86 Jeep v6 (2.8)

[labattconsumer]

I know this has probably been discussed a thousand times and I apologize for not being able to find the info, but I'm pressed for time and "Damn this dial-up anyway!". I need to get my Jeep movin' this week and I'm having problems getting it to fire. Let me start by giving all the info I can on what has been done and the problems I'm noticing.

1) Engine is a complete rebuild bought online from S&S Rebuilds out of Spokane Washington. It is warranted for the original 7 year/70,000 miles, so I feel they probably did a good job.

2) I had to adjust the valve lash and I went by the Haynes manual I have. It states that I am to find TDC on #1 and adjust in sequence. It states that I'm to tighten the rocker nut until drag is felt on the pushrod, then tighten 1-1/2 turns. Since I did not know this until after I put the intake manifold on, I used the "jiggling" of the rocker as the factor. Once the rocker didn't "jiggle" I tightened the nut 1-1/2 turns. Could I have overtightened them?

3) I notice no obvious compression when I remove the #1 spark plug and crank the motor. Is this due to the valves being overtightened?

4) I get fuel to the carb and it backfires through the carb while trying to start. When I pulled the plugs, I noticed no gas or moisture. Why?

5) I know the timing is correct because I've been over this thing for the past week now. I've triple checked most of everything I can think of besides the valves (simply because it's such a bitch to remove the covers).

I would like some info asap. My mind is completely raced out at this time. I would like some info on how to route my vacuum lines as well. I have almost all of them figured out but there is a stragler that I cannot find a home for. Any links with diagrams for the "home mechanic" would be greatly appreciated.

You can email me direct at [email protected] since I rarely surf the net. My wife and I have a 20 month old son and were just "blessed" with twin boys in January! So, needless to say, time is not on my side for internet and mechanic work.

Thanks again...

[JDPascal]

Hi labattcomsumer. I just read your post about you engine problems and I sympathise with your situation.

If the engine you put in was a complete rebuild with heads already installed, I am not sure why you would need to adjust the valves.

New valve lifters do not lend themselves to adjustment very well after the engine has been pressured up like it might have depending on the rebuilders quality test methods.

From what you say about back firing, it sounds like you are getting fuel and spark but the valves are being held open.

I would suggest that you back off the valve adjustment a ¼ turn at a time on all the valves until the engine runs. My personal preference is to use a 1 turn adjustment for the lifters and let the expansion of the parts take care of the remaining ½ turn to position the plunger in the lifter but either way, right now the valves would seem to be held open – hence no compression.

Since you are on line now I will post this in the thread you started and also email it to you..

Don’t hesitate to email me back with any questions.

JD

[labattconsumer]

I pulled the valve covers, removed the plugs, backed off the rocker nuts and turned over the motor.

Guess what?

I've got compression now....and four bent rods. Yippee! #1,#3,#5 and #6 exhaust rods are wickedly bent.

I'm going to replace them and need to know if there is anything in particular that I need to watch for. My dad mentioned something about "keepers falling out of place" or something to that effect. Would it hurt to use the rods out of the old motor as long as they are cleaned well?

[xj31]

The rods you bent,I assume you mean the pushrods.You should have no problem using old ones but you might have other issues now.Basically,if you bent them there is a reason why they bent.And if you had the rocker arms too tight then they probably bent because the valves were pushed open too far and were hit by the pistons.Usually when valves meet pistons it is not a good thing.So there is a good possibility that you bent some valves also.This might not keep the engine from starting and running but if the valves are bent just a little you might experience a misfire especially at idle so if you get it running but it idles like garbage,the valves are probably bent.

[labattconsumer]

Great!

Just what I needed.

[MagicRat]

Excellent advice in this thread.
IMHO use some old pushrods, if they are straight and the round ends are smooth.

Likely if your cam timing is correct, the pushrods just compressed the valve springs all the way, but the valves (hopefully ) did not hit the pistons.
If the exhaust valves are bent, as posted above, the idle will be rough.

If you can get it to idle reasonably smoothly, just drive it. I'll likely be okay.