Posted By: dustergirl340
Tooth off on timing chain?........ - 08/17/09 01:00 AM
What would be the symptoms of a timing chain being one tooth off? This is on a 360.
Tooth off on timing chain?........
Posted By: aarcuda
Re: Tooth off on timing chain?........ - 08/17/09 01:04 AM
loss of power. hard to start. runs like junk
Posted By: RapidRobert
Re: Tooth off on timing chain?........ - 08/17/09 01:26 AM
put your marks on TDC & see where the rotor is (whether #1 or #6) it'll be way off from the underside of the dist cap terminal. More details, what happened.
Posted By: dustergirl340
Re: Tooth off on timing chain?........ - 08/17/09 01:53 AM
Quote:
put your marks on TDC & see where the rotor is (whether #1 or #6) it'll be way off from the underside of the dist cap terminal. More details, what happened.
Already done.
We set the timing at 35* at 3,000 rpm. It has very low vacuum (9"). But if you advance the timing to 42* we can get the vacuum up to 17".
Engine has a miss between 1,800 to 2,300 rpm. The engine runs better with a lot of advance but still has that stutter.
We've ruled out vacuum leaks.
Posted By: Anonymous
Re: Tooth off on timing chain?........ - 08/17/09 01:53 AM
I think if you pull the fuel pump you can feel for the slop in the chain. Does this maybe have the phenolic top sprocket? If steel, there's very little chance that it's slipped.
Quickest way, is that IF you know where the timing is supposed to be, and it's way off, it's slipped.
Take a wrench and rotate the engine cw/ ccw against the chain "slop." If it's 10* movement or more, I'd be suspecting slippage.
Quickest way, is that IF you know where the timing is supposed to be, and it's way off, it's slipped.
Take a wrench and rotate the engine cw/ ccw against the chain "slop." If it's 10* movement or more, I'd be suspecting slippage.
Posted By: RapidRobert
Re: Tooth off on timing chain?........ - 08/17/09 02:00 AM
Quote:and where was the rotor
Already done.
Posted By: MoparforLife
Re: Tooth off on timing chain?........ - 08/17/09 02:28 AM
Is this a new installed timing set, or what are we working on? In all the years of working on this stuff about the only time I have seen a timing chain off a tooth is if it were installed that way. It can happen but the vast majority of the time if a chain goes south it is is because it is running on the plastic sprocket and the sprocket teeth go away and the chain literally spins on the sprocket. When this happens you will have not so cute little eye brows on the pistons very likely along with some bent valves.
Posted By: Alaskan_TA
Re: Tooth off on timing chain?........ - 08/17/09 02:28 AM
Pull the distributor cap.
Rotate the crankshaft back & forth with a socket wrench while watching the rotor.
If the timing chain is worn, you will be able to move the crank a few degrees without seeing the rotor move.
If they do not move together, replace the chain & gears.
Rotate the crankshaft back & forth with a socket wrench while watching the rotor.
If the timing chain is worn, you will be able to move the crank a few degrees without seeing the rotor move.
If they do not move together, replace the chain & gears.
Posted By: dustergirl340
Re: Tooth off on timing chain?........ - 08/17/09 01:31 PM
just checked, the timing chain (new chain) is dead on. Harmonic balancer is good (didn't slip). Back fires out the carb at rapid throttle and has steady 9" of vacuum with timing set at 35 degrees at 3000. Now if we set the timing to 45 degree the vacuum is at steady 17" no popping out of the carb and the engine seems to run fine except for a miss between 1800 to 2300 RPM.Rotor points to #1 wire. Compression test is normal.
Posted By: buildanother
Re: Tooth off on timing chain?........ - 08/17/09 01:39 PM
Sounds like you may need to add initial timing and limit the extent of the full advance. Or is the advance locked out already? 
Posted By: RapidRobert
Re: Tooth off on timing chain?........ - 08/17/09 01:56 PM
Quote:
Sounds like you may need to add initial timing and limit the extent of the full advance.
. I'd set the initial (vac gauge method) then weld (no JB 
) the slots for 35 total (w vac adv disconnected) then ch the springs staying just under the pinging point @ WOT then plugging in the vac adv (if used) & adj for just under the pinging point at part throttle
Posted By: marvo451
Re: Tooth off on timing chain?........ - 08/17/09 02:35 PM
Are you sure the harmonic balancer hasn't slipped on its rubber ring, giving you incorrect timing with the timing light?
Posted By: MoparforLife
Re: Tooth off on timing chain?........ - 08/17/09 03:53 PM
Make sure that the distributor is calibrated to be fully advanced at the RPM that you are checking the total at.
Posted By: Mr340
Re: Tooth off on timing chain?........ - 08/17/09 04:31 PM
check your plug wires, I had one with a cut in the insulation and it would short out intermittentlly. it idled fine but under power you could feel the miss., almost like a timing chain studder.
Gary.
Gary.
Posted By: MoparforLife
Re: Tooth off on timing chain?........ - 08/17/09 05:11 PM
Quote:He already stated above that the TDC mark is right on with piston position.
Are you sure the harmonic balancer hasn't slipped on its rubber ring, giving you incorrect timing with the timing light?
