boese1978

First, this is not intended to aggravate anyone or appear obstinate on my part. Many posts relating to this subject and setting the timing swear by timing lights and timing to a certain number. So, I , having a stroked non stock set up, timed by ear so to speak considering there are no numbers to "time it to". What is the difference? I have it set where the engine purrs throughout the rpm range, no hesitation, no back fire, nothing but strong, responsive and powerful. If I turn the distributor 1/16" either way the engine performs poorly, so I have found the sweet spot for my set up and don't know or need to know what my timing is set at number-wise do I?. That being said, if an engine is running fine and any additional adjustment makes it run poorly, why not time by ear?

Merry Christmas and Happy NY to everyone!

oldcutlass

Throw a timing light on it and post your current settings? Just curious, besides its a good idea to make a note so you don't have to experiment the next time you give it a tune.

boese1978

Good point as a reference number. I'll try and get a light on it this weekend and post.

Koda

Settings are repeatable. Also, it's more precise than your ear. You may get better performance out of it still. Top dead center is still where it was on a stroked engine. While the piston position relative to the crank angle may change during the stroke,
the timing tab will be of SOME use, even though 8 degrees may not actually be 8 degrees. However, since you are adjusting the distributor by hand, it only serves as a reference point anyway.

It also serves as a diagnostic. If the car suddenly runs poorly, a timing light attached showing that the timing is now different from where you set is helps you know where to go.

Tuffnut

I as well would be interested to know what the actual timing is at. My 75 350 is no longer stock, with different heads, intake and cam.
My biggest worry is ping / detonation.

Jeff

boese1978

"You may get better performance out of it still "
Please elaborate, as mentioned the SLIGHTEST tweek, advanced or retarded, will make it run rough. Good point on diagnostics.

Fun71

Now that doesn't sound right at all. The engine should run about the same with the timing moved a few degrees advanced or retarded. Sounds as if there's something off with your distributor.

therobski

X2-Fun71 if that distributor is that sensitive I agree or could be "stabbed in" 1 tooth off?

droldsmorland

Agreed 100%. I always time-by-ear and a vacuum gauge. Keep the dist loose enough to road test and bump up or down depending on spark knock and performance.
Of course doing this at 90*F RH 90% Ambient one day verses 50*F RH 35% the next means readjustment...aka more timing. That's why I keep mine loose enough to make that adjustment on the fly. I learned this while living in the Sac-of-tomato valley and then we'd travel up to Truckee or Tahoe. Definitely had to adjust on-the-fly at 7000 feet at the Donner Pass. That mountain air is awesome as long as you're not a Carbureted BB gas guzzlin V8 Olds. It'd run like a one barrel I6 if you didn't adjust timing and A/F. Kept a vac gauge in trunk, still do... **** yep.
Your modern ECM,TCM controls all of this for you now.
ill use a set-back timing light to see where the other two timing events are happening (at what RPM).This is all part of super tuning. Give it as much timing as it will tolerate, period.
Book says something stupid like 4 or 6* BTDC...BAH not..Dont even remember cuz I never paid attention too that.
Factory is well known for under rating everything in favor of the warranty bean counters, insurance lummox and EPA/DOE gooneys.

Im at 14-16* base on 93 Ethanol free at seal level(occasionally a sip of 110, 260!). 12* more on the canister, 12 more on the weights (DUI HEI). On a 95*F day I will back it down to ?? by ear due to WOT knock. Who doesn't like WOT!?!
Using all the senses to tune has resulted in a well sorted out slightly modified 68 400 442. No computer controls just a big silver back with busted knuckles and good ears.

Fun71

So you're running 26-28º total? Wow, that seems about 10º low. I run 36-38 here in 110º temps with 91 octane 10% ethanol fuel.
You must have a lot more dynamic compression than I have to need that reduced total advance.

truckman5000

Think hes saying 24deg. Plus base of 14deg
if that's correct, thats what I run. 1click of the key, fires right up. If ur cranking, and cranking, it's off, or something else

cjsdad

I did the exact same thing back in the mid '80s with my Olds Starfire that had a factory 305 SBC in it. Temp and humidity would change the timing needs from day to day. Just driving from the middle of Sacramento to Rancho Cordova would change the engine output.

Another story that relates involves my first 67 Cutlass Supreme while living in the Phoenix area (Mesa). I had replaced the head gaskets on the 330 and made a quick tune just to get the engine running, then forgot about it. A few weeks later I had to pass an emissions test for registration purposes and failed. I still had my timing light and vacuum gauge in the trunk so pulled into the parking lot after failing and set the timing, dwell, idle RPM, and AF mix. It passed with flying colors in a matter of 10 minutes later. The engine was not running poorly at all, but after changing the settings with accurate measuring tools the engine ran even better and according to the state of Arizona, cleaner!

Charlie Jones

I've seen engines in my career that the balancer had "slipped" so far as to make the mark useless .
The owners of these "clunkers" , of course , did not want to pay for a new balancer .
As a result , I set the timing with a vacuum guage . I turned the distributor until I got the highest steady vacuum reading at idle , and locked it down .
Worked every time .

droldsmorland

Correct, 38* all in before 3K....bout 27-2800.

76olds

I bought a Summit dial back timing light a couple years ago, used it a few times , played with it, pi$$ed me off, then, threw it under the bench. I have always set my timing by vacuum, ear and fun pedal as well. It was a little more difficult with the new DUI distributor I purchased thou, the engine ran darn good where as the rebuilt original didn't in the same position ( very close) . It took a few more short runs to get the DUI unit optimal . My light shows 34* all in a 2800 by the way if that means anything.

Eric

therobski

Dumb question-when you guys use a vacuum gauge to obtain the maximum inches of vacuum at 750 rpm, are you still blocking off the vacuum line to the distributor?

76olds

Not a dumb question at all really, I feel many guys do have trouble with timing set-up and vacuum advance .
I myself,..
Set the adjustable vac can ( this takes a bit of time a real PITA) plug it then set full vacuum. After that, I leave it plugged in and operational , take the car for a few good runs when setting the timing by ear for throttle response. I back it off slightly if I get a hard start condition.
I like to hit the key and run, no cranking.

Eric

Fun71

Charlie Jones

I generally don't bother disconnecting it .
It generally depends on the system . If it's connected to ported vacuum , then it doesn't make any difference . There is no vacuum to the advance at idle , only at part throttle .
If the vacuum advance is connected to manifold vacuum , then it must remain connected .

76olds

I adjusted my vacuum advance can by switching from ported to manifold , this tells me how much advance my can is pulling. Other than this step, I keep my vac advance hooked up driving/ setting by ear.
Seems to work , I haven't detonated the heck out of my 350