Distributor and TDC
Discussion
I am checking the timing and using a piston stop have found that TDC seems to be about 2 degrees before the TDC mark on the crank pulley.
Granted my paint tip pen tip was a bit fat but on a serp, as it is that so it indeed also be on the actual mark on the pulley so I just trust the mark on the pulley instead?
At TDC, rotor arm sits around halfway between two terminals on the dizzy. I checked the that it was on the compression cycle and it was, pointing to around7 o'clock while looking at it from the front of the car.
Which of the two is piston 1, the one before TDC or after? If I move the pulley to around to say 10 deg BTDC, should the rotor line up with a terminal?
The rotor arm can be moved with a finger clockwise by about 5mm measured at the copper end.
Sucking on the vacuum hose, I can hear a faint click in the dizzy but see nothing moving.
Do these both sound right?
(posted on FB too but no response)
Granted my paint tip pen tip was a bit fat but on a serp, as it is that so it indeed also be on the actual mark on the pulley so I just trust the mark on the pulley instead?
At TDC, rotor arm sits around halfway between two terminals on the dizzy. I checked the that it was on the compression cycle and it was, pointing to around7 o'clock while looking at it from the front of the car.
Which of the two is piston 1, the one before TDC or after? If I move the pulley to around to say 10 deg BTDC, should the rotor line up with a terminal?
The rotor arm can be moved with a finger clockwise by about 5mm measured at the copper end.
Sucking on the vacuum hose, I can hear a faint click in the dizzy but see nothing moving.
Do these both sound right?
(posted on FB too but no response)
If you have used a dead stop to establish TDC then believe it.
The harmonic damper (the piece with the markings on) is rubber bonded to the crank pulley so a slight misalign is quite normal. For the benefit of others if the alignment is further off from TDC then the bond of the rubber has failed and the whole pulley must be replaced. However, the pulley is part of the balance of the engine so the new one must be drilled for balance in the same way and position as the old one.
The dizzy rotor arm should point roughly at number one contact when the crank is about 12degrees before TDC. Where it points in terms of a clock dial is not relevant as long as it is pointing at lead number one. If it is not then it can be lifted out and turned one drive tooth a slotted back in again.
Steve
The harmonic damper (the piece with the markings on) is rubber bonded to the crank pulley so a slight misalign is quite normal. For the benefit of others if the alignment is further off from TDC then the bond of the rubber has failed and the whole pulley must be replaced. However, the pulley is part of the balance of the engine so the new one must be drilled for balance in the same way and position as the old one.
The dizzy rotor arm should point roughly at number one contact when the crank is about 12degrees before TDC. Where it points in terms of a clock dial is not relevant as long as it is pointing at lead number one. If it is not then it can be lifted out and turned one drive tooth a slotted back in again.
Steve
I read that on a serp the TDC mark is likely to be spot on but I just wanted to be sure.
That's good info re the 12 deg, I'll move the crank pulley round and see. Will the rotor line up exactly or should I expect it to be slightly out?
Before running the engine with a strobe, while it is in bits, is there anything I can do to test that the mechanical and vacuum advance on the dizzy is working properly?
That's good info re the 12 deg, I'll move the crank pulley round and see. Will the rotor line up exactly or should I expect it to be slightly out?
Before running the engine with a strobe, while it is in bits, is there anything I can do to test that the mechanical and vacuum advance on the dizzy is working properly?
You can just look for a bit of play if you rotate the trigger wheel back and forth with your fingers. The only likely fault with the advance / retard is the shaft corrodes so it all locks up solid, but if there is a bit of backlash chances things are OK. As for the vacuum- you should be able to see the trigger head move around the edge of the distributor body as you suck on the pipe. If it does not move, remove the vacuum unit and make sure the trigger head with slide around in its slots.
blitzracing said:
You can just look for a bit of play if you rotate the trigger wheel back and forth with your fingers. The only likely fault with the advance / retard is the shaft corrodes so it all locks up solid, but if there is a bit of backlash chances things are OK. As for the vacuum- you should be able to see the trigger head move around the edge of the distributor body as you suck on the pipe. If it does not move, remove the vacuum unit and make sure the trigger head with slide around in its slots.