Posted By: dynamite
Re: Tooth off on timing chain?........ - 08/17/09 06:45 PM
This may sound crazy but I worked as a tech for dodge dealers thru the 70's and they had a problem with the 360's, when if the motor backfired it could pop the seat off the EGR valve .Dont know if your car still has one on it but it makes that type of noise. EZ to ck...just take off the valve and look at it....the little plunger should be seated in the valve body... Just a thought
Posted By: HealthServices
Re: Tooth off on timing chain?........ - 08/17/09 06:55 PM
Did this happen after the chain set was replaced? I believe there was a run of spockets (sorry don't know which manufacter) that were mis-marked out of the box. It maybe worth it to degree your cam.
Posted By: Anonymous
Re: Tooth off on timing chain?........ - 08/17/09 08:26 PM
Quote:
just checked, the timing chain (new chain) is dead on. Harmonic balancer is good
I could've sworn I posted this. Just exactly how did you check this?
Posted By: prorunner1
Re: Tooth off on timing chain?........ - 08/17/09 09:06 PM
when setting the timing did the timing marks stay steady or were they erratic?maybe the oil pump/distributor drive gear is worn.
Posted By: racincuda
Re: Tooth off on timing chain?........ - 08/18/09 01:57 AM
Not tryin to be a smart a$$ but double check your plug wires.
I kno it sounds too easy but... its happened to me mor than once, 6 & 8 crossed will produce similar symptoms
Let us kno what ya find,
I kno it sounds too easy but... its happened to me mor than once, 6 & 8 crossed will produce similar symptoms
Let us kno what ya find,
Posted By: Posest
Re: Tooth off on timing chain?........ - 08/18/09 02:43 AM
I crossed 5/7 before. Very easy to do, especially plugging back into the cap. Same pop that you are experiencing and lack of power.
Posted By: moparpollack
Re: Tooth off on timing chain?........ - 08/18/09 03:03 AM
I say slop in the distributor. Run a compression check to see if you didn't bend a valve. 
Posted By: CokeBottleKid
Re: Tooth off on timing chain?........ - 08/18/09 11:11 AM
Quote:Quote:
just checked, the timing chain (new chain) is dead on. Harmonic balancer is good
I could've sworn I posted this. Just exactly how did you check this?
Yeees, how did you check this? Need more backround, is there something new or is this the old motor you've been running 13s with for years?
Posted By: dustergirl340
Re: Tooth off on timing chain?........ - 08/18/09 04:09 PM
Different engine, this is a 360. And my 340 runs 12's now. heh
Swapped in new distributor drive gear, the old one was bad. Everything is fine now. Thanks for the input.
Swapped in new distributor drive gear, the old one was bad. Everything is fine now. Thanks for the input.
Posted By: patrick
Re: Tooth off on timing chain?........ - 08/18/09 04:18 PM
I've seen results like this if the distributor drive gear is off a tooth, it gives all kinds of wonky timing values.
Posted By: CokeBottleKid
Re: Tooth off on timing chain?........ - 08/18/09 09:31 PM
distributor drive gear location doesn't matter so long as the distributor vacuum advance has room to allow movement for proper timing setting...
Hers must have been severely worn, or maybe she fixed another problem inadvertently when she replaced it...
Hers must have been severely worn, or maybe she fixed another problem inadvertently when she replaced it...
Posted By: dustergirl340
Re: Tooth off on timing chain?........ - 08/18/09 10:06 PM
it was severely worn
Posted By: patrick
Re: Tooth off on timing chain?........ - 08/19/09 12:25 PM
Quote:
distributor drive gear location doesn't matter so long as the distributor vacuum advance has room to allow movement for proper timing setting...
Hers must have been severely worn, or maybe she fixed another problem inadvertently when she replaced it...
it does and it doesn't, depending on where you put the plug wires. if the DD gear is off (not pointing to #1 at TDC of #1), but you put the plug wires in the same orientation as usually shown, it will show odd advance numbers, because the rotor isn't synced up with the mark on the balancer. if you orient the plug wires so that at TDC of #1, the #1 plug wire is over the dizzy rotor, things will look OK relative to the timing mark on the balancer.
Posted By: Anonymous
Re: Tooth off on timing chain?........ - 08/19/09 03:41 PM
Quote:Quote:
distributor drive gear location doesn't matter so long as the distributor vacuum advance has room to allow movement for proper timing setting...
Hers must have been severely worn, or maybe she fixed another problem inadvertently when she replaced it...
it does and it doesn't, depending on where you put the plug wires. if the DD gear is off (not pointing to #1 at TDC of #1), but you put the plug wires in the same orientation as usually shown, it will show odd advance numbers, because the rotor isn't synced up with the mark on the balancer. if you orient the plug wires so that at TDC of #1, the #1 plug wire is over the dizzy rotor, things will look OK relative to the timing mark on the balancer.
You should be a politician. The "simple" way to say this is, that it "will be out of time" if the wires are in the wrong hole.
The ONLY REASONS that any factory manual specifies a certain way to install a dist. are:
So the assembly line folks can wrench, repeat
So the vac. advance sits OK
So the plug wires "lay" right
So a tuneup mech. sees what he expects to see.
There ARE a few engines that matter. One series are the GM V6's. On some of these engines, the dist. towers are "paired" two towers closer together, then a wide space, so if you get the wires off just one hole, it just won't run right.
When I got my first car, a 57 Chev 265, I didn't know there was a "right" way. I used to just drop the dist in and go.
Posted By: patrick
Re: Tooth off on timing chain?........ - 08/19/09 06:20 PM
I'm not a politician, I'm an engineer.... 