So I have been reading alot of posts lately on engine damage and too much timing could be the factor.
My question is how much intital timing (at idle) would be too much for the motor to take.
Also I have read online many hours on how to properly set timing and different types.
If I read correctly stock engines need less intitial timing around 10* btdc and engines with hotter cams call for more.
I have also heard with aluminum heads you can run more timing.
Is it normal for an engine to run 14*-16* initial timing? When I run less than 14* initial the car will not take off from a stop properly due to high rear end gears putting too much of a load on the motor, i'm assuming...
Also I find it very hard to set timing as it jumps around sometimes it goes down to 12* then to 16*

Engines get damaged under high load. This could be at WOT,, 6k thru the traps, or it could be pulling out to pass on a 2 lane without bothering to downshift, at 2k or less.

Engines do not get damaged sitting idling, unless you forget to add oil or coolant.

I have no idea why the factory speced so little timing in the 60's. In the 70's it was to reduce NOX emissions.

At idle, somewhere between 24 and 36 degrees is good. Most of the time, you need vacuum advance on manifold or completely locked out timing to get that.

Most motors want a max of 32-38 under maximum load.

high load under 2k may want less than 20.

If I read correctly stock engines need less intitial timing around 10* btdc and engines with hotter cams call for more.
The reason hotter cams require more is they work very insffentently outside there rated rpm range, which results in a very rough idle at low rpm. its just a mateer of engine dynmaics
This can be compensated for by idling at a higher rpm, and or increasing the advance.
Even a quite 'hot cam will idle at low er rpm and a lower advance fine, but it will be a very loppy ubstable idle, and when take off the extra gas/load under near nil power (becuse it has less power than a stock at low rpm above) it is likelt to stumble or even cut out, espec if a auto.

How much timing is also influneced by the dynamic compression and the type of fuel.
eg a hi octane LPG engine with a hi 10 or 11:1 compression ratio with a lumpy cam will idle quite nice and stable with about 8 or 10 deg, and 400 rpm in gear on a auto and 450 neutral... then plant the foot and have no stumble or hesitation.

As Jim says mst stock or near stock internal compustion engines require between 32 to 38 deg under load, thu increasing compression this reduces.

Running too much advance increases NOx emissions with a slight drop off in power.
Not enough advance results in a sudden drop off in power once the 'cut off piont' is reached.
The basic secret is establish this 'cut off point' at a given rpm...ie 500 rpm increments from idle speed up to when the curve is all in.
Then if the idle is still to rough, unstable, ad vac advance from manifold vaccuum, so the engine fires without labouring, once fired the vac advance kicks in and adds the extra advance to the curve.

When I run less than 14* initial the car will not take off from a stop properly due to high rear end gears putting too much of a load on the motor,
If the vac advance is in, and u take off slow keeping the vac advance fully activated u will find it ok...but press the throttle further the engine is not responsive..
upping the intial is a quick fix, or lighten the spring weights, so they hold in at idle speed but come off faster.

Also I find it very hard to set timing as it jumps around sometimes it goes down to 12* then to 16*
This is a sign of worn dizzy bushes, to much end play, worn weight bushes, a dizzy in need of service/rebuild or replacement.
Dizzys are a very high 'prescission instrument'... the spark has to hit the cylinder right on time (generaly firing the max explosion point about 15 deg atdc ) now thinkabout how fast those pistons are going and to get it to fire spot on time, measured in fractions of a milli second.....and do so 1000s of times every minute for yrs on end...
If u take a 4 cylinder car say 100hp and using only 10 hp cruising, 1 in 4 fires is only working at 50% effecency, u have just dropped to 8 hp...and under full load only have 85 hp.
I hope u now understand how important the curve and amount of advance and when, and having a dizzy in top condition...has a huge effect on power and economy.

This might sound alittle loose but owell
I try setting timing at idle for years and does not work for me.
I run engines for years and this is all i do.
Rev engine to 3500 , move distributor till engine runs smooth , no missing and sounds healthy. Then set your idle and mixture. Drive away.
I do not use a timing light.
2500 RPM is about my breaking point to load engine when accelerating.
Below this your engine pistons are hard on the cylinder walls, under load.

Out of interest, what does your total cent end up at?
And how much dent advance is there in your dizzy?
Setting idle timing like that ends up with over advanced total...a very common backyard mistake.

Could his varying timing be caused by the cam walking in or out?

alan

Here is what the papers on the distributor say it's a pertronix hei equipped with the silver springs.
500 rpm 0* 1,000 rpm 9* 2,000 rpm 15* 3,000 rpm 19* 4,000 rpm 22* 5,000 rpm 23* and no more advance after that.

On this sheet it also says "adjustments to vacuum advance are made through the port on the front of the facuum canister, The vacuum advance is pre set to 16*. Each additional turn clockwise will add 2* of vacuum advance."

I have tried to put a wrench on the area on the canister and all it does is bend the vacuum canister, don't most vacuum canisters have a plave for an allen wrench?

Hope this helps you guys.

Only until she chew's on me so much that I just pass out!

pdq67

I have tried to put a wrench on the area on the canister and all it does is bend the vacuum canister, don't most vacuum canisters have a plave for an allen wrench?


I think the adjustment is down inside the canister, reach through the vacuum fitting. Take the vacuum line off and stick your tool into the hole.
Now I feel dirty...

Only until she chew's on me so much that I just pass out!

pdq67
That doesn't make any sense but I think I get what your trying to say.
Give me a break i'm 17

Ah, you are just a pup!

He, He!!

pdq67

The flats on the outside of the vac canaster are not for a wrench. Put your 3/32 allen wrench into the port hole feel around and it will slip in and have a slight drag when turning. Clock-wise adds timing cc-wise removes it. (your adjusting a small mechanical stop.)