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I have researched timing on the net and gotten conflicting and ambiguous info. My question is: if the engine is at TDC on the timing light and one is trying to achieve 6-7 degrees BTDC, do you advance or retard from TDC??

And am I correct in my thinking that retarding the timing will slow the engine down and advancing it will speed it up???

This may sound very neophyte but I can't get a straight answer via my Shop Manual, nor Googling the question online.

Thanks to any who are willing to read and respond. Merry Christmas to all the Packard folks out there!!

Retarding/advancing timing have nothing to do with engine idle speed. Idle speed is adjusted as needed with the idle speed screw on the base of the carburetor

I want to help, but now I'm over thinking it. I originally thought retard.

I was thinking retard so it would be BEFORE tdc, but then I started thinking advance because that would advance the timing before you got to tdc.

So honestly you should just skip my post lol!

If you have your timing set at tdc with the engine running you will find that the engine will speed up noticeably as you advance the timing to the correct position of 3 to 5 degrees BEFORE tdc.

If you move the distributor in the opposite direction and for some reason end up with the timing 3-5 degrees retarded, or AFTER tdc, you will have a very warm engine with no power.

Perhaps the terms are confusing: the spark must occur in ADVANCE of the piston reaching TDC on the compression stroke so that the fire has a chance to get going and push the piston down on the power stroke. If the spark occurs after tdc much of your power goes shooting out the exhaust valve when it opens. In addition, the faster the engine is running, the sooner the spark has to come as it takes a finite amount of time for the fuel to burn. That is why distributors have advance mechanisms.

I stand by my post, #7, on your original thread about this car.

Quote:

-> post #7

Quote from post 1 above:
" ... engine is at TDC on the
timing light and one is trying to achieve 6-7
degrees BTDC, do you advance or retard from
TDC??"

Answer: ADVANCE.

Also:
" And am I correct in my thinking that retarding
the timing will slow the engine down and
advancing it will speed it up???"

Answer: True.


But so what????
It is not clear to me why u are considered about "speeding up" or "slowing down" the enginee by ANY means of setting ignition timing.

Let me put it this way:
Setting idel speed of engine is done by a screw on the throttle linkage at the carb.
Setting timeing is done by timing marks. The two tasks are not related.
Have u found the timing marks on the engine???

Agree with Ross on his advice.

Setting the ignition timing and engine idle speed is a back and forth process. First set the engine speed to the specified RPM. Adjust the timing to the desired mark. If engine speeds up or slows down re-adjust, then re-check timing. Repeat until timing is at desired mark and idle is at desired speed.

It is a good idea to disconnect and block the distributor chamber vacuum line when doing this job. Reconnect when finished and do a final check of timing and idle.

Also, a good time to check the chamber for a leak.

Go for it!

(o[]o)

Thank you to all who responded. I believe I now have a clear path forward to 'get it right'.

Re the idle speed comments, I asked this because it is hard to see the timing marks on the flywheel when using a light. They may be marked with some indication as to BTDC or ATDC, or with a '+'or '-', but I can't see them, and wanted some positive way of knowing which way was retarding and which way was advancing the engine. From the comments received, this is now perfectly clear.

I was surprised by the ambiguity on this question; I asked my 90 year old Dad, who was a real car buff back in his day, and he said 'retard', as did a couple of other folks whose opinions I respected. The retired licensed mechanic obviously agreed with 'retard' as this is what he did when setting the timing and, at the end of the day, this could end up being my whole problem on the car stalling. Also, I remember when seeing mechanics time engines when I was a kid, and the engine always seemed to slow down when the correct setting was achieved, so that seemed to endorse the 'retard' vote. I am not yet wanting to do handsprings or anything, but do feel I have uncovered a glaring error that just MIGHT be the solution to a very long standing problem!! Thanks again.