Timing mark out 180 degrees
Race Director
Joined: Jul 2001
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Wow- this is just frightening. I guess some have never had an engine apart and/or never thought about and understood the relationship of the cam shaft vs. crankshaft vs. distributor rotor positions.
Somebody please take the timing chain cover off an engine and have a look. Turn the crank so that the dots are lined up, crank dot at tdc and cam dot at bdc. Now turn the crank 360*. The crank dot is at tdc, the cam dot is at tdc. One position represents the top of the combustion stroke, the other the top of the exhaust stroke.
We all know that the distributor rotor needs to point at the appropriate rotor cap wire at the top of the compression stroke and not the exhaust- but that's purely to do with the relationship between the cam and the distributor rotor- nothing to do with crank and cam relative position.
It is impossible to have 'the cam and crank position off by 180*'
Somebody please take the timing chain cover off an engine and have a look. Turn the crank so that the dots are lined up, crank dot at tdc and cam dot at bdc. Now turn the crank 360*. The crank dot is at tdc, the cam dot is at tdc. One position represents the top of the combustion stroke, the other the top of the exhaust stroke.
We all know that the distributor rotor needs to point at the appropriate rotor cap wire at the top of the compression stroke and not the exhaust- but that's purely to do with the relationship between the cam and the distributor rotor- nothing to do with crank and cam relative position.
It is impossible to have 'the cam and crank position off by 180*'
Pro
Joined: Feb 2008
Posts: 556
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From: C3 Forum, Colorado
You can run an engine with the cam 180* out of rotation if you also run your distributor 180* out of rotation. The engine doesn't care. TDC of the #1 cylinder is TDC of the #1 cylinder.
To the original poster, just for the sake of argument, hook your timing light to the #6 spark plug wire and I bet you'll see your timing mark.
You can time your engine this way.
To the original poster, just for the sake of argument, hook your timing light to the #6 spark plug wire and I bet you'll see your timing mark.
You can time your engine this way.
Race Director
Joined: Apr 2011
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From: North of Toronto - Ontario
You can run an engine with the cam 180* out of rotation if you also run your distributor 180* out of rotation. The engine doesn't care. TDC of the #1 cylinder is TDC of the #1 cylinder.
To the original poster, just for the sake of argument, hook your timing light to the #6 spark plug wire and I bet you'll see your timing mark.
You can time your engine this way.
To the original poster, just for the sake of argument, hook your timing light to the #6 spark plug wire and I bet you'll see your timing mark.
You can time your engine this way.
Only the OP knows for sure but when he said he could see the mark on the pass-side with the light, it can't actually be out 180. That would put it down on the underside somewhere (opposite the timing tab).
Not sure on a SBC if you have room there to see it if it was actually out 180, on the BBC you'd have to be under the car I think
I took it as sort of a general statement that it was way off.
Mooser
Le Mans Master
Joined: Mar 2008
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From: Oxford MA-----You just lost the game!!!!
Only the OP knows for sure but when he said he could see the mark on the pass-side with the light, it can't actually be out 180. That would put it down on the underside somewhere (opposite the timing tab).
Not sure on a SBC if you have room there to see it if it was actually out 180, on the BBC you'd have to be under the car I think
I took it as sort of a general statement that it was way off.
Mooser
Keep the shiny side up!
Scott
Thread Starter
Racer
Joined: Jun 2012
Posts: 283
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From: Berlin Township oh
To some posters, thank you for your insightful comments, to others, make sure to stop by the pill cart when it comes around.
