442scotty

Judging by the number of times this has come up it must be confusing to many...
Before I had my engine rebuilt I had problems with pinging after changing to an HEI dist. on my 455 so I tweaked the HEI with a crane adjustable advance and put the stock stiff springs in.

My question is....with everything all hooked (including vaccum) up what should my timing reading be...I just fired up my new engine today...appears to run great...I put my gun on it and dialed it back to zero...at 2000 rpm I showed 30 degrees...at 1500 rpm it was around 24 degrees I believe...

What advance readings should I be looking at at 1500 2000 2500 3000 rpm with everything (vaccum) all hooked up.

BosMobile

Hey,I struggled with this as well.After alot of reseach this is a basic ideal.For performance,you'll want 36 total advance,all in by 2500.These settings might vary slightly per application.Whats hard to understand ,is the vacume advance.Vacume drops to zero as soon as you nail it,so the VA does nothing at full throttle.Unhook and plug,the VA hose[stoping the vacume]now check your timing at your forementioned RPMs[afriend comes in handy here]write down the result.Check at idle,then every 1000 rpm or so.As rpm increases,so will timing.It will only advance so far,thats total timing[less vacume,but dont worry with that yet]Now look at your list,lets say your BASE timing is 12degrees.When it advanced to 36[or so] at 3000 rpm.So ''mechanical'' advance[the amount the wieghts move out]is 36 minus 12, 24 degrees mechanical advance,12 degrees inial[what ever you have base or inial timing set to IE;8 BTDC,factory]So if you want performance,use lighter springs,to advance sooner,all in by 2500 or so.Anywhere between 8 BTDC and 14 BTDC should be fine for inial setting.Now hook up the vacume advance,some are adjustable,you could have as much as 50 degrees,with all of it.Inial [12], mechanical [24],vacume [14]dont worry about it,remember as rpm increases,vacume drops.Taking out vac advance.
Hope i didnt confuse you more.I'll be glad to help ,if i can.
OLD COUNTRY BOY WAY,with the engine warm,turn timing up,till engine drags when cranking.Then bump it down till it doesnt drag.Go for a drive,nail it,if it pings[youll know]back it down .till it doesnt ping and cranks easy.Your DEAD ON!!
MAY NOT WORK ON CITY CARS

442scotty

Thanks..will give it a try

scrappie

Wow! my head is spinning after that explanation.No offense.
I worked at a garage after high school. and the old timers use to set timing by having someone in the car with the engine warm and running, that person would put it in gear with foot on brake and "torque up the engine at a constant rpm" The other guy would be under the hood with the distributer loose and would advance the dist. until engine starts to ping and then back off a bit. It use to be pretty close. Other guys just open the book and put a timing light on it.

BosMobile

Hey,no offence taken.Looks like i should've went to bed!

jensenracing77

i understand it.

BosMobile

THANKS,i tried.BO

442scotty

Ok...here is where Im at so far...I set the initial advance to 12 degrees...anymore and she wanted to keep running when I shut her off. I unplugged the vacuum advance at ran her up to 3000 rpm...timing showed 27 degrees...So I will start with this...from an old 1975 olds manual this seems about right for a 455...

I will take her out next week and she how she performs them adjust the new edelbrock carb and timing accordingly...Hope it doesnt ping because Im ping deaf...Got my fingers crossed...

BosMobile

Hey,keep researching!I'm new to computers,but i've found it a great tool,for learing about cars.Here's one good link
http://www.460ford.com/forum/showthread.php?t=117504
this guy is an gm enginer.Check it out,later,BO
sorry about the ford,but helps where you find it.HA HA