Jeep Enthusiast Forums banner

Issues after camshaft install

1K views 18 replies 6 participants last post by  manest 
#1 ·
Ok guys, I need your help.

Here's the gig. Working on my 93 YJ 4.0. Yesterday I finished up the installation of my new stock cam, lifters and timing set. After everything was back together I started it up the first time to begin camshaft break-in. Upon initial startup, it seemed to struggle to fire, but that is normal after such a job. I ran the engine for 30 minutes between 1500 and 2000 RPM as directed per the cam instructions.During this time, it felt as if I went over 2000 rpm, it was struggling. I shut it down and changed the oil and filter. Jumped back inside and went to start it and all it did was crank over with a few half hearted fires. I gave it some gas and it would spit and sputter a bit. I continued cranking and varied the throttle and it was firing more and more until it stumbled and took off. When running, the throttle felt soggy and I could tell it wasn't running right. I thought maybe I had the distributor a tooth retarded, as there was NO backfiring or any of the other symptoms I would get with an advanced timing. I put the motor to 0 degrees firing TDC and pulled the cap. The rotor pointed directly at #1. I thought and thought to myself and then convinced myself that I must have botched the timing chain timing and that was the issue. I tore the front of the motor back down to verify. Rolled it around and the timing dots line up perfectly.

The jeep ran and started perfectly before the camshaft job. Only reason I changed it was due to a sticky lifter that liked to tick all day.

Fuel pressure checked and verified within spec with a gauge.

The only thing else I changed was the spark plugs. I installed Autolite Platinum AP985 spark plugs.

When I pull a plug, its dry, no sign of flooding.

Verified all engine electrical connections, double checking nothing was missed during assembly.

What do you think happened?
 
See less See more
#7 ·
I thought maybe I had the distributor a tooth retarded, as there was NO backfiring or any of the other symptoms I would get with an advanced timing. I put the motor to 0 degrees firing TDC and pulled the cap. The rotor pointed directly at #1.
It does sound like the timing is retarded. The rotor should line up just past the #1 post if the crank is at TDC 0* and be pointed to the 5 o'clock position.

see this thread: http://www.jeepforum.com/forum/f12/distributor-removal-installation-4-0l-2-5l-1173859/
 
#10 ·
Ok, to answer all of your questions... I never removed the intake from the head when I pulled the head. I double checked my vacuum lines and all are connected properly.

I'm doubtful it has thrown a code as the check engine light has not come on. Once I get the timing cover back on and the engine running, I will check for a code anyways.

I changed the timing chain and gear set at the same time as the camshaft. I also suspected a timing issue, this is why I pulled the timing cover back off to verify. Dots line up perfectly.

The distributor rotor was pointing directly at the #1 on the distributor cap.

It is not nuttered. That only applies to the non-fuel injected 4.0 engine

Sorry, I dont know how to do the whole quote thing in the forums. Maybe someday ill figure it out.
I'm heading out to the shop after this message to start the re-assembly. Ill keep an eye on this thread as I go along.
 
#12 ·
#16 ·
The distributor is correctly installed when:

•rotor is pointed at 5 o'clock position (4.0L engine)
•plastic alignment pin (or pin punch tool) is still installed to distributor.
•number 1 cylinder piston is set at top dead center (TDC) (compression stroke)
•centerline of slot at base of distributor is aligned to centerline of distributor holddown bolt hole on engine. In this position, the holddown bolt should easily pass through slot and into engine.

Pull your cam sensor (plate below the rotor) and check the alignment pin holes for alignment.
 
#15 ·
OK, I pulled the dizzy out and followed the instructions using the pin method. I set the distributor back in and I was surprised at how far passed the rotor was in relation to the #1 on the cap. Gave it a shot and it started. Going to let it run a bit and maybe a test drive and I'll report back.
 
#18 ·
Took it for a 2 minute drive and it seems to run decent. Starts fine. The RPM's dropped quite low when I put the clutch in to turn into my driveway. It feels to me like the distributor needs some fine tuning, however with the locking ears on the base, that's not possible. I cant believe it runs with the rotor tab so far passed the #1 cap post. It was not like that upon disassembly. The yellow line I marked on the distributor is where the rotor tab was located prior to pulling the distributor out. Any idea what the deal is?
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top