6 replies to this topic

[thegreenhornet]

Hi everyone. I've been checking out my ignition timing with my new strobe light, but I've no idea what it should be set to. It's a '79 car but it's an A+ block with a pre-engaged starter, ballast ignition and verto clutch. For extra confusion, the cylinder head may be later still, as I was assured when I bought it that it was unleaded.

Haynes says that, for a mid-80s engine with a 59d dizzy, it should be at 8 degrees at 1500rpm for low compression and 10 degrees for high compression - no idea which mine is. Putting the engine code into guessworks says "1st alternative compression ratio".

After checking though, the ignition was set at 8 degrees at 1000rpm (which is the value quoted for the 45d dizzy. It's 16 at 1500). Going by the 1000rpm measurement, I've increased it to 10 degrees and gone for a drive, and it's marginally better at full throttle. There's no noticeable pinking when I labour the engine, as the Haynes book says, but surely to advance it any more would be way too much?

Why is mine so.... advancey? It there a definite way to find out what it should be set to?

[geoff-d]

Check in. Manual what your total advance should be for your Dissy at 3600rpm & set it at that speed.

Then when you reset back to idle check timing again & that will be you answer

[ACDodd]

Ok in these situations you need to determine the actual advance curve you have before you can set the timing.

For this you need a strobe light, measure the ignition advance at idle 1500, 2000, 2500 then in 500 rpm increments up to 5krpm. Wear eye protection and complete this with the vacuum advance line disconnected. Post back the results.

Ac

[thegreenhornet]

Looks like I'll have to wait until I can get an extra person to help me then. Can I not find out what the curve is just from the dizzy serial number?

[ACDodd]

No, because that signifies what the advance was when new not now after significant wear. It us very likely to be totally different by now. The secret to setting up an engine is to know what you actually have not what was fitted. Then making this what you need to get the engine to perform,

Ac

Edited by ACDodd, 30 March 2014 - 11:49 AM.

[thegreenhornet]

Ah I see. I'm guessing that I can't get the revs anywhere near high enough just using the idle screw, so it looks like something to get my dad roped into next time I see him.

Should a 59d dizzy always normally be measured from 1500rpm rather than 1000, as the Haynes book describes?

[ACDodd]

No the timing can be set at any point. The factory choose that point as it gives the most accurate and stable setting with the original advance curve. But now this could be way out.

AC