Timing Curve?
Thread Starter
Burning Brakes
Joined: Apr 2013
Posts: 1,072
Likes: 61
From: Saint clair shores Michigan
Timing Curve?
I'm getting ready to put my 77 stroker on a Dyno. Well what I'm wondering,is it worth it to advance the distributor? Will it hurt the engine? How much more power will it give me?
Thanks John.
Thanks John.
Melting Slicks
Joined: Jun 2011
Posts: 3,116
Likes: 598
Dyno tune should cover everything from fuel --- timing.
if just a few runs You could change the timing for each run and see how it effects each run.
Team Owner
Joined: Oct 2004
Posts: 81,241
Likes: 3,063
From: altered state
St. Jude Donor '05
know anyone with a sun machine? More isnt always better.
Tell us about your car..engine, heads, cam, compression induction trans rear gear etc.
Some like a slow curve, some want more total, some lots less.
The engine that runs best at 30 deg will hurt itself on 36.
Youll have to mess with it.
Tell us about your car..engine, heads, cam, compression induction trans rear gear etc.
Some like a slow curve, some want more total, some lots less.
The engine that runs best at 30 deg will hurt itself on 36.
Youll have to mess with it.
Le Mans Master
Joined: Sep 2013
Posts: 6,192
Likes: 750
From: near the thumb in the mitten
Are you dyno tuning it yourself or having it done? Experienced operators will have an idea what to do. The distributor uses weights and springs for the mechanical advance. How much and fast it comes in can jave a big effect. Then vacuum advance for total. Some tuners will not use the vacuum advance just mechanical with a high initial advance. It's surprising what 1 degree either way can do. Hopefully you carb is close..Dyno tuning is a series of tweaks that can create hugh gains in performance if you have alot patience and money for dyno time.
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
The entire purpose of running it on the dyno is to establish and set the best timing curve and to optimize the carb setup. If the dyno guy is not doing that, find another dyno guy - there is no point in running it on the dyno if there is no tuning to optimize it based on the dyno results.
Lars
Lars
Thread Starter
Burning Brakes
Joined: Apr 2013
Posts: 1,072
Likes: 61
From: Saint clair shores Michigan
Yeah thanks guys. I'm gonna have a guy tune it. He's tuned 2 C5Zs for me. But the C3s are a whole different animal. When I was young, I remember every time that I was going to race someone. I'd go under the hood,and advance the timing. Eventually I blew the engine up. I didn't know if it was still safe doing that. But the guy that's gonna do it is a great mechanic. So helhe lead me in the right direction.
Thanks
John
Thanks
John
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Le Mans Master
Joined: Oct 2002
Posts: 7,098
Likes: 378
From: Las Vegas - Just stop perpetuating myths please.
Just 3 degrees change in timing advance can make a significant difference in power output John.
Best dynos are Eddy Current dynos as they can hold a steady rpm while you vary the timing advance and measure the torque/power. But you only do that up to about 4,000rpm. Higher rpm makes a lot more heat and you will notice the engine doesn't feel like it does at lower rpm and most of us won't feel comfortable with the engine held at high rpm. So that's when a "pull" is used to map a WOT run and the dyno records the torque/power/rpm for comparison. Full timing advance should be applied well before 4,000rpm so for WOT your chasing max advance. Before 4,000 you can find the correct advance using rpm "steps".
Don't worry about the torque/power actual numbers as most dyno's you and I can afford are not calibrated or calibrated well enough. Dyno's are just a tool and you use the data to make changes to optimize your power.
Hope this helps more than it confuses.
Best dynos are Eddy Current dynos as they can hold a steady rpm while you vary the timing advance and measure the torque/power. But you only do that up to about 4,000rpm. Higher rpm makes a lot more heat and you will notice the engine doesn't feel like it does at lower rpm and most of us won't feel comfortable with the engine held at high rpm. So that's when a "pull" is used to map a WOT run and the dyno records the torque/power/rpm for comparison. Full timing advance should be applied well before 4,000rpm so for WOT your chasing max advance. Before 4,000 you can find the correct advance using rpm "steps".
Don't worry about the torque/power actual numbers as most dyno's you and I can afford are not calibrated or calibrated well enough. Dyno's are just a tool and you use the data to make changes to optimize your power.
Hope this helps more than it confuses.
