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Timing sprocket marks

Posted By: Dart 340

Timing sprocket marks - 06/04/08 12:52 PM


While I have my engine torn down I am checking the
timing sprocket marks with TDC etc. Here's the weird
thing. The alignment marks are off a little, maybe not quite a gear tooth, or maybe just. I find TDC on fire stroke and check that with valves / cam timing
and it seems correct. Both valves closed and preload
set right. Used a dial indicator to exactly find TDC and same with valves so I know the two are where they should be. Whats up? Can the marks be "off" somewhat on the chain set?
Posted By: 79powerwagon

Re: Timing sprocket marks - 06/04/08 01:43 PM

Yes, it happens all the time, thus the use of offset keys, eccentric bolts, etc. It it really only important if you're building a high-speed/high-power race engine. A stock street engine won't be an issue. You think they get that precise at the factory when they're throwing that stuff together?
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 01:53 PM

yes marks can be off. i recently built a 360. used a Mancini roller set and the marks were 4 teeth off. that put my valves 68 degrees adv. till it broke a valve face off and exploded my motor. each tooth on the crank gear is 17 degrees. i am not saying anything bad about Mancini because everybody gets a bad part sometimes. it's weather the make it right or not that counts. at this point they are working with me. so compare yours to other brands to make sure yours is marked right. i will enclose a pic (if i can downsize it enough) to show correctly marked and not.

Attached picture 4466733-P5230003.JPG
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 01:55 PM

Quote:

Yes, it happens all the time, thus the use of offset keys, eccentric bolts, etc. It it really only important if you're building a high-speed/high-power race engine. A stock street engine won't be an issue. You think they get that precise at the factory when they're throwing that stuff together?



Well that's what I figured, but if the centerline of the lobes lines up with TDC I can't see how it would
matter too much. I know after market parts can vary also. Hell I'm just happy I tore it apart to see what was wrong before real damage happened.
You know, you really should use the right width key in the key slot too..... well water under the
bridge, it's fixed now.

Thanks for the info.
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 02:03 PM

yes i agree. i didn't have another gear set around when i put it together to check. so this is what happenes when you run 4 teeth off.

Attached picture 4466765-P5200001.JPG
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 02:48 PM

Quote:

yes i agree. i didn't have another gear set around when i put it together to check. so this is what happenes when you run 4 teeth off.



Holy crap, that's awful!

My marks are off like one tooth-ish. But I did check
valve position and tdc and it's where it should be
when both valves are closed so I'm going to assume
this is good enough to go. The marks are just kind of weird on this set. they look more like the letter o than a real mark......

Very sorry your engine crashed. Hopefully it's on the mend now.
Posted By: buildanother

Re: Timing sprocket marks - 06/04/08 02:55 PM

Wow, that is a crappy marked crank sprocket, although it is the dot by the keyway that is just indicating which of the 3 keys are the "straight up" position. There looks to be a faint dot mark shown more towards the outer edge of gear around 4 teeth to the left of that key. Never use the mark at keyway to line up with the cam sprocket dot, and another good reason for dialing in cam.
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 03:10 PM

Isn't dialing in pretty much the same as finding TDC and center of the lobe? So would you have to use and offset key if it is off?
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 03:19 PM

i agree there is a speck of a mark in the correct place but i couldn't see it when i put it together. they put the big mark matching the cam gear on the keyway. if i built motors offen i might have thought hey the mark isn't always on the keyway. but who am i to question they way they make gears. heck there is 3 keyways. i know what they are for but i couldn't tell you where they should put the correct mark. all i wanted to do was make it dot to dot.
this cam pistons and rockers were all happy together before. so i didn't worry about degreeing it. i bal. the bottom end and put on a new timming set, BM flex plate,new harm. bal. and thought i was good to go. as you can see there isn't much left of my KB107.
Posted By: mopars4ever

Re: Timing sprocket marks - 06/04/08 03:22 PM

Quote:


Isn't dialing in pretty much the same as finding TDC and center of the lobe? So would you have to use and offset key if it is off?

