Kickin’Chicken

Thanks! I appreciate the knowledge shared on this site. Have any of you got advice on whether to “port” my existing head or go with a 7120 head? I’m done swapping TJs and gonna stick it out with this one. So I’m interested in long term fixes for this Rubi. TIA

I have a new project on this Rubicon and forgive me for tacking it on to this thread. The PO threw in a SS header. He bought it but never put it on. I’m thinking about either replacing the head with a 7120(?) and installing the new SS header or installing it on my existing head and enlarging the ports with little grinder bits. I’m also surprised that it only has 3 bolt holes for fastening it to the head. Do the factory exhaust manifolds only have 3 bolts?

On road the engine doesn’t seem as peppy either but I really notice hill climbs and letting it crawl under its own idle. The ‘99 wasn’t as low but seems like it had more torque. Anyway.....my questions centered on the engine performance and not on gearing.

Has anyone tried using a ‘99 motor distributor in place of the coil rail?

It is with 2.73:1 low range but with a 4:1.....4.10 gears are more than enough low.

Does anyone know much about the locking diffs in the ‘04 rubicon? my rear locker Indicator light blinks momentarily then stays lit. The front one just blinks (never stays lit.) They both lock the axles fine but just wondering what the difference is.

4.10:1 in Rubi 4.56 in ‘99 rubi has 4:1 low range ’99 has 2.73:1

36” on both. And I’m not sure of the weight differences but I’ve probably got less weight on this rubi. The ‘99 had a heavy rear bumper/spare tire carrier and a highlift on the hood as well as a warm upright winch with cable. Rubi has stock rear bumper, smittybuilt winch with nylon

Thanks!

as the 4.0 in my old ‘99 Tj. Both have manual transmissions (‘99 had ax15, rubi has nv3550) so that’s pretty even but at low rpm this rubi doesn’t have the umpf that ‘99 had. Did Jeep reduce the exhaust ports or something in the later model 4.0s? Seems like I’ve read that here somewhere. BTW, still working on my MJ. The damn fuel pump isn’t pumping anymore so looks like I’ve got to drop the tank again (thinking seriously about cutting an access hatch in the bed to get to it easier.)

The entire project.

Don’t forget to bring your wallet.

I had an 08 jk 2door with that minivan POS motor. I can’t imagine how weak it was for the 4 door since I never drove one but it was WAY underpowered for my 2door.

There’s talk of them offering a street legal version in the future but in the meantime, buy a cheap CJ7 and a wrecked Roxor and build a diesel cj.......

Not exactly but close! https://www.autoblog.com/2018/03/03/mahindra-roxor-is-an-indian-jeep-built-in-michigan-with-a-diesel/

I'm assuming you've not got it running yet and if so I've got a couple questions: Does the 0331 head use ignition coil packs? If so, how will that work with Renix? Since you're using the 0331 head, why not use the high-flow 0331 "horseshoe" intake?

Dang..... I'm leaning more and more to making the HO plunge.

Love those coils. They look awesome crossed up! What kind and size are they?

Thanks for the info. What work did you do and parts did you replace to fix your idle?

Glad to see that it worked!

Mine isn’t charging so I need one. Is there a better alternator out there, off a dodge maybe, that would be a wise choice?

How many volts are you getting to the distributor?

This one should go for next to nothing..... https://www.copart.com/lot/22403508