Topic: Time to build it! Got a few questions

[Jeffy]

nevermind, it adjusts the timing offset not the chain. in the end I don't know what's worse, using the plastic tensioner or having one without it like the 6 cylinder, I wish someone would have come up with a better design for the tensioner itself.

There used to be a gear set by Mopar Performance as well.

[sharpxmen]

i could hear the chain vibrating at high rpm, the chain was actually good and the sprockets looked in good shape also, the problem was with the tensioner as the little plastic teeth got worn out and would move up/down - the bracket was polished under the little leg which tells me that was vibrating there like crazy. on the other hand with the no tensioner  design is even worse once the chain or sprockets wear out. I've seen other cars that have an oil pressure fed tensioner which i think it's way better (it is also oiling the chain thru a tiny hole in there)

[grumpygy]

Harley up till 2007 had a spring tension Tensioner. The spring was a monster spring and it ate the shoes right up only got about 30,000 miles out of it.  So last year I changed mine over to what the 2007 has which is tension by oil pressure.  But I also had to change out the oil pump cause mine was too low of pressure.

[dwtaylorpdx]

How does it perform with the RVOB cam? The cam I'm looking at is similar to it. I'm also interested in the adjustable timing set, got any info on it?
Al

It gives you back a gear.. IN my case anyway. I have a long long steep hill that before the rebuild I could never pull in 5th, and barely in 4th..
It now pulls easily in 4th and as long as I hit the hill at 50 will pull it 55+ over the top in 5th.

Oh and I forgot the 4.0 throttle body with spacer in the list.. :) The IDLE of the RVOB is nice, you can tell its not the stock cam but only if you are used to the sound of the 2.5, I also have a 2.5inch exhaust, Clifford Tri-Y Header, and a Spintech muffler.. Above 3000 there is NO doubt something is different. It snarls. 

With my rebuild I can pull 6000 rpm with no issues.. But my fuel curve has never been "right" the stock ECU does not handle the increased air flow and tends to run rich in the mid range and lean out up on top.

I finally acquired a wide-band and a data logger so hopefully this spring I'll finally figure out if its just the ECU or some sender tweaking things..

Cant remember the exact degrees my engine builder dialed the cam in at , but we didn't use the most aggressive setting as I have to pass emissions and we were afraid full timing would have prevented that. That's another thing the wide band will help with.

Dave

[dwtaylorpdx]

FYI I have over 70K on my rebuild and the 4.0 chainset is still nice and tight without a tensioner..

Dave

[sharpxmen]

FYI I have over 70K on my rebuild and the 4.0 chainset is still nice and tight without a tensioner..

Dave

i might bite the bullet and get one when i rebuild mine, seeme a lot better setup than the plastic pieces with the other one (which by the time you actually need it is worn out anyway).

[bigal389]

Ok here's a quick update: I pulled the head off my 2.5 last night after doing a compression check which failed miserably, I really don't see how it was even running, the cylinder with the highest comp. only had 87 psi. Any yes I thought my gauge was off so I borrowed another one, they were within 2 psi. This was done with the throttle open wet and dry. Wet gained 5 psi.
After pulling the head it was obvious why there was ok compression. It was already .060 over and had  a .020 wear ring around tops or the cylinders. So I found a 2000 model engine with a fresh rebuild, wiring harness, all sensors, acc. and ecu for a very good price. How difficult will it be to do this mpfi with obd2 into an 87?
Thanks Al

[sharpxmen]

hmm, i've heard of tbi models converted to 91-95 (basically the entire engine and cab harness replaced along with the speedo/tach and gauge clusters. It can be done but you will need to solve your instruments/dash lights as well. On top of that you would also need the fuel pump  assembly installed in your tank, on TJs is a returnless system running at 49psi, yours is something like 20psi (i can't remember exactly but it's low even compared to YJ).

the other option you have is to just replace the engine and keep your existing fuel injection, senders, distributor, intake/exhaust and accessories (alternator, power/steering, etc) which i think would be a lot easier and with less headaches.

[bigal389]

Yeah I was thinking the same thing it would be a lot less trouble to swap the tbi stuff over to the new engine and just add the cam and roller rockers for now.
Al

[sharpxmen]

only thing i'd worry about with your tbi is the size of the t/b. Other thing that i'd research is if you can delete the EGR (with a block off plate).
One thing to mention is for the TJ motor you'll have to drill a hole in the head for the temp sender for the water temp gauge or drill one in the thermostat housing and extend the wire, TJ only has one temp sender for the PCM in the thermostat housing and the gauge is driven by the PCM and not measuring directly from the sender as with the YJ.

[bigal389]

I think I'll need to swap the intake to the tbi intake. Will doing an egr delete hurt anything on the tbi engine? What size hole do I need to drill and tap for the temp sender?
Thanks, Al

[sharpxmen]

I think I'll need to swap the intake to the tbi intake. Will doing an egr delete hurt anything on the tbi engine? What size hole do I need to drill and tap for the temp sender?
Thanks, Al

thread is 1/8'' NPT for the temp sender (standard size for these)

I don't know about the EGR, i've seen it on other cars but don't recall hearing or reading about it for the YJ TBI (91+ does not have egr including TJs).

[chardrc]

I thought i had heard of someone having had done an egr delete on a tbi yj on here but never went into details. it would be simple to just make a plate to bock the port on the intake manifold and another to plug the exhaust manifold port (or use the TJ exhaust manifold). the question would be if the ecm would figure out that the egr isn't working or if it would  end up leaning out the mixture when it thinks exhaust gas is being added.

found the thread: http://4bangerjp.com/forums/index.php/topic,9553.msg81610.html#msg81610

the user didn't go into much detail and did a pretty extensive change of retrofitting the tbi system to a mpfi manifold. haven't heard anything from the user in years so don't have a good feel on the longevity....

[sharpxmen]

mixture would be based on O2 closed loop, in open loop EGR should be off anyway (even until it warms up).

[chardrc]

mixture would be based on O2 closed loop, in open loop EGR should be off anyway (even until it warms up).

your right, forgot that egr is only used in closed loop.