I thought my timing chain had jumped and I embarked on replacing it...now, I don't know.

It looks like the timing chain did NOT jump a sprocket as the timing marks line up after I got the cover off (8 hours to get that far at my pace...slow.)

I have two questions for those of you familiar with this type of repair:

#1) I checked the distributor at TDC on the number one cylinder and found it was off. The rotor was pointed between the #5 and the #1. The manuals and the emissions sticker say to time the motor at 10 BTDC. Should I have checked the rotor alignment at 10 BTDC instead of TDC? Is this why I found the timing marks lined up, because I tested it wrong?

#2) I found I have a double roller timing chain already installed. It has almost ½ inch deflection. The manuals say the stock timing chain can have up to ½ inch deflection. Is it the same for a double roller timing chain? Or is this excessive chain deflection my problem? In other words, should I replace the timing chain? It must have at least 50K miles on it, maybe up to 85K (I don’t know when it was put in.

#3) If it's not the timing chain, and I have fuel, and I have spark then what could it be? Compression?

Thanks for your help!

Lee at the foot of Pikes Peak

 

after spending that much time on it, put in a new chain, maybe gears if they don't look so good.

When you get it back together try turning the distributer slowly clockwise then counterclockwise while someone else turns the motr over. Are you sure that you are getting enough fuel? Is your firing order wrong?
Did you do anything to it beofre it stopped starting? Has it sat for a long time or anything?
Is the spark a healthy blue/white, or is it a pale yellow? ignition components are pretty cheap, you might need a new coil, or condenser, look forward to hearing more.

 

you might also just take the distributor out and re align it to where it should be while you have everything else lined up. maybe the last person that installed the timing chain had messed with the distributor and didnt install it properly? just a thought

good luck
later

 

The deflection should be the same regardless of the type of chain used; the length of the chain is the same. If you've got it at TDC, the rotor should be slightly between 1 and 5, but not really that close to 5 in my opinion.

Like millertime said, since you're in there, might as well replace the chain and gears with a fresh set.

 

Hi, just finishing a gm piece of garbage that strecthed and flipped it's timing chain a couple of teeth.
Bascially, when you are at TDC, your #1 piston is at TDC. You should feel this 2 ways. First is use a long paperclip that has been straightened out. Put that in the #1 sparkplug hole. Then put your finger in the hole. When the air blows out, AND the paperclip moves up and stops, and is not moving up OR down. That is TDC.
Move the crank back and forth to that point. and feel for slop in the chain. The actual test is to move it so you have max defelection of the chain. If you have 1/2" replace it and the gears. Actually, I've come to the conclusion that any slop in the chain throws off the computer controls.
At TDC you put the distributor in so that it is at #1, not off by any degree. Cut a hole in your old dist. cap so you can see it at #1. This is easy on Fords!!!! gm garbage is in the back and extremely difficult to do.
You have set TDC, and timing. Now all you have to do is put everything back together. Disconnect the slop, finish timing with the timing light. reconnect and you are done.
Bruce (Big Red Bronco)

 

I finally got a new timing set in - along with new water pump, thermostat, serpentine belt, etc.- and I can get it to fire up by turning the distributor while cranking but, it's missing like crazy and not running right.

With a timing light I see that it will only run and idle when the timing is at 30 BTDC - actually, off the scale so 32 or 33 BTDC. If I try to back it down to 10 BTDC, like the VECI label calls for, the truck dies.

The Bronco already had a double roller timing chain installed and I recalled that the original owner told me he had an aftermarket camshaft installed. I found a receipt from 4/93 but it does not list a brand. It has a part number but no brand name. Also, I installed the “after 9/87” timing chain because it is a double roller style. The “before 9/87”, which the truck is, is not a double roller.

Does the timing chain have to match the camshaft? Same brand?

The timing light misses when I am timing. About every fourth or fifth time it fires it misses. The light does not flash. Does this indicate the number 1 cylinder is missing?

Is it possible the source of the miss is also the culprit in the timing fiasco? More likely the reverse I think.

Thanks for any insight you can provide.

Lee in Colorado

 

What was the root problem in the first place? In other words, what led you to believe it had jumped time when in fact it had not? Whatever that was may still be your problem.

