Internet searching has shown the 41 weights and 375 center to be some sort of magical formula for a great timing curve. This is supposed to give you about 35ish total running 12 initial. Yet on Olds specific forums everybody seems to recommend running lots of initial timing ( 20+ ) but still around 36 total.

So what am I missing? Is it that Olds engines specifically do better with lots of initial timing compared to Chevy's ( which is what most people are probably referring to on other forums/magazine articles ) or what?

I'm currently at around 12-13 initial and 35 all in at around 3k. That's pretty darn right on that 'magical' 41/375 combo yet the people in the Olds world are telling me to run 20+ initial all in before 3k. This is a lot more aggressive than what everybody else recommends.

 

When doing research, try to compare apples to apples.

My guess is, that most people suggesting 20 degrees are using the garden variety HEI,(low compression) which probably doesn't have 41/375 combo.

The more compression your engine has the less initial timing it will tolerate.

You have to tune what you have. Its not plug n play.

My experience is, you have to tune what you have. Use all other info as a guide line, not something set in stone.

 

Certainly need to tune what you have but you need a starting point. When the experts tell you to do contradictory things though it certainly makes things a lot more difficult and confusing.

So do Olds engines in general like more initial timing vs say Chebby's ( with similar build ) thereby validating the Olds guys saying to run a lot more initial vs the 'magical 41/375 combo being constantly recommend on other forums?

 

It's not an Oldsmobile thing, the timing numbers are a general rule of thumb for all V8's. Where and how the timing curve is set is dependent on compression, cam profiles, altitude, fuel quality, and application.

Most people set their timing for the 36ish mechanical and let the initial fall where it may. I don't see how magical the numbers are on the weights and center as there are hundreds of different sets that have been used on different engines over the years.

Does your engine run and perform better with the setup you have now vs the previous?

 

GM had to sell cars in Miami and Denver.

The ignition curve had to work in both conditions. Meaning, v8 engines like certain timing windows to work within.

GM gave you the starting point.

Magical is subjective, until a dyno says otherwise.

 

In the interest of trying to help, try different carb settings/jets.

 

What exactly are we discussing? The chevy 307 had 9 to 1 CR, the Olds 307 7.8 to 1 CR. HEI or points? If you want a real kick-azz ride, lock the timing at 38 or whatever and get a start-retard box, OMG!!! Part throttle response is awesome! Timing curves were designed to adjust for easy starting and a multitude of applications, as Don suggested.

 

I had a Moroso HEI Advance Curve Kit in my distributor and it gave 24º mechanical, so the initial was 12º for 36º total = practically the same as the factory points setup (10º initial, 24º mechanical).

Many folks said a higher initial setting gives more off-idle torque, more idle vacuum, and a smoother idle. I put the factory center bar and weights back in (18º initial , 18º mechanical) and sure enough, it idles smoother, has more vacuum, and the RPM doesn't drop when I put it in gear or turn the AC on.

So for my engine, the higher initial is a plus.

I should say with the 18-20º initial the engine sounds smooth whereas with the 10-12º initial there is a noticeable lope.

 

Fun71, what centerbar and weights are you using? Are you running vac advance?

 

Sorry I posted 18/18 as that is what I keep remembering when I was playing around with different springs, but the measurements I have in my notes from that time are actually 16/20. When I set the initial to 18 I probably had 38 total - I was doing a lot of experimenting then.

I looked up my notes and posted the info in this thread:
https://classicoldsmobile.com/forums...enterbars.html

Weights stamped 139, plate stamped 446

 

Yeah it's good to see real world timing numbers people are getting with their different center/weight combos for reference.