Maybe in a round about way. I guess you can do it that way if your just looking for O degrees advanced/retarded. But I wouldn`t. Mike
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 03:24 PM

Dart 340 i looked at the valves at TDC too and they were closed. so i guess that isn't a good indcator.
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 03:52 PM

So how did you have a collision then?

I checked mine after the gears and chain were installed. I don't see how it can hit if you verify that piston TDC and valve opening / lobe center are ok? Just trying to learn. I have a degree wheel collecting dust somewhere... never used....

I needed to replace a stripped out eccentric key so
I never changed the alignment of the gears just slid a new (right size) key in. I wanted to check what someone else had done way back when because they did not install the cam retaining bolt correctly.
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 04:07 PM

i don't know i guess it was just advanced enough to hit it as it was closing. it ran petty good i just had some lifter noise. and i was trying to figure that out. got 39 miles on it doing 45 MPH when BANG and everything was quite and i was coasting.

Attached picture 4467066-P5200003.JPG
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 04:15 PM

Quote:

i don't know i guess it was just advanced enough to hit it as it was closing. it ran petty good i just had some lifter noise. and i was trying to figure that out. got 39 miles on it doing 45 MPH when BANG and everything was quite and i was coasting.



Good god, that is not a pretty sight.

Spun mine over by hand a bunch of times. Hope that it's good to go.
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 04:35 PM

nope it is ugly. makes me sick. the car is all done and now it doesn't have a motor. but a redo is in progress.
Dart 340 did u use any clay to check for clearance?
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 04:45 PM

Quote:

nope it is ugly. makes me sick. the car is all done and now it doesn't have a motor. but a redo is in progress.
Dart 340 did u use any clay to check for clearance?



I would puke.....

No I didn't, but I have put a couple hundred miles on the car since I bought it a few at over 5,000 RPM. The guy that built mine used a 5/32 key in the cam way instead of 3/16 and also used a bad conical washer with no loctite so the bolt came loose and I lost fuel pressure. Tore it apart and that's what I found. I just was checking timing and that's what I came up with, marks off, or what appears to be the only marks I can find, were off like half a tooth to a tooth. I put a TDC finder in the no.1 cyl and put the piston at exactly tdc then checked the valves. Preload was good and they appeared to travel correct during rotation so it appears the cam lobe is pretty close to center...

I don't honestly know how to check it any other way.
Posted By: MoparforLife

Re: Timing sprocket marks - 06/04/08 05:21 PM

The problem with the multi-keyway gears is just what is pictured. The marks by the keyway are usually not the ones that are used to line up. There usually an index timing mark. There really won't be a whole bunch of crank and cam position change. a couple of degrees one way or but not a 'few teeth' one way or the other.
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 05:39 PM

that is right. i have had to learn way more about timming sets than i wanted to. it has a -4 and a +4 keyway too but the marks for them. they are almost ivisable too or i would have figured it out . maybe. if you look hard at that pic. you can see a pine needle on the ground it's a good closeup. it's a crazy except for the few with blowers or specal setups. probably 98 % of the people just put them in straght up or dot to dot. Comp Cams web site says they gring them 5 degrees advanced anyway so why advance it more. i know there is a group of builders out there that has a reason. just not us reg. guys. so my finished car sets there waiting for a new heart.

Attached picture 4467273-P5240001.JPG
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 06:12 PM

Quote:

The problem with the multi-keyway gears is just what is pictured. The marks by the keyway are usually not the ones that are used to line up. There usually an index timing mark. There really won't be a whole bunch of crank and cam position change. a couple of degrees one way or but not a 'few teeth' one way or the other.



Well I'm hoping since mine ran well before I took it apart it will be fine once I fire it up tonight. I didn't change anything. Maybe next time I have to tear it down I will go through the instructions from Edelbrock and actually degree it.
Posted By: RobX4406

Re: Timing sprocket marks - 06/04/08 07:34 PM

Hate to say this... 65cuda, your issue was installation error. It sucks tht this happened. I've seen this a bunch of times and was pretty common in the 80's when cloyes true rollers were popular. People would bring in a part and the instruction sheet was neatly folded just like the manufacturer had placed it in the box. Never disturbed or read by the installer.

