 octane. I read about this when I was building it and knew to shoot for 8.2:1 or 8.4 at most to give some room for tolerance differences(I was originally gonna do the 4.0 rod and KBs, but they weren't available at the time). Mine lightly pings due to that high comp(it will be fixed in the near future). Now will an engine with the same dcr, but quench that is .020" less(zero deck and .043" HG) be less likely to ping? I would recommend if you go with the CompCam to get your pistons dished as much as possible and to deck your block to get the best quench and hopefully the dcr will be in the lower 8s, then you can start thinking about mid-grade.

[Brandon_K]

Thanks for the reply. At this point, I'm just going to put the stock cam back in it. It's not going to breath as well and I'm going to lose power, but the 4.6 is going to be a huge gain over the original 4.0, stock cam or not.

I'm out of time, nearly out of coin and out of patience, so stock cam it be. I think I'm going to run to the parts store and put the calipers on a Felpro head gasket. The MLS Victor headgasket that I already put on it seems wicked thick and I know it's not helping my quench.

[Muad'Dib]

The Victor Reinz MLS is .043 compressed. Its a good gasket. The felpro is probably going to be stock at .051.

[Brandon_K]

Thanks for the replies gents.

I put the motor back together with the stock cam, it's fully dressed, oil pump is primed, ready to be installed back into the TJ. The VicReinz gasket set came with a gasket for the 99+ 4.0L's which is what I have, but I apparently have a mid year build as I have the "old" head with the lower deck, back to the parts store to get the right manifold gasket, it's one thing after another I suppose. As soon as I get home from work tomorrow I'll be dropping it in. Between the harness, AC lines, power steering, etc as well as having to install the new trans (AX15 was shot, replaced with a NV3550) and clutch, I doubt I'll get it started tomorrow. Even if I got all of it put back in, it will be to late in the evening to actually run it (open cat, haven't decided on a cat back system yet) as she sits outside in a 12x26 "portable garage". Then a new set of adjustable UCA's and a new CV driveshaft and I'll actually be able to drive it again!

I'll update when she gets to running. I've learned an immense amount doing this build. This is the first motor I've built myself and I would certainly do a lot of things different on another stroker build. Checking to make sure all of the parts work together would be a start

[stroked'73]

Where did you end up getting the MP springs/retainers?

When Dino's cam bought the farm, he put the stock one back in and reported little difference.

[Brandon_K]

Stroked, sorry for the late reply, have been busy. The locks came from ChicagoConnection.com (AWESOME service). The springs and retainers came from Jegs, they price matched O'Reilys.