I fired her up this afternoon and got out my timing light. Idle is at 600 or so with the vacuum can disconnected. i moved the pickup around to each spark plug and sure enough, # 6 wire is where i get my timing mark to line up. I have about 10 dgrees timing right now. i poped the cap off and if i line up the timing mark to TDC, the rotor points to number 6 wire. very interesting! The strange thing is that the motor runs great, easy starts both cold and warm, no detonation and my plugs are a nice tan color. If the cam is out 180, i think i will just leave it untill winter, it has only been this way for the last 4 years i have had the car, Maybe if i get rambuctious, i will pop off the main drive pully and check the dampner,
I dont claim to be an expert by any means, but i didnt think the engine would run that well with the cam out 180 degrees
I fired her up this afternoon and got out my timing light. Idle is at 600 or so with the vacuum can disconnected. i moved the pickup around to each spark plug and sure enough, # 6 wire is where i get my timing mark to line up. I have about 10 dgrees timing right now. i poped the cap off and if i line up the timing mark to TDC, the rotor points to number 6 wire. very interesting! The strange thing is that the motor runs great, easy starts both cold and warm, no detonation and my plugs are a nice tan color. If the cam is out 180, i think i will just leave it untill winter, it has only been this way for the last 4 years i have had the car, Maybe if i get rambuctious, i will pop off the main drive pully and check the dampner,
I dont claim to be an expert by any means, but i didnt think the engine would run that well with the cam out 180 degrees
Le Mans Master
Joined: Jan 2006
Posts: 6,505
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From: Butler Pa
Think about this people, if the timing mark is correct, and 180* off, then #1 piston is at bottom dead center. The camshaft has nothing to do with any of this. The only explanation is the balancer has spun.
Race Director
Joined: Jul 2001
Posts: 15,892
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Pro
Joined: Feb 2008
Posts: 556
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From: C3 Forum, Colorado
In other words, when the #1 cylinder is at TDC with the timing marks lined up the cam is in the exhaust/intake position instead of the compression/power position.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
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From: Seattle WA
St. Jude Donor '14
Let's back up for a minute without the hostility.
#1 and #6 in a GEN I SBC are companion cylinders; they're at TDC at the same time, but on different strokes - i.e. when #1 is on TDC compression, #6 is on TDC exhaust.
During timing gear installation, aligning the dots with the key at 2:00 and the cam pin at 3:00 means the engine is at TDC compression #6. This is what results in a no-start on many first start-ups, commonly called being "180 out" on timing when the distributor is dropped set for TDC compression #1.
I suspect what happened is simply that the cam is installed correctly, but the builder installed the distributor so that in essence #6 becomes #1 - which works fine...but for sure the timing marks won't line up. Realistically, the engine could be timed to any cylinder...but the timing marks are set for #1.
I don't think any of this requires a ton of hostility - it's interesting to think about and I believe the OP has found that was indeed the case. I expect he can simply find TDC compression #1, reinstall the distributor and be fine.
#1 and #6 in a GEN I SBC are companion cylinders; they're at TDC at the same time, but on different strokes - i.e. when #1 is on TDC compression, #6 is on TDC exhaust.
During timing gear installation, aligning the dots with the key at 2:00 and the cam pin at 3:00 means the engine is at TDC compression #6. This is what results in a no-start on many first start-ups, commonly called being "180 out" on timing when the distributor is dropped set for TDC compression #1.
I suspect what happened is simply that the cam is installed correctly, but the builder installed the distributor so that in essence #6 becomes #1 - which works fine...but for sure the timing marks won't line up. Realistically, the engine could be timed to any cylinder...but the timing marks are set for #1.
I don't think any of this requires a ton of hostility - it's interesting to think about and I believe the OP has found that was indeed the case. I expect he can simply find TDC compression #1, reinstall the distributor and be fine.
Last edited by billla; Jun 22, 2012 at 04:20 PM.
Team Owner
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
I fired her up this afternoon and got out my timing light. Idle is at 600 or so with the vacuum can disconnected. i moved the pickup around to each spark plug and sure enough, # 6 wire is where i get my timing mark to line up. I have about 10 dgrees timing right now. i poped the cap off and if i line up the timing mark to TDC, the rotor points to number 6 wire.
I ask the nurse with the pill cart to give me a couple extra
But I would get back to basics. I would take off the driver side valve cover. I don't know if your crank snouts have a 5/8th bolt or not (inside the damper) bump the motor over until you see the intake valve on number 1 cylinder closing. socket and breaker bar rotate the crank clock wise to bring the #1 piston to TDC. Look at the pointer it should be at the "0" TDC mark if not like many degrees out I would check the damper for breaking the rings apart and it must be replaced. You can do it on the car with a damper installer/ puller. There is a special tool for popping out the timing cover seal.
