I think I’ve read most of the timing threads in this forum, tried to so I don’t have to ask again. Here’s what’s going on, the car runs rough at idle, surges and it’s running rich but seems to run fine at wide open throttle. I replace the points, set to 30 with a dwell, and went to re-time the car. Before retiming it I double check TDC number one and it came up right at zero on the tab, when I set the timing the car will take about 8° before top dead center, the book says 12° is it to W 30 455. When I put it to 12 degrees and shut it off, then the car has that too much timing action when it doesn’t want to start right away. It seems to me like it should start up just fine at 12° so any ideas solutions? Even driving it at 12 I have the same problem a rich smell surging at Cruz and just seems like a constant miss. I have put new plugs in it.. before I pull the carburetor and start looking at that I just wanted to make sure the timing and everything was right, and the fact that it will not start right at 12° just seems odd to me

 

Is your vacuum advance working correctly? With the engine running, look down into the carb while at idle and raising the rpm a little, if you see fuel dribbling instead of a fine spray the carb has issues. For your timing, drop it back to 8 or 10 and see if your starting issues go away.

 

I did drop it back to eight or 10 in the starting issues went away right away as far as acting like it’s got too much time. It just seems like at 12° it should not act like that at all..I meanthe book says to use 12 degrees as initial.. however the rough idle, surging and rich eye burning exhaust wasn’t rectified at any timing change.. I will definitely fired it up and look down the Venturi’s and see if fuel is on spray or dribble.. I believe I will pull carb tomorrow,

 

It should be set with the engine idling at 1100 rpm, then your idle speed is reduced to 650 for the final setting. Again check the operation of your vac adv and look to see if your carb has issues.

 

Well my first question is what vehicle is this (year and model)?

 

1970 455 w30 engine, does havea decent cam but not the w30 328 cam.

 

Ok, will do that tomorrow..whether you unplug the advance makes no difference as I have the distributor advance going to ported outlet on carb, zero vacuum at idle.definitely try what you suggest.
Eric, i did put a vacuum pump on distributor, it holds vacuum and moves the plate, that much I know.

 

OK, thanks for the info.

Here's my assessment:

The initial advance number is merely a convenience for tune-up purposes so that you can easily set it to that number and then know the timing curve is within specification.

Initial Advance = Total Advance - Mechanical Advance.

So in order to determine the Initial Advance, first set the Total Advance to 32-36 at 3500 RPM or thereabouts (or whenever the advance stops advancing), and the initial advance will be just whatever it will be. You then check the initial advance at idle speed (for my engine that is 1100 RPM) and make note of that for future use.

I did this on my car with a modified HEI distributor and found the initial needs to be 16-18 for the total to be 34-36.

 

I got it set initial @10 degrees, total 34 all in by 2400. Carb rebuilt, running much better, still a very slight miss..will figure it out sooner or later

 

Ensure you have the A/F mixture dialed in correctly. Adjust each A/F mixture screw individually to highest achievable vacuum; or, (old school) adjust each A/F mixture screw CW until increased RPM is achieved and it begins to bog, then back off the A/F mixture screw until the bog disappears. A vacuum gauge is more precise to dial-in the A/F mixture to highest achievable vacuum. That will then provide the best A/F mixture throughout the operating range of the engine.

 

71 gave good advice.
make sure coke is off.
have someone in drivers seat
hold throttle in neutral at to 1200 rpm
put timing light flash at an inch after factory notch on the balancer. Then see what happens.
you need some adjustments but you need a base to start at.

 

I believe once you change the cam, the factory timing settings no longer apply. So you may need to leave it at 8-10 (not 12). This would make sense as a more aggressive cam (W30) has more overlap (lower effective compression) and therefor can tolerate more advance without pinging and easier cranking. A milder cam than the W30 (what you are using) should need less advance and the higher effective compression will make starting harder.