Engine idle and timing

[LASERMAN]

Greetings all!

The car runs great, but I want to verify the timing (I had to swivel the ditributor to get the upgraded alternator in).

The car seems to idle a little ragged at 800 rpm, so I have it set at 1000.

My question is this: The timing should be 0 deg TDC at 750-800.

So if I'm going to run the idle at 1000 rpm, what should the timing be set to?

Thanks!

(1972 Opel GT 1.9L 4-speed)

[BQS4]

You don't use the timing to set idle speed. Timing is just that. The idle speed and smoothness are set through the carb.

[wrench459]

I'm no a big fan of the stock tune-up specs.
I tend to like setting the ignition timing using total advance.

A low compression motor can take as much as 46-50 degrees. While an flat top with an cut down head might be only 36 total.

So you could get 20 degrees initial with an total of 46 and give the smog motor a kick in the pants feel. With only some tinkering around with the dist.springs. But I don't know your motor combination.

[kwilford]

I think what is being asked is "should initial timing be different at 1000 rpm versus 800 rpm?" If the mechanical advance hasn't kicked in, which it shouldn't at 1000 rpm, then the same initial advance can be used. But as Dan has suggested, TOTAL advance is more important than initial advance.

[hrcollinsjr]

Good info in prior posts. I would set the initial advance at no more than 5 degrees! If you want to set it higher you're probably going to need to modify the distributor to limit the total advance as Wrench noted. There are some examples of modified distributors on this site.

Why set the idle so high? Are you going by the factory tach? They are sometimes inaccurate. Unless you have a performance cam or are going to be running A/C, I don't see any reason to run the idle above factory specs, but it's your car. It won't hurt anything, just curious.

Harold

[LASERMAN]

KWILFORD had it right - I wanted to know if the setting was different for the higher RPM.

Everyone who has seen timing done knows that the marks "move" based on RPM. Blip the throttle when the timing light is on there, and watch them.

I am using the stock RPM gauge - all I have right now.

I am at 1000 rpm because the car does not idle smooth at 750-800. It also does not put my ALT gauge into the pos with the lights on at idle when it is set to 750-800.

It might not be 1000 if you say the stock tach might be wrong. I just set it for the lowest SMOOTH idle.

This is a stock engine (as far as I know) with the Weber carb.