10.5 compression street strip car , just wondering if having it locked out will clean it up putting around at part throttle.
Any negatives..... Positives....

I wouldn't think so unless you have hot starting issues, most guys like to get into full timing as soon as possible anyway.

I ran my MSD locked out for years, 35* all the time no problem. My ignition was setup so I could spin it over then hit the ignition if I needed to, generally never was a problem.

It did help it run cleaner driving around for sure. I have sence changed and use a megasquirt to control coil on plug ignition. Under light load I have the timing as high as 45* and it runs even cleaner and had a noticeable drop in temps when just putting around at low speeds, any load at all and it drops the timing back down. It uses a map sensor for the load.

My small block is locked out at 32. I've pretty much gotten used to spinning it over before turning the ign on.

Mine likes 32, but won't spin it over first to start it. Shouldn't be an issue..... I hope

IMO, street / strip car needs an advance system and additional advance for cruising around under light load. You will get the best of both worlds. Easy starting and additional advance ( over your total ) for clean cruising and when you jump on it, the additional advance drops out and you run at the mechanical total advance ( just like being a locked out system ). Best of both worlds.

Genuine pre-WWI technology.

#1 reason why distributors are locked: owner doesn't understand what it does.

Mine is locked at 35* and it idles better than before and I have not had any starting issues. It is 10.9-1 comp. and on pump 93 gas.

on target!

So while we are on this subject, how much timing is too much under idle/light load conditions? I was surprised at the temp drop I got once I built an advance curve into my ECU. I haven't tried it over 45 yet. I figured with a 4500 converter and the timing returning to 35* under any appreciable load(and above 3500RPM) I am safe from a spark knock standpoint.

On mine (EFI 496 wedge) idle likes 20 degrees. Light cruise I have set up to 50 degrees advance which is the limit of my system. Otherwise I would have tried 55 degrees. I race it on a road course time to time and have driven it >4,000 miles IL-CA-IL without problem.

the truth! one reason to not lock it out is broken starters. it's very easy to build a fast centrifugal curve with plenty of timing at low rpm, and a vacuum advance can be used too for cruising.

Would you please explain

Using the old school method :)-hook up a vacuum gauge to the intake manifold. Set your idle speed rpm. Then start advancing the timing while maintaining the same idle speed rpm. When you see the vacuum reading start to fall off, back the timing down a couple of degrees and you are there. As far as total timing ( mechanical and vacuum )at cruise, depends on a lot of factors, including the DA, but generally speaking, most vacuum advance units come with about 16* built in them. Soooo, if you are cruising around 3K and your total mechanical is 36* and it's all in at 2800rpm, 36* plus 16* would give you a total timing at cruise of 52*. Very common #'s for your average warmed up street machine. Adjustable vacuum advance units are available for most distributors and they are the way to go. I used to adjust my cruise timing ( with adjustable vacuum pot )by slightly dipping in to the throttle while at cruise. If I could hear a little "tinkling", I would back off the vacuum pot a few degrees - until the noise went away.

The stock distributor mechanism, produced by the tens of millions and as found in any pre-EFI engine since perhaps 1930, anticipates and compensates for engine ignition timing under a wide range of conditions.

The reason why "locked" appears to function reasonably:
1. No valid comparison made (the distributor was never correctly re-purposed).
2. Limited use ("it hardly gets warm").
3. Large initial spark lead more or less imitates much smaller (best) ignition lead + vacuum advance for light throttle, but:
a. It doesn't self-adjust for load conditions.
b. It's only close to what the engine requires, not exact.
c. WOT at low RPM will knock badly.

Typical distributor set-up:
1. Initial lead 15° (mild engine) to 20° (big cam). Anything else may be that strange off-idle carb problem...
2. Auto-advance curve shortened to total (known by best MPH) - initial lead.
3. Advance weight + light springs give full advance by 1,500 RPM.
4. Vacuum advance adds 20-25° degrees under high vacuum, drops out before power valve opens.

I sure am glad I can adjust this with a keyboard now.

Big 10-4 on that!

I cant do that yet... I dont have any timing set up
yet.. I will get a crank sensor after DW or maybe
I'll wait till winter... all I have at the moment
is fuel control

I used an MSD crank sensor bracket and ordered a "universal" sensor mount from them that was blank so I could mount my hall effect sensor.

I set up both my cars with one light spring (the other is removed completely). Since they are cammed together the weights will still move the same way, but now you have full timing at idle. Since the starter spins it slower than that, it is at or near whatever you have the initial set at, so you don't have any problems with it kicking back.