There are marks on the crank gear for lining up with the cam gear. See the circled areas of the picture. I've seen guys put the gear on for 4* advance and then line up the zero mark on the crank gear, so this isn't a rare occurrance.

IMO, you got a good part and it wasn't mancinis fault your issue occurred. Another real good reason to degree in the cam. Had degreeing been done, you'd have caught the issue before the damage was done.

Again, it sucks this happened to you.

Attached picture 4467481-4466733-P5230003.JPG
Posted By: Anonymous

Re: Timing sprocket marks - 06/04/08 07:43 PM

I've never understood why guys won't take the extra 10 minutes and the effort needed to degree in the cam!

I'm not going to let "Bubba" mis-stamping my set ruin MY engine!

My .528 MP cam and Cloyes true roller was 8* retarded despite being installed in the "straight up" postion. Good thing I checked, huh?
Posted By: Dart 340

Re: Timing sprocket marks - 06/04/08 08:02 PM


Well I guess it's good you checked then. If I were to install a new cam I would degree it or have someone do it for me. I was merely wanting to do
a "spot check" on mine. Ran good prior to the cam bolt coming loose.

Looks like all the major cam players have easy instructions online to do it.
Posted By: 65cuda

Re: Timing sprocket marks - 06/04/08 09:14 PM

i did read the instrutions. they made no sense. it said use the dot for straght up and use the +4 if you want to advance it and so on. but i couldn't see the speck or the +4 as in the pic.
again i would have dailed it in except that had already been done. i just redid the bottom end. it should have the big mark that is most important by the tooth and the speck by the keyway as this cloyes set. notice they even shaped the keyway like the mark so u would know which keyway to use.

Attached picture 4467703-cloyes.jpg
Posted By: Anonymous

Re: Timing sprocket marks - 06/04/08 09:48 PM


Quote:

again i would have dailed it in except that had already been done. i just redid the bottom end. it should have the big mark that is most important by the tooth and the speck by the keyway as this cloyes set.



again, how could it be dialed in if you're changing the timing chain?!

Having "that mark here" and "this mark there" really doesn't mean anything in the broad scheme of things. It's up to you to check out their accuracy. Usually the dot means straight up, triagle means 4* advanced and square means 4 degrees retarded.

I'll be honest, I don't own a cam degree kit but a friend does and we use it on EVERY cam I install anymore. Stock or not, marked or unmarked, sugar coated or whole wheat!

Mancini doesn't owe you a dime.
Posted By: Dart 340

Re: Timing sprocket marks - 06/05/08 03:37 AM


So I put this thing back together after the cam bolt coming loose. Now I need to be quite clear that I only slid the gears back enough to put a new key in and that was it. The gears and chain did not come
off the car, and were not rotated.

So everything is back together and my timing (with a light) advanced like 15 degrees and the damn thing is knocking and detonating. Put some
octane booster in and it did help. Also spun this disty so I am at 15 before and it seems better.

Question is how did the timing change? and second,
now I'm a little nervous about cam timing. I found my degree wheel. Thinking it fits very nice inside the crank pulley. Maybe I can make a mark on the pulley for tdc and how it relates to the wheel, and do a degree in check like that just to be certain the dang thing is close. Not sure whats going on.

Any thoughts?

Thanks,

Doug
Posted By: 65cuda

Re: Timing sprocket marks - 06/05/08 01:11 PM

was the keyway wollered out? but even with that it shouldn't change that much. offset keys would move it more than that could. did u compare your marks to my right and wrong pics. i think at this point i would try the degree wheel. we know what happens if it is too far off.
Posted By: Dart 340

Re: Timing sprocket marks - 06/05/08 01:19 PM

Quote:

was the keyway wollered out? but even with that it shouldn't change that much. offset keys would move it more than that could. did u compare your marks to my right and wrong pics. i think at this point i would try the degree wheel. we know what happens if it is too far off.



