Hello again. Just crawled out from under this beast. For the past few days I've been throwing things back together. Got the 2.8 heads back Wednesday, set them Thursday morning. Got all the other stuff on yesterday and last night. Figured out the vaccum hose madness this morning. Test drive went well cept for some minor bugs to work out. One question I had for the 3.4 wizards in the bunch; When setting the timing, using the marks from the 2.8, I had to set in on 8-9 deg. Attempting to set in on 0 only killed the engine. I am using the 2.8 timing scale and damper/balancer. Would the timing marks on the 3.4 damper/balancer differ from those on the 2.8? Do you guys set it to feel or is there a number you settle with? It surges just a little, but runs bloody good when taching at 2500 - 3000. I feel that the surge does get better once warmed up. I am still using my 2.8 TBI and have not bored the intake. Also, I do have a 4.3 TBI to use, but it was spraying waaay too much petro so I swapped the 2.8 TBI back on. As soon as I find the source of a minor oil leak and can set the timing set correctly, I can call my baby roadworthy again. Later I'll start working on trailworthy. <img src="/forums/images/graemlins/notooth.gif" alt="" /> Thanks,

JC

Well, not sure why you'd set it at Zero when the spec is 10 deg BTDC !! <img src="/forums/images/graemlins/pfft.gif" alt="" />

You'll find that it'll run pretty good with about 13-15 deg of advance vice the stock 10. How much it'll tolerate is dependant on the quality of fuel in your area. The knock sensor circuit should allow a trace amount of pinging under initial throttle tip-in with light loads and also when lugging the motor but you shouldn't get a lot of pinging. If you do, back off a few degrees and see how that works.

I wouldn't think that the marks on the 3.4 balancer would be any different from the 2.8's but I can't recall without looking at one. You'd have to compare the relation of the dampers' marks to the crankshaft keyway slot in the damper. I'm assuming you used the 2.8 timing cover in order to have a useable timing scale.

To be able to see the timing marks and accurately adjust spark advance you'll need to disconnect the Electronic Spark Control (ESC) wire in the middle console. Just pull out the little tray in the front of the console and you should see a white wire with black stripe. If the color differs, no matter, the ESC is the only wire in the console area that has an inline bullet connector. To disable the ESC circuit you'll unplug the wire from itself. This will remove any 'artificial' timing advance which the ESC circuit imposes at idle.

Disconnecting the ESC wire will also cause the 'check engine' lite to come on, but it'll clear once the wire is reconnected.

So, unplug the ESC wire, check and adjust your timing, (have fun with the distributor holddown bolt!!), reconnect the wire, and I expect she'll run a lot better.

BTW your computer will adjust to the new motor so it may take a while before it runs real sharp. But you should immediately notice the improvement over a stock 2.8!

Let us know how it runs...........ed

Thanks for the reply ed. That did help. I got the timing figured out, mostly with the addition of the 4.3 injectors and a little fun with the distributor bolt. Holds a steady idle at 1000 rpm., timing set at 16 BTDC. Runs great. Feels better than it ever has, in the last 6 years of driving it. Got all that figured out only to hear another noise that is disturbing beyond my comprehension at this point. The 3.4 has a rod knocking. This is precisely what the 2.8 was doing, exact same noise, which prompted the 3.4 swap to begin with. My frustration at this point is overwhelming. All I can think to do is a write-up about how to avoid this for anyone else thinking about any kind of engine swap. Just a few pointers of "WHAT NOT TO DO". Maybe in all of this I can share something that may help someone. When my anger (at myself) settles I would like to share some pointers, sometime. Thanks for all the help. Is it possible to remove the oilpan without pulling the engine? Looks like the entire front suspension needs to be removed to get the axle off. Am I delusional that this is possible? <img src="/forums/images/graemlins/confused.gif" alt="" />

JC

That's a real bummer Dude!!! <img src="/forums/images/graemlins/angry.gif" alt="" />

I'm wondering if you have an auto tranny, if so, you may have a cracked flex plate which is causing the knocking. Especially considering the old motor had the same noise. A cracked flex plate can sound just like rod knock.

One way to diagnose a knocking rod is to undo plug wires one at a time and when you kill spark on the offending cylinder, the knocking should go away.

How's your oil pressure, does it come right up and stick around 50 psig+, or is it slow to rise and a low value??

What's the supposed history of this motor and what did it look like inside when you had the oil pan and intake pulled? My 3.4 was spotless inside and that made me very happy!

I'm thinking (as terrible the thought may be) that it's probably easier to pull the motor back out. Don't think you'd have much fun at all trying to drop the entire front suspension for access to the oil pan.

One thing that I found made it easier was undoing the (4) very large bolts (2 per side) that hold the diff/axle assy to the frame. This allows the assy to drop down a bit and makes more room for the oil pan to clear. Also, removing the motor mounts altogether gives you more room to move the motor around.

I'm curious, did you do a Post-Mortem on the 2.8; did the main or rod bearings show signs of great distress? When I tore apart the <just-starting-to-knock> 2.8 in my '89 "stroker project" Trooper, the rod bearings were pretty wiped and the rear/thrust mn brgs were totalled. This one had deteriorated intake manifold gaskets and antifreeze in the coolant, guaranteed to eat up bearings!

HTH, keep us posted..........ed