Timing Question?

City
Huntsville
State
AL
#1
Took the Scrambler on it's first real trip since the rebuild and have a question and I think it may be timing related. Wanting to get some opinions.

First what I have. The motor is a 4.2 that was rebuilt (shop did the block work and supplied the kit and my brother put it together while I was gone). The carb hasn't been rebuilt yet, it is a Holley 2280. I have set the idle using vacuum. The timing was set with my brother's help, he did it by ear and never used a timing light so I have no real clue advance/retard on the timing. It idles good and runs pretty good. The radiator is a all aluminum 4 core radiator. The Vacuum advance is connected to manifold vacuum.

Around town I've been driving about 20 miles into work each day for awhile now. Good bit of the trip is interstate and usually between 65 to 70 mph. Runs smooth and haven't used the electric fan unless I'm in stop and go traffic at the gate or running the surface roads. Temp stays around 200. Thermostat seems to open at 210 then drop back down. I put a real temp guage in the manifold water jacket and can watch temp changes in real time. Well with the temps rising the past couple of weeks, when it is around 65-75 it has risen to about 205.

On the trip, about half was highway, and the other half while 55-65 mph was windy uphill and downhill. I had two long steep climbs going out that I came down coming back. I was pulling my M-417, but only had some camp chairs, table, and EZup in it. In the Scrambler was my wife and myself, an overnight bag and a cooler. Temps on the Scrambler got up to about 210 going up the long climbs (which were fairly straight). As temps went up oil pressure did drop, but always stayed above 20lbs (direct oil pressure guage, not the stock electric). The first climb I held 55 pretty good in 4th most of the way, and I was between 4th and 3rd on the second as I had traffic in front only doing 40 mph. I felt pretty good about that.

Coming back, there was one windy section that was uphill for a good ways, but didn't seem as steep as the climbs I had done before. It seemed that I lost power going up and barely held 40 in 4th. Temp just barely went over 210.

Why I think it may be timing is that there is a pinging/ticking sound when I'm under load. It happens around town when I accellerate or go up a steep hill, but I've never had it under load for more than a few seconds around town. On the trip with the hills and up and down, I ran into it more often. It seemed that when it was pinging was when the temps tended to go up more. I'm wondering if the timing isn't set right and that is what is causing some heat and power issues under load. Does that sound possible?

Getting a timing light in to check is going to be a bear, there is next to no clearance between the electric fan and the motor. Any suggestions on how to get it on the pulley and how to see the marks would be appreciated.

Thanks!
 

jammer1

Scrambler Junkie
LIFETIME
CJ-8.com Member
City
Maple Hts.
State
Oh
#2
Can you see it from under the jeep. That should be under the fans. May be easier with a helper to turn the distributor. Sounds like it could be timing advanced, fuel low octane,
 

cdvcj8

It's Not My Scrambler
LIFETIME
CJ-8.com Member
City
West Friendship
State
MD
#3
Get a cheap vacuum gauge. Advance to highest reading and then retard it an inch.
 

Roman

Legacy Registered User
City
Kennewick
State
wa
#4
The only answer there is for tuning a 4.2 is JeepHammer...

Mobile right now, so sorry for not posting a link, but I'm sure you or someone else can find his tech info on the Web in seconds.

I grew up in the Era of fuel injection, so carb and distributor tuning was a foreign language and his tech threads not only explain what to do, but also WHY you should do it!
 
City
Huntsville
State
AL
#5
Well, found the timing marks. Thankfully they are set so they can be seen from above and not just from the front like I thought. May have to borrow a timing light to check.

I've never heard of using a vacuum guage for timing. I have one I use to tune the carb wuth. May give that a shot first. cdvcj8, do you disconnect the vacuum advance when doing it that way or leave it connected?

Thanks for the ideas.
 

DirtyB

Crazy Cajun
LIFETIME
CJ-8.com Member
City
Port Allen
State
LA
#6
Get a timing light; that's really the way to do it. Also, if you are going up hill pulling a trailer with a carburated 4.2, I wouldn't expect to go much more than 40 MPH. You might get a little extra using a higher octane, but don't expect much.
 
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