C-1 Ignition timing

[Richard P.]

I started my '61 on the test stand tonight. Its a stock 230 hp 283 with the exception of an L79 camshaft. It idles comfortably but the ignition timing looks to be about 30 degrees advanced. Does this cam need that much or would the distributor being a tooth off give an incorrect reading on the timing light? Or could it be something else? Thanks in advance.

[Verle R.]

Re: C-1 Ignition timing

Richard,

Is the 30 degrees initial or total mechanical or total with vacuum hooked up timing?

I expect 30 degrees initial would make it difficult to start.
30 degrees total mechanical is too little; should be more like 34.

Did you disconnect the vacuum line, plug off the carburetor end to stop the vacuum leak and then check the timing?

What is the idle RPM?

Verle

[Richard P.]

Re: C-1 Ignition timing

Verle,
There is no vaccuum hose on it yet. Carb is plugged. Distributor is moved while cranking engine to start it. It won't stay running when you retard timing toward normal book setting.
Thanks,
Richard

[Verle R.]

Re: C-1 Ignition timing

This may be a remote possibility but check to make sure the timing mark is in the right place on the balancer.

Verle

[William C.]

Re: C-1 Ignition timing

The L-79 cam in a 283 will change the idle parameters quite a lot. What rpm are you looking to idle at?

[Richard P.]

Re: C-1 Ignition timing

Engine is idling at probably 1000RPM. Thats a guess. I set the engine at TDC before putting the heads on and timing mark is correct. Still puzzled. Thanks.

[William C.]

Re: C-1 Ignition timing

You have only three possibilities that I can see, first, did you check the alignment of the timing mark on the damper to verify it meets tdc whicle assembling the engine. Slippage of the outer to inner ring is not unfrequent on old dampers. Secondly, if the timing mark is ok, then you are actually running 30 degrees or whatever at your "comfortable" idle speed, has the distributor curve been verified such that you know what the dist advance should be at a given rpm? Third, have you set the initial timing while cranking the engine without stating the engine? That is an important number to know if trying to understanding timing at a given rpm. Next, have you hooked up a tach to see what the idle speed actually is? If you know the initial timing, know the distributor curve and know the idle rpm, and they all correspond to your expectations, then you should hook up a vaccum gauge and your vacuum advance, and see what the result is. A note on this is that the vacuum at low rpm with the larger can may not be sufficient to activate the vacuum can unless you vae used on of the low vacuum versions.