From what I understand; total timing of an engine works as follows:

I have the 13L cam in my stock distributor. At total advance I would double the 13 to get 26* of advance.

Add in my initial timing of 8*BTDC and I get 34* total timing.


At 8* initial; I'm getting 37* total timing??? This doesn't add up. I did disconnect the vacuum line to the vacuum advance before checking timing.

Any ideas?
Thanks!

 

Possible the vacuum advance is dirty and sticking a bit in distributor. WD-40 works well for use in the distrbutor. Comes in handy for drying one out if it gets wet too.

 

Brand new vacuum advance that appears to work correctly. Get the same total timing with old vacuum advance as well.
Thanks!

 

Is the Cam gear on the distributor worn, that would cause excessive play!

 

Also check for slack in timing chain.

 

I should be able to feel this by twisting the rotor back and forth; correct? Engine is new.
Thanks!

 

The fact it is a new build, new parts should have been mentioned. Not knowing what engine etc, makes your question kind of hard to answer. Some cams are degreed advanced or retarded. Any play/slack can be seen by turning crank by hand back and forth, watching rotor button to see how much it takes to move it.

 

here is a little reading that might help you out a bit!


Timing Tips for Ford Distributors

 

Engine timing advance works with many different things to achive the acureate amount. There is the base engine timing you set with a timing light. if im not mistaken i think our FE engine base timing is set at somewhere around 2-6 degrees before top dead center.

There is also centrifugal advance this atchived with wieghts in the distributor attached to springs that move out at high rpms. this is usually 10-15 degrees on most destributors. this can be checked by removing and plugging the vacuum advance and having the timing ligh hooked up and revving the engine to 2k rpms and rechcking timing. your reading here minus your base timing is your centrifugal advance.

And there is vacuum advance. This is actuated from the vacuum diaphram on the distributor. not sure what kind of vacuum should be here. I think its venturi vacuum, correct me if im wrong, culd be manifold vacuum. But another thing you should check is the vacuum advance diaphram for the "stop." this is a small peg inside the diaphram that stops travel of the rod that could cause too much advance. vacuum advance is checked by revving the engine with vacuum advance hooked up to 2k. this measurement minus base and centrifugal is your vacuum advance.

easiest to do these measurments with a digital timing light. almost impossible to do with a regular light. the light should have buttons that adjust the blink of the light to different degree marks relative to the light and degree adjustment on it

and yes play in the rotor back and forth is bad.

hope this helps!

 

I'd just adjust base a little more to say 10-12 degrees. And its going to run a little funkey until you give it the beans anyway cause your not building good enough vacuum for the vacuum advance to work anyway. even at idle it does work a little bit. this adjust ment in base timing compensates for that. thats why guys with vacuum boosters and engines with cams have to have a vacuum reservior cause the vacuum just isn't there as much as it would be in an engine with the stock cam. Like i herd a guy at work say when it comes to cam shafts.

You pick it, I'll stick it, and you're stuck with it.

 

Just found that link. Thanks!

 

I'm building excellent vacuum. Engine is stock.

 

Please re-read my original post. I stated what my mechanical advance is. I have the 13L distributor cam which gives me 26* of mechanical advance.

 

You can increase, and decrease overall timing to a small degree, by adjusting the vacuum advance pot, if you have an adjustable vacuum advance. Increasing will cause the vacuum advance pot to pull in more advance sooner to compensate for low vacuum. adjustment is done in most cases with a 3/32 allen wrench inserted into the vacuum port, that the hose attaches to. Clockwise turns increase the advance, and counterclockwise will decrease the advance! This is best done by feel on a a low RPM pull, in a higher gear AKA under load...


If you are set at the proper timing at idle and it is over advancing at total advance, try backing the vacuum pot off. If it is pinging at full advance, adjust it, if it is not pinging don't worry about a degree or two

 

Ok, got your pm. Now we know you have the metal tab in the 13L slot for 26* of mechanical timing. You say you set initial timing at 8* on the damper but have 37* total. Now did you run the engine up to at least 3000rpm while putting the timing light of the marks? If so and that yielded 37* then I could see a couple of things. It is possible the damper has slipped a little and you have 11* initial. Or, when you looked inside your distributor at the lower plate to see the metal tab in the 13L slot, did the metal tab have a little rubber sleeve around it? That sleeve limits the movement of the tab and is one way people can control mechanical advance in engines other than Fords. Mopars are a classic example as their distributors were set for 30* mechanical with no other options. Mine has the sleeve which you would need to be able to get near 26* mechanical and not higher.