I have about 100 miles on the rebuild and its a 40 over 350, The deck was cut and so were the heads. Running a VooDoo cam and headers.

I set the timing by the recommendation of the manufacturer about 12 degrees.

The car ran pretty good but seemed to not be "happy" It just did not pull hard

I put a vacuum gauge on the manifold and timed it by vacuum- like my uncle taught me in the early 70s. I ended up putting a little more timing in car and wow..huge difference.

Anybody else time with a vacuum gauge? why or why not?

 

I use a timing light. Far more accurate. How do you know that you have ~36* total mechanical advance, which is considered optimum, using a vacuum gauge?

 

Simple addition, by adding the known mech advance of the distributor.

 

I have a 60103 voodoo cam in 355 engine, 180cc rhs iron heads. 9.5 to 1 compression. Currently running 22 deg inital timing with 14 deg mechanical advance and 15 on the vacuum advance to maniflod vacuum. I had to fab stops for mech and vac advance to acheive these numbers. No pinging under load and the engine runs happy.

 

I'm interested!
Could you detail the procedure ???

 

What did you do to adjust the stops on the mechanical advance? I use a crane vacume advance which is adjustable for the amount and at what point the advance starts. For the mechanical advance the only way I can see to limit is to grind the points off the center piece? Is it trial and error to get the amount of mech advance you want?

 

You sometimes may need to grind or fill the mechanical advance slot beneath the weights to get the mechanical advance set to where you want it. I had to TIG my slot up and file to set mine. 16 initial, 21 mechanical for 37 degrees at 2,350 RPM and 15 degrees vacuum advance from a B28 can.

 

Are you suggesting we don't need timing lights to accurately time an engine?

 

Manufacturer of what?

Setting timing by vacuum is about as imprecise as setting it by ear.

 

I've been doing it for years or I keep bumping up the timing until I get pinging under a light load, then back off 2*. If it happens at WOT I'll use a recurve kit.
It makes a world of difference if you really run your car. The right lane putt putters will never know, so staying with the book specs is just fine for them

 

I like the vacuum gauge way, than I check with the light and see if its within reason.

 

I strongly disagree.

 

I also strongly disagree. !

For 34 years, I have seen many set timing with a timing light, with a vacuum guage, and I have seen many time by ear. Once about 6 of us stood around this guy Mark's nova with a big block, He timed it by ear and was ***** on accurate with a timing light. Some if back in the day perferred to spend what money we had on a bigger cam or carb, than spend money on a timing light.

 

I use a vacuum gauge. Also..ALL vacuum supplied components ( headlights, wiper door, HVAC and power booster) and been plugged off. As timing light can be useful.. BUT you are ASSUMING that the mark on the outer ring of your balancer has not spun. I have encountered numerous harmonic balancers that have had the outer ring NOT be "clock" in the correct position....as much as 2 inches. SO...FOR ME...trusting the timing light is pointless. Vacuum gauge is more reliable to "real world" requirements for the engine...depending on the engine.

DUB

 

Would one of the proponents for a vacuum gauge describe how you set your total timing ACCURATELY to say 34*?

Hey Lars, did or would you set your timing on that super charged engine you just built with a vacuum gauge and then go out and wind it up to 7K?

 

How about I ask you a question first? Even with your 34* timing (which may be accurate, but not necessarilly correct for your engine), what does that have to do with what the engine needs at idle and any RPM/Load point that is not >3000RPM and WOT.
Only a lazy person or a fool times his engine at high RPM WOT, and neglects those speed/load points where the engine spends 99% of its running life. Unless you have access to an engine dyno to set your timing (and few of us do), a vacuum gauge will give you valuable information on what correct timing numbers your particular engine desires.

It's physics. Don't argue with it.

 

[QUOTE=resdoggie;1584745389]Would one of the proponents for a vacuum gauge describe how you set your total timing ACCURATELY to say 34*?

Hey Lars, did or would you set your timing on that super charged engine you just built with a vacuum gauge and then go out and wind it up to 7K?[/QUOTE


I am sure Lars has the talent and experience to time an engine by many methods including the infamous timing light, a vacuum guage, by an ear of wisdom. and last but not least rubbing two sticks together with enough force, the distributor moves into perfect position. This is the second recent post that I have read that has brought Lars into the final say so. There are a whole mess of mechanics out there with lots of talent and experience and they are on this website and many others sharing their abilities with others and go back to the days when some equipment was just not availible for anyone.

 

I'm interested.

Now that you have it running how you like it, put a light on it and see what it ended up at.

What is your final initial timing and what is your final total timing?

 

Stop with the hey Lars can't you speak for yourself.

 

Please remember, a timing light (if marks are correct, etc.) measures timing at various rpm levels. That does not mean the timing is correct for your engine. Heck the factory gives you a stock setting, which ain't right a far as I'm concerned.
A vacuum gauge tells you what your engine likes.
I have to experiment due to crappy CA wanna-be premium, iron heads and high compression 60's engines.

Here's a post:
http://automotivemileposts.com/garage/v2n8.html

Here's 1 way:
CORRECT SETTING OF IGNITION TIMING WITH VACUUM GAUGE
Connect gauge to intake manifold. Start engine after jacking up rear wheels just off floor. Set throttle stop screw until speedometer shows 14 to 15 M.P.H., no more. Hook up Vacuum Gauge on distributor side for convenience, loosen dis­tributor lock plate screw. While watching Gauge, turn distributor body which­ever way it has to go for retard, until hand indicates 16" or 17". Then, turn distributor body in opposite direction to advance until hand reaches its highest point and begins to fluctuate ahead. Hold it at this point for an instant, then turn distributor body back again very easy, just enough to remove the bounce or fluctuation, thus causing the hand to remain perfectly steady. This is the best point of setting. Lock distributor plate lock screw on side. This allows very close ignition timing setting without "ping" or knock. A road test will then definitely prove the setting is correct.
If the motor is in perfect condition, the hand of Vacuum Gauge will remain steady between 15" and 21".
Altitude has a definite effect on Gauge readings.
At sea level, the Gauge will read approximately 19.5".
For each 1,000 feet above sea level, the Gauge will drop one inch.
Example:
At 2,000 feet the Gauge will read approximately 17.5".
At 5,000 feet it will be 14.5", and at 10,000 feet it will be 9.5".