Little confused on the timing on my car. It's a L48 that is pretty much stock except a Holley 4150 that the previous owner added. I hooked up my timing light to check where the car was at and could not even see the timing mark. Doubled checked to make sure I didn't get the wrong wire or something but all was good. Started retarding the timing and the mark did drop into view. I should point out I did have vacuum advanced plugged and the idle is set at 600. I brought it down to around 4 degrees and the car would hardly run. So I did as my dad used to do and just listened to the car as I advanced the timing. Once got it where it sounded about right, re adjusted the idle speed and car seemed to be running great. Plenty of snap in throttle and no pinging. Went for a spin and it seemed to run better than ever. So, rechecked with my light stepping up degrees until timing mark was at 0 at idle with no vacuum. Now here's what has my puzzled, I had 42 degrees. I guess you that initial timing. I did bring the RPMs up and did see my mechanical advance of 8-12 degrees. What am I missing? Could the distributor be out of place? Damper slipped? The car is actually running great starts and idles fine.

 

Sounds like a slipped damper. Mine used to show 47 deg at 3000 rpm with vac advance plugged. The black damper is the new one, the white x on the old one is approx where the TDC line should be! Actual timing was 35 deg at 3000 rpm

 

Your Balancer has spun.

Replace it, it's easy.

 

Ok sounds like that's it so now the question, which damper? Seems like there are a dozen to choose from.

 

Just go to the Parts Store and get one, don't over think it.

On my last engine, I replaced my with a Powerbond? (I think that's what it was) from O'Reilly. About 40 bucks. Buy or rent the puller.

It's a straightforward job.

 

That's not right. Sounds like the advance mechanism is jammed. Easy fix.

 

Ok, now 6 3/4 inch or 8? Seems some 4 bolt mains used 8...sorry not with car at the moment or I would measure...just wondering and day dreaming...haha

 

I'm not sure if the L48 came with an 8 inch or not, the L82 did. If it is the 6 inch, I don't think it matters too much going with an 8, as long as it doesn't interfere with the timing tab?

 

Perhaps. Easy to check I guess. Just take off the cap and check the travel of the mechanical advance?

 

Unless he's running super heavy springs... also depends on how far he brought the vacuum advance up.

My friend's 496 was getting about 4* from a 2000 RPM bump from idle... mondo springs. A "light" spring set changed that to almost 20* over the same range.