So that 5mm of clockwise sprung amount of movement on the rotor is correct, Mark? I'll take off the black plastic cap from the distributor body, to see the mechanism and if it moves, but there is definitely an audible click when I suck on the pipe.
Steve_D said:
If you have used a dead stop to establish TDC then believe it.
The harmonic damper (the piece with the markings on) is rubber bonded to the crank pulley so a slight misalign is quite normal. For the benefit of others if the alignment is further off from TDC then the bond of the rubber has failed and the whole pulley must be replaced. However, the pulley is part of the balance of the engine so the new one must be drilled for balance in the same way and position as the old one.
The dizzy rotor arm should point roughly at number one contact when the crank is about 12degrees before TDC. Where it points in terms of a clock dial is not relevant as long as it is pointing at lead number one. If it is not then it can be lifted out and turned one drive tooth a slotted back in again.
Steve
Wound the engine back to 12 deg BTDC and it is still between '7 o'clock and 8 o'clock' ie it is not pointing at anything directly. The harmonic damper (the piece with the markings on) is rubber bonded to the crank pulley so a slight misalign is quite normal. For the benefit of others if the alignment is further off from TDC then the bond of the rubber has failed and the whole pulley must be replaced. However, the pulley is part of the balance of the engine so the new one must be drilled for balance in the same way and position as the old one.
The dizzy rotor arm should point roughly at number one contact when the crank is about 12degrees before TDC. Where it points in terms of a clock dial is not relevant as long as it is pointing at lead number one. If it is not then it can be lifted out and turned one drive tooth a slotted back in again.
Steve
Presumably, this means that the dizzy needs rotating but to choose one of them for cylinder 1, so the car starts so I can set the timing, would that be the one behind or ahead of the position at 12 deg BTDC?
I also looked around the dizzy, where is the bolt that loosens the dizzy shaft so I can turn it?
Belle427 said:
I would try to stick to the existing layout.
On my car, lining up the pointer on the crank pulley at the TDC mark is between 3 & 4 on that diagram, and winding it back to 12 deg BTDC on the crank pulley does not get the rotor round enough to point to number 4 on that diagram.I had wired up my HT leads with the orientation of that diagram when I first got the car a couple of years ago, so it seems I had my number 1 cylinder about 3 terminals too far anticlockwise, although the rest of the firing order was followed and was correct. You would not have guessed that though as the car did not show any signs that anything was out.
Having said that, I also had it running on 7 cylinders once, and had 3 & 5 the wrong way round for a couple of days and it still ran, sort of, 'OK'.
So it looks like I have to take the distributor out.
What's the best way to do it, set the crank pulley on 12 deg BTDC, then presumably undo that nut (looks inaccessible), pull out the dizzy, then where should I position the rotor so that it spins to the correct location when I push the dizzy back in?
What's the best way to do it, set the crank pulley on 12 deg BTDC, then presumably undo that nut (looks inaccessible), pull out the dizzy, then where should I position the rotor so that it spins to the correct location when I push the dizzy back in?
jazzdude said:
What's the best way to get that clamp off and back on again, do I need a special tool?
9/16" spanner (14mm) and a magnet on a stick. lift out the nut then the plate.When you put the nut back on make sure you put it the right way up. It has a recess machined in the bottom so it will sit on the stud whilst you get the thread started.
Steve
Great thanks.
And when replacing the dizzy, once I have the rotor arm pointed in the right general direction I turn the dizzy until the rotor arm lines up with the centre of the terminal for cylinder 1, with the crank pulley at 12deg BTDC and then I should find that when I check it with a strobe with the engine running, it should not be too far out?
BTW the marker that sticks out of the block, does the tdc mark line up with the top edge or bottom edge as you look at it with the strobe, or is there a point that is in the middle of the marker?
And when replacing the dizzy, once I have the rotor arm pointed in the right general direction I turn the dizzy until the rotor arm lines up with the centre of the terminal for cylinder 1, with the crank pulley at 12deg BTDC and then I should find that when I check it with a strobe with the engine running, it should not be too far out?
BTW the marker that sticks out of the block, does the tdc mark line up with the top edge or bottom edge as you look at it with the strobe, or is there a point that is in the middle of the marker?
Gassing Station | Chimaera | Top of Page | What's New | My Stuff