It sounds like your aftermarket cam was degreed in when it was installed. If that's the case, then when you are at TDC the timing marks will not line up. The only thing I can think of to correct this now is to un-degree it. At TDC with your timing marks aligned, pull the distributor and re-install it exactly on #1.

 

When you are at tdc on #1 is the balancer mark close to zero on the scale?Is the keyway on the crank striaght up at tdc? If the rubber inner piece on the balancer slips then the timing marks are usless.The fact that you have to crank it to 30 deg to get it to run makes me think the timing marks maybe off.

CB

 

I was led to believe the timing chain slipped because at TDC the rotor was pointed midway between the # 1 post and the #5 post on the distributor. The general consensus was that this was a problem.

When I opened it up, after connecting many synapses in the gray matter and many hours, I discovered the timing marks were indeed lined up. However, I installed a new timing set (sprockets and double roller chain) because the old one had over ½” of play and would need to be replaced soon anyway.

At TDC the timing marks do line up. It all looked good in that regard. The tension is vastly improved on the new chain set. I simply rotated the distributor so that the rotor lined up with the #1 post at TDC and then tried to fire it up. I had to rotate the distributor a little to get it to fire. Now it will only idle at +30 BTDC. But, it won’t fire up here. I have to rotate the distributor to about 35 BTDC (if it actually had that indicator on the damper) and then turn it back to 30ish BTDC to get it to idle.

Weird huh? I don’t recall a rubber ring on the damper just a key-slot that lines up with the timing mark.

I will try reinstalling the distributor with the rotor pointed at #1 post. Seems like it is off one gear. I’ll let you know how it goes.

Thanks for your help!

Lee in Colorado

 

It does'nt matter what tooth the dist. gear is on as long as you can time it.If you actually have 35 have deg initial timing the motor would be very hard to start if it would start at all.The dampner has an inner rubber piece.When you were at TDC and you installed the dampner where was the timing pointer at.It should be close to zero on the scale.Put it back to TDC on #1 and check the timing marks.If the "inner" rubber piece slips the timing scale is useless.


CB

 

Just to make sure you're not fighting something you don't need to, what does the timing pointer look like on your engine. Some of the pointers have more than one thing on them that can be confused for the actual indicator point. This is in no way intended to sound like I don't think you know what you are doing. But I have seen posts here before with people asking which point is actually used to set the timing.

 

At TDC the damper does line up at zero on the timing mark. The timing mark is pretty clear-it has a straight edge the says "time" on it so I don't think I am using the wrong mark.

There seems to be a pretty serious vacuum problem. Here is another post I put up:

Vacuum pressure regulator? '87 302 EFI
After replacing a timing chain and a few other parts (see "timing chain" post in this forum) I could not get the 302 EFI on my '87 Bronco to start without turning the distributor. Then, after I got it running, it missed - a lot - and runs real rough.

While trying to diagnose the problem I removed a vacuum hose on the throttle body and the truck runs great. No missing. The idle seems a little high but, it isn't missing. [ timing is still set at 35 BTDC but it starts and runs well - except for the unplugged vacuum line hiss]

Is there a pressure regulator for the vacuum system? Or do you know which component is the problem? EGR? (I cleaned it up - removed a lot of carbon) Or are these the symptoms of a leak?

The vacuum hose I removed goes to some device, on the drivers side fender wall, that has a mechanical line that goes to the throttle. [Update: the device is the "servo assembly" that is the "throttle actuator" whatever that is] It seems like it a component of the cruise control. That device has a vacuum line that goes through the firewall so I think it goes to the AC system.

Any help would be appreciated.

Lee in Colorado Springs

 

It sounds like your distributor is installed in the wrong position. Rotate engine w/ ratchet and socket until timing mark aligns w/ 10 BTDC mark. The distributor rotor should be pointed very near #1 post on distributor. If not, the distributor is mispositioned. Remove distributor rotate shaft and reinstall. If you lift distributor slowly, you can feel the gears release, rotate rotor, and reengage at next position.

I had to reposition distributor a couple of times after I put head gaskets on my 90 Bronco.

I assume you are setting dynamic timing w/ the SPOUT jumper removed from the lead from the distributor? You cannot set timing w/ SPOUT engaged.

good luck