I do know he had a .156 wide key in it, and I fit a
.188 key in there. It seems like the wider key was a very good fit. So either it was widened out, or he used the wrong one in the first place, which would explain why the pump eccentric rounded it off etc. So yes, I guess it could be off .030 from what it was.

I think I will try the degree wheel in the crank pulley as it fits perfect. Maybe hold it with some magnets etc and see where the cam CL come in at. At least I can discard it as a problem or verify I have to tear something back down.
Posted By: 79powerwagon

Re: Timing sprocket marks - 06/05/08 01:33 PM

Hey Doug, where in WI are you? I'm around Menomonee Falls. Maybe I can lend a hand?

Eric
Posted By: Dart 340

Re: Timing sprocket marks - 06/05/08 01:40 PM

Quote:

Hey Doug, where in WI are you? I'm around Menomonee Falls. Maybe I can lend a hand?

Eric



Eric,

I'm up by Hudson (Near twin cities) I think you are
by Milwaukee is that correct?
Posted By: 65cuda

Re: Timing sprocket marks - 06/05/08 01:40 PM

i think thats a good ideal. to me it doesn't explane how your timing got off so much. but on the other hand they are related. one tooth on the crank gear being 17 degrees. when they cut those +-4 keyways they are just a fraction of a tooth different. i am not smart enough to work backwards to figure out the .000 to degrees and see if .030 would put you off that much.
Posted By: 79powerwagon

Re: Timing sprocket marks - 06/05/08 01:46 PM

Yup Doug. Too far to lend a casual hand! Oh well, there are other members nearer to you, maybe they can chime in and give assistance! Sometimes it only takes a second set of eyes to see the obvious that you may have over-looked. I had a friend gawking at my 440 when I first installed it, and he noticed I had the plug wires on wrong, even after going through them 3 times myself!

Hey, it happens!
Posted By: Dart 340

Re: Timing sprocket marks - 06/05/08 01:52 PM

Thanks for the offer. My dad is visiting this weekend I'll have him take a look too. He worked for
chrysler for 32 years. At 70 he's forgotten more than I know about mopars!

I'll let you know what I find.

thanks!
Posted By: Dart 340

Re: Timing sprocket marks - 06/05/08 01:54 PM

Quote:

i think thats a good ideal. to me it doesn't explane how your timing got off so much. but on the other hand they are related. one tooth on the crank gear being 17 degrees. when they cut those +-4 keyways they are just a fraction of a tooth different. i am not smart enough to work backwards to figure out the .000 to degrees and see if .030 would put you off that much.



I'm thinking if I have to tear this down again, I might change this big monster loper to something more streetable too.
Posted By: Dart 340

Re: Timing sprocket marks - 06/05/08 01:55 PM

Quote:

Yup Doug. Too far to lend a casual hand! Oh well, there are other members nearer to you, maybe they can chime in and give assistance! Sometimes it only takes a second set of eyes to see the obvious that you may have over-looked. I had a friend gawking at my 440 when I first installed it, and he noticed I had the plug wires on wrong, even after going through them 3 times myself!

Hey, it happens!



Eric, you may have seen this car in the past. The guy I bought it from lived in Union Grove and used to run it at the strip there... little more street friendly now though.
Posted By: 65cuda

Re: Timing sprocket marks - 06/05/08 02:00 PM


yes an exta set of mopar eyes could be invaulable
Posted By: Dart 340

Re: Timing sprocket marks - 06/06/08 06:55 PM

So I have this thing all together and now I have a
pretty scary knock only when the engine is cold. Sounds like a hard hammering best I can tell on the top end, but after a few minutes of idling it goes away and doesn't come back until the engine is cold again. I have rev'd it up over 4000 no problems once it's warm. Could it be a bad lifter or 2 or maybe I need to set preload again?

Any thoughts on what can cause this? can a bearing make that bad of a noise?
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