Not for a low compression engine.  You hear most racers talk about not going past 36-32 degrees total, but those are engines with very efficient chamber designs running 10:1 or higher compression.  The less efficient the chamber is and the lower the compression the more timing it needs.  You have to start the burn earlier to fully burn the mixture.  40-42 degrees is not at all uncommon for an engine like yours.

Thanks for the responses. Good information to know.
You are correct, when I advanced the timing, I could hear the rpm pick up and the engine sounded free. When I took it back to 6 degrees, the engine laboured. That was how I came to mess with the engine timing... On cold start ups with the choke in play, the engine sounded somewhat laboured or bogged down.
I was finding that (according to the timing light) I could even advance it up to 20 degrees and it was idling nicely.
Again, there's always that chance the damper on my car has moved and that is why I'm using my ear as well as the timing light.
I will be changing oil in the next couple of weeks, so I will remove a plug and check that out too.

Inaudible detonation is a quick way to kill and engine, and I'm not saying don't check the plugs, but if you are at a true 40 degrees you'll be fine.  Given how low the compression is, even on 87 octane it would be hard to get that engine to ping.  That's another thing worth noting, what octane gas are you running? 

Toploader - if you think your damper were moving, you should replace it.  However, if the initial timing has remained the same, I would doubt that the damper is moving.  You could scibe a mark across the face of the damper catching the outside and inside of the rubber portion to verify if it is moving.  To my knowledge, once the outer portion moves, it does not move back into place.

GREAT post Toploader!....Alway interested in 'timing-stuff'!
Do you have the lighter advance springs in the distrib?
Light springs and 36-40* total advance really makes these little SBF come alive!!!
To play-it-safe and for the interest of hot rodding why not make you a piston stop(or buyone) and determine TDC on your balancer truly IS...TDC.
Scribe a nice heavy line on the balancer where TDC is and compare it with the numbers on your balancer.
The next step would be to buy a timing tape for a SBF and attach it to the balancer/dampner. That way when using your timing light you will be able to 'SEE' what degree for total timing you have!
6sally6

I will have to look into checking top dead center, thanks.
I did fit the lighter advance springs and adjustable Crane vacuum advance a year or so ago. It certainly adds some giddy up.

I keep second guessing myself on this and keep adjusting the timing. I studied the damper more closely on the car and now have a better idea on the marks.
The damper marks don't go any higher than 30 degrees.
I've now set the initial timing (with vacuum line plugged) to be about 16 degrees. The engine seems to run smoothly at that and the idle speed picks up a bit.
When I check total timing, I can only guess that it may top out at around 40 or 45 degrees? There are no marks for me to be certain.
I checked total timing with vacuum plugged and then with the vacuum hooked up. There was no real difference.
I took the car for a long country drive the other day when I had the initial timing set at 14 degrees and it ran well, with no pinging. With it now set at 16 degrees, I need to check to see if it pings now.
Is using a vacuum gauge another way to check timing? What kind of vacuum should I be seeing for optimal performance?

Last edited by Toploader (10/29/2021 2:25 AM)

I took the car for a spirited drive a short time ago and there was no pinging that I could here. Car seemed to run well too.

Keep in mind when you open the throttle/butterflys the vacuum drops to zero! (that's why you can't really adjust vacuum advance in the driveway)
It is "best" to put some type of limiter on the distrib.(inside with the weights & springs) to prevent it from over advancing and possibly causing damage. At high RPM its sometimes hard to HEAR any pinging or rattling.
Inside the distrib. you should see a slot where, as the weights swing out there is a post inside the slot.
I put a cut off piece of an old push rod over that slot....increasing its circumference slightly...that once the weights swing out (at full throttle) the now thicker post stopped the total advance at 36*. I think RPM used pieces of shrink tube on his.
I would GUESS....40-42* would still be in the safe zone BUTT.......36* total is what most guys shoot for...for safety.
Once you remove the reluctor and the vacuum advance plate inside the distrb.......you should see the 'slot & post' I am talking about. You may be able to tweak the post over a little to limit the total advance to approx. 36*.
Like most stuff on a SBF.....it's trial & erorr.
6sally6

See the 'post' in the slot marked 18L.........you need to make that post thicker OR make the slot a little shorter by welding and grinding
Also.... use the slot with the smallest number (it will be the shortest of the two slots!)
The whole object is to have as much INITIAL advance coupled with the least MECHANICAL advance  to equal the TOTAL advance of 36*

8L = 16*           Mechanical advance
9L = 18*
12L= 24*

Therefore 8L slot (if your destrib has it) would be the best.
  Example...(that would be 16* mechanical + 20* initial = 36* total advance)

Last edited by 6sally6 (10/29/2021 10:15 AM)

BobE wrote:

There are options to create additional timing marks on the existing damper.
The simplest is using the existing timing marks on the damper; take a piece of paper and mark the distance between these marks.  Then, use those marks to further mark the damper.  You can use a file to make small “permanent” marks at those locations.  

Thanks for this. I will use my wife's flexible sewing tape measure and add some more marks with a paint pen. It would be good to get this a bit more exact and take out the guess work.

If I use a vacuum gauge, what readings am I wanting to see for optimal timing and then for optimal carb tuning?