If the timing indicator and damper mark line up your problem could be as easy as moving your wires around so the rotor is just 10 degrees pat #1 or maybe you have to restab the distrib to to get some cap direction for plug wire routing
Team Owner
Joined: Jan 2006
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From: Crossville TN
It is patently obvious that the cam is installed 180 degrees off from intended indexing and the distributor had to be indexed 180 off to compensate and allow the engine to run. There is no other way that the engine could run fine, but the cam be one-full-crank revolution off.
Is it possible that the damper could have slipped exactly 180 degrees out of position...and then continue to stay right there? Yes. Is it likely? About as likely as me winning the Powerball tonight.
Is it possible that the damper could have slipped exactly 180 degrees out of position...and then continue to stay right there? Yes. Is it likely? About as likely as me winning the Powerball tonight.
Last edited by H P Bushrod; Jun 22, 2012 at 05:51 PM.
Le Mans Master
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From: Butler Pa
Le Mans Master
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From: Oxford MA-----You just lost the game!!!!
OK, here's what I think is going on here: The cam was installed 180* off. So, what the engine builder did, to avoid dis-assembling the engine, is install the distributor 180* opposite, to compensate, and changed the firing order to 65721843, so, naturally, the timing mark is 180* off, but the engine still runs just fine.
OK, by now you've probably figured out that the above is just a bunch of nonsense, but I probably had ya goin' for a second, there! Seriously, If you check the dampener, and it's not spun, I would just leave it alone, and time it from the number 6 cylinder. If it's running just fine, there is really no reason to crack it open. If one of your kidneys was turned sideways, but it worked just fine, would you let a surgeon cut you open, just to turn it back?
Keep the shiny side up!
Scott
OK, by now you've probably figured out that the above is just a bunch of nonsense, but I probably had ya goin' for a second, there! Seriously, If you check the dampener, and it's not spun, I would just leave it alone, and time it from the number 6 cylinder. If it's running just fine, there is really no reason to crack it open. If one of your kidneys was turned sideways, but it worked just fine, would you let a surgeon cut you open, just to turn it back?
Keep the shiny side up!
Scott
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From: Maryville Tn
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The hostility better cease or I see extended vacations from the forum in some of your futures. It's unnecessary.
Thread Starter
Racer
Joined: Jun 2012
Posts: 283
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From: Berlin Township oh
So am i understanding correctly that i can pull my dizzy and rotate it 180 degrees to get my timing mark on the number one wire? i did dif further into the dizzy, removed to rotor and the advance weights are rusty and the little plastic bushings are in peices. i have the Advance kit to install, it apears to me the 2 plates that the springs go onto are rusted to gether. should i be able to move one of the plates? either the top or bottom plate?
Le Mans Master
Joined: Jun 2004
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From: Seattle WA
St. Jude Donor '14
My take is yes. Take the #1 spark plug out and disconnect the coil, then "bump" the engine with your finger over the spark plug hole until you feel #1 coming up on compression. Set the engine to about 8-12 BTDC and install the distributor so that the rotor points to the #1 tower. If the distributor won't drop because of the oil pump tang, bump the engine until it drops and then re-check positioning...you may have to "walk" it ahead or back a tooth. This will get you in the ballpark, and should only take about 30 minutes, max. BEFORE doing this, I would take the precaution of finding TDC compression #6 as well, and marking the balancer. This way, if we have to reset you've got a reference mark. Also, double-check that the wires are on the right towers.
Look at it this way - worst case it won't start or run correctly when you do this. So you swap it back to #6 and we look at other causes. You're out maybe an hour max.
A photo is worth 1,000 words, but yes - the plate the weights are on should be able to move freely to the limit of the pin that sticks down from the plate directly attached to the distributor shaft.
Last edited by billla; Jun 22, 2012 at 07:06 PM.
Le Mans Master
Joined: Jan 2006
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From: Butler Pa
How can rotating the distributor change the position of the crankshaft by 180* when #1 cylinder fires?
Le Mans Master
Joined: Jun 2004
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From: Seattle WA
St. Jude Donor '14
I think everyone would agree that an hour's investment in troubleshooting to see if the issue can be resolved simply is better than just diving in and pulling the balancer and the front cover, fair? If what I suggested doesn't work then the more invasive troubleshooting can go from there. Worst case, wasted hour