Slightly worried after timing up the Nova.
TDC is marked with a load of punch marks, very clear.
The next timing mark is an "I". The next timing mark after that is an "I"
I have timed the ignition to the first "I" which I thought was the static idle, but when I dial back the strobe to TDC the first mark is at 18 degrees BTDC, not 8 degrees. I have heard about an intermediate (2000 rpm) timing mark at 22 degrees BTDC. Is this it?
There does not appear to be a mark between TDC and the first "I".
Should I dial the strobe to 8 degrees and adjust for TDC, or leave it as it is?
Has anyone else come across these odd markings?
Thanks guys,
Lauren
Flywheel Timing Marks
Re: Flywheel Timing Marks
Hi Lauren in the Haynes Man it states T - TDC on no1. 1 - static advance at idle. 11 - advance at 2000. 111 - advance at 4500. Hope that helps.
Re: Flywheel Timing Marks
Have you got the vac advance disconnected and blanked off, for the static idle?
Also there usually are some factory balance weights on the flywheel......someone may have confused these with timing marks
Also there usually are some factory balance weights on the flywheel......someone may have confused these with timing marks
Re: Flywheel Timing Marks
Thanks for your responses guys, it's much appreciated!
OK, I've had a really good look at my flywheel today and in the direction of normal rotation I have found the following:
A circular raised casting nib, followed by...
A single scribe mark which has been highlighted with 3 punch marks and which I have assumed is TDC for cam timing etc., followed by...
A single scribe mark, followed by...
Another single scribe mark. There are no more factory markings that I can find.
After the fun I had with the distributor seal I lost the timing so had to dust off the strobe light. The engine runs great if I set the idle timing to the first mark before my assumed TDC (vacuum line plugged as Dave says). I set this with the strobe dialled at zero degrees and then adjusted the distributor until the first mark lined up with the pointer on the engine.
What was concerning me yesterday was that when I rotate the degree dial on the strobe until the assumed TDC mark comes into line with the pointer, I think I am right in saying that the strobe dial should then be reading the number of degrees between TDC and the first mark, and instead of getting the factory 8 degrees I am seeing something like 18 degrees.
Anyway, the engine seems to be most comfortable at the first mark (I tried setting it to 8 degrees before the assumed TDC mark and the engine sounded very uncomfortable and wouldn't idle, let alone rev), and this was clearly the mark that I had timed it to before, so several thousand miles with no pinking at high speed or under heavy acceleration.
My confusion is down to the single scribe marks for each advance point - as Tony says, I was expecting one, two and three scribe marks,which would have been unequivocal. Nevertheless, I have searched thoroughly for a scribe mark before the assumed TDC mark (which as Dave says could have been incorrectly identified as TDC) and there is nothing, other than the casting pip, which I believe is not to be taken as TDC.
Do the experts concur? Has anybody else got this confusing set of flywheel markings???
Lauren
OK, I've had a really good look at my flywheel today and in the direction of normal rotation I have found the following:
A circular raised casting nib, followed by...
A single scribe mark which has been highlighted with 3 punch marks and which I have assumed is TDC for cam timing etc., followed by...
A single scribe mark, followed by...
Another single scribe mark. There are no more factory markings that I can find.
After the fun I had with the distributor seal I lost the timing so had to dust off the strobe light. The engine runs great if I set the idle timing to the first mark before my assumed TDC (vacuum line plugged as Dave says). I set this with the strobe dialled at zero degrees and then adjusted the distributor until the first mark lined up with the pointer on the engine.
What was concerning me yesterday was that when I rotate the degree dial on the strobe until the assumed TDC mark comes into line with the pointer, I think I am right in saying that the strobe dial should then be reading the number of degrees between TDC and the first mark, and instead of getting the factory 8 degrees I am seeing something like 18 degrees.
Anyway, the engine seems to be most comfortable at the first mark (I tried setting it to 8 degrees before the assumed TDC mark and the engine sounded very uncomfortable and wouldn't idle, let alone rev), and this was clearly the mark that I had timed it to before, so several thousand miles with no pinking at high speed or under heavy acceleration.
My confusion is down to the single scribe marks for each advance point - as Tony says, I was expecting one, two and three scribe marks,which would have been unequivocal. Nevertheless, I have searched thoroughly for a scribe mark before the assumed TDC mark (which as Dave says could have been incorrectly identified as TDC) and there is nothing, other than the casting pip, which I believe is not to be taken as TDC.
Do the experts concur? Has anybody else got this confusing set of flywheel markings???
Lauren
Re: Flywheel Timing Marks
Are you sure you put your dissy back in the right position?
P34 in my red Haynes shows a dwg showing the correct position.
My front crank pulley had a notch at the top when at tdc........but I'm not sure if it was a factory mark, or a diy add on.
If the flywheel marks have been messed with, take one or both cam covers off, syphon some oil out, there are marks at the rear of the camshaft for tdc.
See Haynes photo 41.10.
When at tdc on the firing stroke, the rotor arm should point to no1 plug lead,and also at the notch on the dissy body
P34 in my red Haynes shows a dwg showing the correct position.
My front crank pulley had a notch at the top when at tdc........but I'm not sure if it was a factory mark, or a diy add on.
If the flywheel marks have been messed with, take one or both cam covers off, syphon some oil out, there are marks at the rear of the camshaft for tdc.
See Haynes photo 41.10.
When at tdc on the firing stroke, the rotor arm should point to no1 plug lead,and also at the notch on the dissy body
Re: Flywheel Timing Marks
Correction:-
you could only have the dissy in the wrong position, if you had the oil pump fitted incorrectly.
you could only have the dissy in the wrong position, if you had the oil pump fitted incorrectly.
Re: Flywheel Timing Marks
Thanks Dave - as far as I know the oil pump has never been out of the engine, and at TDC on the firing stroke the rotor arm does line up with the mark on the distributor housing and #1 plug lead. As you say, if the flywheel markings are in doubt there is always the cam timing marks. I recently changed the cam belts so I know that these both line up correctly with the flywheel at the assumed TDC position. As the cams rotate at half the speed of the crank/flywheel the cam timing cannot be 1 tooth off as this would translate into a much larger angular displacement on the flywheel.
So I think the punch marks have it. Maybe the timing discrepancy I saw was down to me double accounting, adding 8 degrees instead of subtracting, something like that... Anyway, the engine seems to be back on form, revs OK and pulls well with no apparent pinking.
Lauren
So I think the punch marks have it. Maybe the timing discrepancy I saw was down to me double accounting, adding 8 degrees instead of subtracting, something like that... Anyway, the engine seems to be back on form, revs OK and pulls well with no apparent pinking.
Lauren
Re: Flywheel Timing Marks
I was under the car the other day and took the wee plate that covers the flywheel off. Mine has a large raised O on the flywheel, then marks are T, I and II. I checked that the T aligned with cylinder 1 at the top of the stroke and it did. Didn't check at the distributor though but my dissy is on about 90 degrees out so TDC on cylinder 1 the rotor arm actually points to cylinder 2. Doesn't matter as long as the firing order is correct I suppose
Si puo diventare Alfista
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Si puo anche nascere come Alfista
Ma si muore sempre come Alfista
Re: Flywheel Timing Marks
Thanks Stesco, your observations seem to back up my own - the raised "O" then three timing marks, the first being TDC, then the static idle mark and then the full advance mark. Like you I also have my distributor rotated 90 degrees so that the vacuum advance canister misses the chassis bridge over the top of the engine. As you say, as long as the plug leads are moved around be 90 degrees as well, it makes no difference to the firing order.
Lauren
Lauren