![]() |
Register or Log In To remove these advertisements. |
|
|
![]() |
|
Thread Tools | Display Modes |
|
![]() |
#1 |
Registered User
Join Date: Sep 2010
Location: Sevierville, TN
Posts: 6
|
Timing 12 initial 22 total?
Hey guys, my first post!
I picked up a 70 c-30 about a month ago and have been trying to get her running right since.( it broke down halfway home, flooded out) Its a 283 out of a 65 c-10, with a 68 buick lesabre quadrajet on top. Atleast thats what my research shows. Im assuming motor is fairly stock built. I rebuilt the carb and now shes running ok, but i figured i'd give her a tuneup before i go break down again. I'm trying to set the timing but thats where im running into problems. I set her to 12* intial, dizzy vac unplugged. I reved it where the timing stopped advancing and got 22*. (no tach to go by) Shouldnt it be around 34-36? With the dizzy vac hooked back up i got around 41* before it stopped advanceing. Its a points ignition, and i just figured out how to use a timing light 2 days ago. Any help would be appreciated guys. |
![]() |
![]() |
![]() |
#2 |
Registered User
Join Date: Aug 2010
Location: Harrison Arkansas
Posts: 164
|
Re: Timing 12 initial 22 total?
You're right total mechanical advance should typically be 34 to 40 degrees. Compression and cylinder head chamber design being big variables in total timing. Camshaft duration has a big effect on the curve and initial timing.
Old iron factory heads often use about 4 more degrees of total timing than modern heads. I found Vortecs to be very sensitive to total too much timing. Sort of a by product of their efficient chambers. Don't try to use the vacuum advance as a band aid. It will look right using a timing light but under load you won't be making the vacuum you do while you're reving and setting the timing. Kerry P |
![]() |
![]() |
![]() |
#3 |
Registered User
Join Date: Sep 2010
Location: Sevierville, TN
Posts: 6
|
Re: Timing 12 initial 22 total?
Thanks for the tips
When i first checked the timing it was advance around 20 or so, it was up there. I googled some more and im thinking its spring loaded arms on top under the cap. I guess thats why they had it timed so high, to compensate for the bad dizzy. |
![]() |
![]() |
![]() |
#4 |
Registered User
![]() Join Date: Jul 2006
Location: Ozark, MO
Posts: 4,887
|
Re: Timing 12 initial 22 total?
replace the bushings and springs, that usually helps and you can also get adjustable vacuum advance canisters for a few bucks.
__________________
'20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids
|
![]() |
![]() |
![]() |
#5 |
Registered User
Join Date: Aug 2010
Location: Harrison Arkansas
Posts: 164
|
Re: Timing 12 initial 22 total?
Mechanical advances get dirty, get rusty and/or wear and then stick or become erratic.
It's a good idea to take a look under the cap. Sometime cleaning and lubricating fix the issue. Kerry P |
![]() |
![]() |
![]() |
#6 |
Registered User
Join Date: Sep 2010
Location: Sevierville, TN
Posts: 6
|
Re: Timing 12 initial 22 total?
The arms looked pretty corroded. This distributor is gonna need some work put into it and i dont really spend any money on the points system thats on it now.
I've got another SB chevy thats got a HEI on it, im gonna just throw it on the truck for now to get it running and worry about a dizzy for the other chevy later. Thanks for the replys guys, i appreciate the help. |
![]() |
![]() |
![]() |
#7 | |
Registered User
Join Date: Aug 2010
Location: Harrison Arkansas
Posts: 164
|
Re: Timing 12 initial 22 total?
Quote:
Just something to watch for: Typically an HEI works with full voltage and the coil on a pre=HEI vehicle is fed with reduced voltage via a "resistance wire". Kerry P |
|
![]() |
![]() |
![]() |
Bookmarks |
Thread Tools | |
Display Modes | |
|
|