RenixXJ87

Got an 87 XJ with the 4.0L and BA 10/5. The motor is dying on the vine - you can hear the lifters and it's misfiring on occasion. My buddy's friend has a rolled 98 with 60,000 on the motor.

I have read cruiser54's HO Into a Renix Swap extensively and it sounds pretty doable. I've decided to keep the Renix setup and reuse the intake, but I still want to upgrade a few things and I wanted to see if it made sense.

1) Decided NOT to extrude hone or port the intake manifold as the old log style intake manifold will probably make no difference at all and be a waste of money.

2) Want to replace the injectors with bigger ones. Was thinking 21 lb-hr. Does this sound right? Bigger?

3) Want to send in throttle body and have it over bored to 60 mm.

4) What is best aftermarket gasket for intake and exhaust manifold. Any metal layer sandwich type deals out there or just use fel-pro?

5) Replace all sensors.

Does this sound like a logical plan of action? General thoughts and comments appreciated.

Crazy 8s

1) Decided NOT to extrude hone or port the intake manifold as the old log style intake manifold will probably make no difference at all and be a waste of money.

---extrude honing and port matching would actually create a more powerful, better running motor. If you have easy access to such and don't mind spending a little bit of $ you might do this anyway. With your hopes to bore out the TB it seems like you are interested in a bit more power...

2) Want to replace the injectors with bigger ones. Was thinking 21 lb-hr. Does this sound right? Bigger?

---bigger may not be better, but a more efficient 4-nozzle injector would be. There are sets of reconditioned injectors being offered by a couple forum members that other folks here speak very highly of...and for about $100 a set. I don't recall the names of the folks who offer these injectors, but I am sure some will speak up and say soon. Ebay has them too...

3) Want to send in throttle body and have it over bored to 60 mm.

---there is another member here who can bore that out for you too, yet again I don't recall their name. My thoughts are that you should try to work in the '98s intake because it is better all around anyway and wouldn't need much modification to get working with RENIX sensors. 62mm TBs are commonly available on ebay for about $100.

4) What is best aftermarket gasket for intake and exhaust manifold. Any metal layer sandwich type deals out there or just use fel-pro?

---Fel-pro would be as good as anything else or better...

5) Replace all sensors.

---if you got the money to do so, go for it. Personally, I would reuse the ones I had that worked cus money is an issue in my case. New sensors can be DOA and that would make troubleshooting any problems way more challenging because the assumption of it being new is that it should work when it may not... If you know the sensor is working, you should use it.

Fred/N0AZZ

Cruiser will give you the best answers for these questions a few I can help on.

Injector upgrade you might consider a 4 hole one from a later model Programbo sells them here that are rebuilt and very nice, made a difference in mine. A seller here on the board sells bored TB's for about $90 shipped and he does give you a core charge if you return yours. Excellent job on the TB and I do have one of his also.

At least with these 2 sellers they are here all the time and not on just eBay where you know of no one who uses that product.

RenixXJ87

---extrude honing and port matching would actually create a more powerful, better running motor. If you have easy access to such and don't mind spending a little bit of $ you might do this anyway. With your hopes to bore out the TB it seems like you are interested in a bit more power...

OK so my mechanic tells me that what they found back in the day when people port and polished their intake manifolds is that "zones" were created in the intake. As in you would get a "gas zone" and an "air zone" and it didn't mix and run as efficiently. In fact the burrs and imperfections in the intake manifold helped to mix up the gas and air; thus producing a better running engine. I'm not trying to pretend I know, but the old Renix intake manifold is not exactly setup for awesome airflow - hence the redesign in 1991. Anyone else try extrude honing or porting their Renix head. Please let me know if it gave results worthy of justifying spending the money.

cruiser54

Felpro gasket is fine.

Port matching is worth it. Done it multiple times. Match to the Renix gasket. You can do it yourself. No need to extrude hone anything.

www.strokedjeep.com has the 60mm Renix throttle bodies.

0 280 155 746 injectors from Programbo.

A high altitude CPS from RockAuto part number PC307. Drill the upper hole per Tip 7.

Be sure to index the distributor. Tips 12 and 13. Use NGK plugs and Taylor wires.

cruiser54

Forgot I had this: