My car ran perfect, then I tried tuning it

[LaGrasta]

My car ran so well, until I brought out the tach, timing light and vacume guage. My problem is it hesitates when I leave the line slowly. If I juice it, it pulls smooth. I have it idleing at about 500rpm, the vacume at the intake is about 18 and the original advance was off the scale like 25. It's now about 12. I had it at 15, but it made no differance, it still hesitated in the same manner.
I originally messed with the set-up because I was hoping to improve fuel milage.

 

[Anonymous]

Here is my suggestion...

Start it up, and warm it up. Make sure it is at operating temp.
Loosen dizzy, and advance the timing until it starts to sputter, then back off just enough for it to smooth out.
Test drive.
Watch the temp gauge, and check for drivability. Retard more if required. (IE knocking, or excessive high temp.)
When you get it where you like it, drive the hell out if it.

Bill

 

[LaGrasta]

That was exactly what I did. I didn't advance it to 25 like it originally was (although maybe I should), but it still had the hesitation.

 

[Anonymous]

25 is right about where mine has it's sweet spot.

Bill

 

[Anonymous]

My 170 runs best with about 25 degrees of advance, too. At factory listed specs its a real dog. --- I agree with the above advice.... warm it up, set the timing as described and then re-adjust your carb to back the rpm's back down a bit. --- Just be sure you don't overheat it or end up with pinging.

 

[LaGrasta]

Wow, I guess I should have left it alone at 25 then. I just imagined that was way too advanced. I'll do that maybe this afternoon. Thanks guys, I'll let you know how it goes.

 

[mugsy]

Sounds like your balancer is off. Which is not that uncommon.

The other way to "guess" at initial timing is to use a vacuum gauge. Attach it to the manifold and then adjust the dizzy until the highest vacuum reading, and lock 'er down there. You can use the vac gauge to set the carb too. Use it for the idle mixture setting.

Have fun.

 

[CobraSix]

Mine runs great at 10-12* Advance. Try verifying TDC on your balancer. Pull #1 spark plug and then rotate the crank by hand until the piston is TDC. See where it lines up on your balancer. I'm will to bet your balancer is off some.

Slade

 

[LaGrasta]

Mugsy, I haven't tried setting my dizzy by the vacume. I could try that today. As far as the balancer being off, I'm lost. I haven't any knowledge of how that works or how to adjust it. I think I'll leave that as a last resort to look at. Ecspecially I've not touched it anyway.
Since the car ran so good at 25°, I'm going to head for that and see how that helps the situation. If that doesn't do it, I'll try Mugsy's idea. If I fail then, I'll come back to the balancer.

 

[CobraSix]

easiest way to adjust the balancer, go to TDC like described (doesn't matter which stroke since it is the balancer), when at TDC, make a mark on your balancer where the O* mark is on your timing bracket. That is your TDC on the balancer now. I suggest using some white out or white model paint so you can see it easier when timing.

Slade

 

[LaGrasta]

I can do that! Thanks CobraSix.

 

[Hot 6t Falcon]

A Hmmmm" question for you guys at 25 degrees, are you disconnecting the vacuum line between the distributor and the carb?

It would be normal to have 25 with it on and about 15 with it off.

 

[Anonymous]

Yes. The vacuum line was diconnected from the dizzy to the carb. I don't use the Timing light, or the vacuum gauge. I just turn until it runs the best, test drive, and adjust from there until I feel the Sweet spot. Then I throw a light on it just for the hell of it to see where it is. (Again with the vac line disconnected and plugged.) I used to use the vac gauge, but why use something when you don't need it. (For me at least.)

Bill

 

[Anonymous]

LaGrasta;
Like 6T Falcon said - pull off the vacuum line on the dizzy before setting your timing. The vacuum advance could make it look like it's at 25 degrees when it's really less, much less.

Also, check for frozen (rusted) spark advancer weights in the distributor. A quick check for this is to pull off the cap and try turning the rotor by hand - see if it moves some, then stops, and snaps back when you let go. The dizzys we all use have open bottoms, which lets in moisture and often rusts the posts where the weights are mounted. When this happens, the weights don't advance with engine RPM and lots of static advance is needed to make up the difference.

 

[LaGrasta]

Yeah, my line is disconected and plugged before timing. My weights are fine too.

 

[Anonymous]

I follow the same procedure as Mustang 66 describes above. -- It may be that my damper has slipped, but I really don't care. I've found that most older engines will take a little more spark advance than what the factory specs list and they will run stronger and more efficient at the same time. -- I do have to admit thought that I was a bit surprised the first time I put a timing light on my 170 and found that I'd been running that much advance! When I turned it back the thing really turned into a dog, so I turned it back and left it.

 

[LaGrasta]

Well, I finally put the gauges away and just advanced it till it coughed, then retarded it a bit. I then slowed the idle back down and it's running great now. I guess "by ear" sometimes seems to be better than "by the numbers."

 

[BIGREDRASA]

Now you're cooking!

 

[CobraSix]

That's why tuning an old car is an art, not a science. If it was by the numbers, it would be science. Each car is a little different. I usually start out by the numbers to get it close, then fine tune by ear.

Slade

 

[Anonymous]

If you are setting timing at 25*, are you sure your vacuum advance is working properly? What is your timing with your vacuum hose connected?
If your basically stock car will not run well at factory specs, it is an indication that something is not working properly. Granted it may run better with more advance, but it should also run well at factory specs. I timed mine by ear last year too because it was not running well at stock settings. I also had pinging problems in the summer. Turns out my vac advance on my Loadamatic distributor was not working. I replaced the distributor with a unit that has centrifugal and vacuum advance.