Timing 78 IPC
Thread Starter
Melting Slicks
Joined: Oct 2011
Posts: 2,748
Likes: 90
From: Sacramento California
C2 of Year Finalist (performance mods) 2019
2018 C2 of Year Finalist
Timing 78 IPC
FInished up with the timing light.
Its a 78 L82. Stock except for a performer intake.
12 degrees base.
Mechanical adds 16 degrees.
The Vac can adds 10 degrees.
I believe everything is original/stock. These are the stock specs.
Weights are 106/108
I need more Mechanical advance, I assume the aftermarket weights and springs will allow that?
I have a distributor curve kit, going into it tomorrow.
D
Its a 78 L82. Stock except for a performer intake.
12 degrees base.
Mechanical adds 16 degrees.
The Vac can adds 10 degrees.
I believe everything is original/stock. These are the stock specs.
Weights are 106/108
I need more Mechanical advance, I assume the aftermarket weights and springs will allow that?
I have a distributor curve kit, going into it tomorrow.
D
Last edited by DucatiDon; Nov 3, 2012 at 09:20 PM.
Burning Brakes
Joined: Oct 2001
Posts: 1,241
Likes: 4
From: Okinawa Okinawa
Email Lars and ask him for his latest paper on timing for peak performance. There is a paper in this link http://www.lbfun.com/Corvette/Tech/vettetech.html under "Timing and Vacuum Advance" but I think he has an updated paper. He will respond in 24-48 hrs.
Your answer is yes, different springs will get you what you are looking for. Lars email is below.
V8FastCars@msn.com
Your answer is yes, different springs will get you what you are looking for. Lars email is below.
V8FastCars@msn.com
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,391
From: At my Bar drinking and wrenching in Lafayette Colorado
Don't use aftermarket weights - they're junk. Springs won't change the length of the curve, but select a pair to give you full total timing in the 2500 - 3000 rpm range. Advance your initial timing to produce 34-36 degrees total.
Lars
Lars
Thread Starter
Melting Slicks
Joined: Oct 2011
Posts: 2,748
Likes: 90
From: Sacramento California
C2 of Year Finalist (performance mods) 2019
2018 C2 of Year Finalist
Thanks Lars....I am very familiar with your Timing paper.
I have advanced the initial on the L82 to 19 degrees. This really woke it up.
Im now at 34 with mechanical. I will swap in a gold spring tomorrow and see if I can get it all in by 1500 or so....It has a slight hesitation (getting better) that may just be the mech advance coming in.....between 1200 and 1900 rpm.....
Should I also look for a different vac can that adds more than 10 degrees? 52-34 = 18. Is there an 18 degree HEI vac can? I have not looked yet...
I also have like 17" of vacuum.
Thanks again.
D
I have advanced the initial on the L82 to 19 degrees. This really woke it up.
Im now at 34 with mechanical. I will swap in a gold spring tomorrow and see if I can get it all in by 1500 or so....It has a slight hesitation (getting better) that may just be the mech advance coming in.....between 1200 and 1900 rpm.....
Should I also look for a different vac can that adds more than 10 degrees? 52-34 = 18. Is there an 18 degree HEI vac can? I have not looked yet...
I also have like 17" of vacuum.
Thanks again.
D
Melting Slicks
Joined: Oct 2000
Posts: 2,144
Likes: 195
From: Englewood FL
I saw this older post and wanted to bring it to the top as I would
like to see an answer as I have a very similar car.
The vacuum canister being used in the original post apprears to be
the original one with 10 degrees of vacuum and is the equivalent
of part no. VC 1703.
like to see an answer as I have a very similar car.
The vacuum canister being used in the original post apprears to be
the original one with 10 degrees of vacuum and is the equivalent
of part no. VC 1703.
Advanced
Joined: Oct 2012
Posts: 81
Likes: 6
From: Montgomery Alabama
I recommend the ar15 or ar 23 vac cans. They will both give you around 16 advance. If you have 36 all in with the mech and initial, the 16 gets you to around 52 which is about right. You can order either can at any auto parts store.
