timing Problems

[mowr]

The other day I was driving down the road and my engine died (small pop). I pulled the distributor and the gear was all chewed up. A year ago
I had a mechanic do a tune up, and he didn't get the dist. in all the way. It chewed up the cam gear, bent the dist. shaft and ate the gear (he replaced the dist.). Anyway I set the engine (86 360) TDC #1 cyl. on compression stroke, pulled the valve cover to check valves (#1 closed) and dist. was off, either on #2 or #8 cyl. I put in another dist. set to #1 cyl. and it ran great until the next backfire. The engine has 160,000 miles on it and I'd like to nail down if this might be my timing chain jumping. I'd like to run this engine until I can finish another Jeep. Also I read on here that unmatchd cam and dist. gears will eat each other, what can be done about this?

[jeepfan93]

A matched set of gears from another truck or new. Check the chain, make sure the oil hole is lined up.

[Gadzooks2]

There is a whole other thread on this subject. I had this problem and replaced timing gears and cam/dist. gears only to have it chew up again at about 100 miles. Found out there are some new cam gears on the market with partially pluged or not lined up oil holes. I had got one of them. Drilled out the next set, but that didn't live either. New bronze dist. gear and cam gear. That died too.

I hate to be a buzz kill, but I'm afraid youre in for a rough go. Maybe cam bearings? but that makes no sense either since the angle of the gears push the cam towards the back of the block anyway and the oil pressure would be real low?

Good luck and if you find something that fixes it positively, please post it because a lot people have had this same issue.:banghead:

[mowr]

I pulled the timing cover today, and found alot of slack in the chain. The cam gear and the dist. gear are both shot. What realy worries me though is the .035 end play in the cam shaft. From what little reference I have found on this, end play should be 0". Does anyone know if this is correct?
Is my engine just plain wore out or is there a bandaid for this?

[jeepfan93]

Actually, I discovered that when I put the new cam in my 360. That much endplay is normal. I talked to Ristow on it and he confirmed. Absolutly normal. When you put it together, the dizzy and front cover will hold it in place. I put mine together a while ago and all is fine. Now if you put it togther and still have the end play problem then you've got a problem. Way to check is to pull the intake then get down through the top of the motor and check it

[JeepNOFEAR]

I had the same problem, never have heard a backfire loader than that. After 3 times of replacing the cam gear I got another motor. I had done everything, even had an oil line spraying oil right on the gear. That made it last alittle longer.

Good luck!

[Poley]

had the same problem about 1.5 years ago sucked

[Ristow]

when the engine is running,the cam is pushed back into the block from the resistance offered by the oil pump and distributor,using the rear of the cam sprocket as the thrust bearing.

look closely at the condition of the bottom bushing of the distributor.

[Crazy_Jeepman]

I think if you look at an AMC cam you will see that the lobes are ground at an angle, so that the pressures developed by the valvetrain keep the cam centered in the block. Lifter wear/cam wear decrease this angle, as does clattering lifters from poor oil pressure once these conditions become present the cam can then take a WALK ;)

[Ristow]

all typical american V8's have the lobes ground at a slight angle so the lifters rotate as the lobe lifts them.i don't believe that helps locate the cam,as the lifters are pushing straight down on the lobe,just not on the center.that is simply my thought on the subject,i'm certainly not an authority on the subject.

i do know the oil pump offers a substantial amount of resistance to turn,and that load is placed on the cam gear,pushing it back into the block,against the back of the cam gear.