Daihatsu Skywing (like Mk2 Charade) - Timing Mark Convention? - edlithgow

Is there a "universal" convention as to the meaning of a single timing mark on the flywheel?

I'm thinking it could either be the actual static timing point, or it could be TDC.

The manual I;m using (for a slightly different CB-23 engine) seems to imply its the actual static timing point (5 degrees BTDC for that engine) but its ambiguous, and a bit Japlish.

IF the mark is TDC the static timing is going to be approximate anyway since

(a) I dont have the specification for this engine, which I believe is a CB-22. CB-20 is very similar and is 10 degrees BTDC, CB-23 is also very similar and is 5 degrees BTDC

(b) I don't have any way that I can think of to measure degrees of advance anyway. If I knew the flywheel diameter I could work out an angle-circumferential distance relationship, but I don't, so I can't.

I believe fancy timing lights do this for you, but mine is just your basic strobe.

Edited by edlithgow on 11/05/2019 at 04:12

Daihatsu Skywing (like Mk2 Charade) - Timing Mark Convention? - Oli rag

I'd have thought it would be the timing mark rather than showing TDC.

Have you used your strobe on it to see whether it lights on the mark?

Daihatsu Skywing (like Mk2 Charade) - Timing Mark Convention? - Surreydriver

Just remove spark plug # 1. Rotate engine by hand. Ensure both valves on # 1 cylinder are closed and watch the piston rise on compression stroke. Check by suitable means to get it at TDC and check your Timing Mark......

Daihatsu Skywing (like Mk2 Charade) - Timing Mark Convention? - edlithgow

I'd have thought it would be the timing mark rather than showing TDC.

Have you used your strobe on it to see whether it lights on the mark?

It didn't, but then I've fiddled with it before and I THINK I assumed the mark indicated TDC and advanced it a bit.(or maybe used the piston position as outlined below, possibly a rather error-prone procedure in my hands).

I've set it to the mark meantime. Idles fine. It won't rev much under load without dying, but it was like that before.

It advances when revved (so centrifugal advance is to some extent functional) and when a vacuum is applied to the primary vacuum advance port on the distributor (so vacuum advance is to some extent functional)

I'll come back to it after I've checked out the exhaust back pressure, currently underway.

I MIGHT be able to measure the circumference of the flywheel by sticking a thread to it and then rotating the engine, drawing the thread through the timing port and around the flywheel.

This could give me the degrees - circumferential distance relationship, if i need it.

Edited by edlithgow on 12/05/2019 at 05:07

Daihatsu Skywing (like Mk2 Charade) - Timing Mark Convention? - bolt

I'd have thought it would be the timing mark rather than showing TDC.

Have you used your strobe on it to see whether it lights on the mark?

It didn't, but then I've fiddled with it before and I THINK I assumed the mark indicated TDC and advanced it a bit.(or maybe used the piston position as outlined below, possibly a rather error-prone procedure in my hands).

I've set it to the mark meantime. Idles fine. It won't rev much under load without dying, but it was like that before.

It advances when revved (so centrifugal advance is to some extent functional) and when a vacuum is applied to the primary vacuum advance port on the distributor (so vacuum advance is to some extent functional)

I'll come back to it after I've checked out the exhaust back pressure, currently underway.

I MIGHT be able to measure the circumference of the flywheel by sticking a thread to it and then rotating the engine, drawing the thread through the timing port and around the flywheel.

This could give me the degrees - circumferential distance relationship, if i need it.

is the points mounting plate free to move as if its partly seized it wont advance by much anyway, where the timing mark is concerned you only need to mark crank pulley at piston tdc, and timing cover, then use timing light to see where the pulley mark is in relation to it then adjust accordingly

I doubt you will be very far out doing it like that...in days gone by when people changed pulleys after engine rebuilds that was the way to fix timing problems

Daihatsu Skywing (like Mk2 Charade) - Timing Mark Convention? - edlithgow

The camshaft sprocket has a mark which seems to correspond to the mark on the flywheel.

These are both described as "ignition marks" in the manual which, if one could assume forensically precise use of English would imply they are the timing mark, but one can't assume forensically precise use of English.

I think (and am assuming) that they indicate TDC, since they seem to when I stick a chopstick down the plug hole.

My notes mention a more precise TDC finding method involving rotating both sides of a stop down the plug hole, then splitting the angular distance on the cam sprocket, but I havn't attempted that.

I did the glue and string thing to measure the flywheel circumference. 1 degree is about 2mm.

This engine specs 5 degrees (found an owners handbook in Chinese) BTDC BUT I can't get it to idle below about 1500 (I think the idle needle valve or its seat are damaged). Setting static timing at that speed would seem likely to effectively retard it, so I arbitarily set it at the upper limit of the timing window, which is about 10 degrees.

That'll do for timing for now, I've got other problems

 

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