VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 29 spark timing

When I had my engine rebuilt 600 miles ago I set the spark advance according to the recommendations and "tune up specifications for an early 30's Chevy" which I found on this site.
https://1931chevrolet.com/specs7index.htm
I made sure the advance was set at 18 degrees. BTC when the engine was not running. Lately I thought the engine seemed too noisy when climbing hills at around 45 mph but quieted down when I pulled the spark retard but lost power, so I purchased a timing light (Innova 3555 Advance Timing Light) and checked the timing with the engine at idle. It turns out that the timing was way too far advanced. I assumed this was due to the distributor automatically advancing the spark when the engine is running. I followed the instructions in the repair manual and using a test light I set the timing at 12 degrees advanced (engine stopped). Then I tested it with the engine running and with the timing light it read 18 degrees advanced at idle. It seems to run quieter on the hills with this setting but may not have quite as much power I'm not sure.

I may be confused reading the VCCA instructions. It says "CONCLUSION: Time it at 12 degrees advanced (noting the mark on the flywheel), with the spark knob pushed all of the way in. After you get the car running, then bump the timing to 18 degrees, and make sure that your AC spark plugs are gapped to .040".
When I set it at 12 degrees when not running It automatically goes to 18 degrees when running.
Has anyone else noticed this? Do you set the timing at 18 degrees with the engine running or when stopped?
At what RPM should the distributor start advancing?

the 18 deg is nominal , I found out that my 1929 is happiest at around 15 degrees advanced. runs good smooth strong.

also tweaked my spark gap so it ran smooth as well. my engine was rebuilt and is .040" over and now starts and runs like a champ all day long !!

here is the advance numbers from the cheat sheet I have for the 1929 Delco-Remy 633G Distributor, Chip & JYD can validate since they work on these things

Hello Bare Feet,
A VCCA post by CJP'S 29 08/11/10 04:58AM #180437 states: The centrifugal advance figure for Delco-Remy distributor model 633-G are as follows:

Advance starts at 700 engine rpm's with 2 degrees advance
At 2,000 engine rpm's,advance is 25 degrees
Maximum centrifugal advance occurs at 2,600rpm's and is
31 degrees.
I'm thinking that if your static (engine off) timing of 12 degrees, automatically moves to 18 degrees running (engine on) at idle RPM, something may be amiss within the centrifugal advance mechanism. Broken,loose,weak or missing springs maybe? Let us know what your idle RPM is set at. I believe, after the static timing is set, all other timing adjustments are made with engine running. If you have time to read, take a look at all the VCCA posts given to BearsFan315 1929 Engine Timing/Tune-up (Plan of Action) 06/19/13 10:01AM #281335

Thanks for the "cheat sheet".
Do you set the 15 deg with engine running? If not, then have you checked it again when idling to see how far it advances.
I am wondering if my distributor is advancing too much.

Hello Bare Feet,
Did you see my responding post? It may be some help.

Harry sorry
I couldn't figure out how to narrow the search engine to 6/19/13. I did get to August 5th. 2013 and found a discussion about spark timing with Junkyard Dog and Bears Fan. I have tried in the past but cannot find posts by number. When I try searching by newer than 12 years and older than 10 years I can't get to the exact date. It seems to limit the results to 200 and only goes back to 8/01/13.

If you are searching for Bearsfan "Plan of action" it`s here: https://vccachat.org/ubbthreads.php/topics/281335/1929-engine-timing-tune-up-plan-of-action.html

Hello Bare Feet,
Well, I don't use the search engine. I usually have luck doing a Google search regarding a topic. With your post, I typed: 'How to properly time a 1929 thru 1932 Chevy six engine.' VCCA posts and others appear where you can usually find what you're seeking. I would think that the VCCA search feature could find a particular post if someone gave you the post number but I don't know for sure.

Thanks Morten
Thats good information.
It runs good now, but I may tweak it on some test runs.

I set my rough timing engine off per the VCCA specs, then i tweaked it from there. the rough settings got it running.

after engine warmed up, i adjusted carburetor to get the idle down then tweaked timing so that the engine would idle smooth with no sputter or back fire (putter or missing) out the exhaust. then revved it up and checked again. drove it and tweaked it, and now it idles smooth, runs strong, and no sputter or miss. i went back with my timing light and it is around 15 at idle warmed up. My old school meter does volt, dwell, and rpm :) works great on these old Chevrolets :)

also per the info the idle is around 300 rpm, mine settles around 400-450

true tuning is done by ear and feel and done when the car when it is happy, the numbers are just reference

Thanks BearsFan315