No Timing Advance - WHY!! - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 9 (permalink) Old Apr 10th, 10, 11:03 AM Thread Starter
Senior Tech
Rob
 
Join Date: Apr 2005
Location: Dallas, TX
Posts: 233
No Timing Advance - WHY!!

UGH! My car was purchased from a very non-mechanical woman. It has a chevy SM crate engine, MSD box, coil and distributor. I was setting the timing today and noticed the timing did not advance with RPM. There os no vacuum advance on the distributor. I pulled the cap and saw the weights were "locked out". I think the car was a track car a couple of owners before due to the 1150 CFM carb, HD powerglide and 12-bolt rear. I do not race and have replaced the carb with a 600 cfm and OD tranny. I am sure if I get the mechanical advace back, I will get better performance for weekend cruising.

But - why lock out the advance???
Dynawolf is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old Apr 10th, 10, 11:12 AM
Gold Lifetime Member
Harry
 
dawg's Avatar
 
Join Date: Mar 2004
Location: Colebrook CT.
Posts: 4,030
Re: No Timing Advance - WHY!!

It is common to eliminate both advance mechanisms so that the engine will be at full advance at all times. You will have a few less things that can fail, and setting the timing will be less of a hassle. It is manily these reasons that race cars run \"locked\" timing. as long as it will start ok theres nothing wrong with locking the advance.
Also it enables motors with big upper end cams to gain a bit of off the line torque.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

434 stroker
US Navy retired

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
dawg is offline  
post #3 of 9 (permalink) Old Apr 10th, 10, 11:41 AM
Senior Tech
Ron
 
Join Date: Nov 2006
Location: North Channel Lake Huron
Posts: 3,934
Re: No Timing Advance - WHY!!

Yep a Straight Line WOT Track Star ;o)

If you're on the Street, I suggest you find a Dizzy with a Working Mechanical and Vacuum Advance. Be sure to set an Initial Timing, check the Vacuum at Idle and choose a Canister approx 1.5 to 2 Hg's below it.

Z15CAM - There was a Viper in my Rear View
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

This was my 70 1/2 Z28

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Z15CAM is offline  
 
post #4 of 9 (permalink) Old Apr 10th, 10, 07:29 PM
Gold Lifetime Member
Larry
 
larryh56's Avatar
 
Join Date: Oct 2008
Location: Central Washington
Posts: 1,503
Re: No Timing Advance - WHY!!

Quote:
Originally Posted by Z15CAM View Post
Yep a Straight Line WOT Track Star ;o)

If you're on the Street, I suggest you find a Dizzy with a Working Mechanical and Vacuum Advance. Be sure to set an Initial Timing, check the Vacuum at Idle and choose a Canister approx 1.5 to 2 Hg's below it.
x2 on the street both mechanical AND vacuum advance are necessary for your car to run well.

68 RS Coupe 355/350 TH, Detroit Speed, Hotchkis, Vintage Air, 8.5" 3.42 posi 10-bolt, MagnaFlow 2 1/2" exhaust, etc.

"The public cannot be too curious concerning the characters of public men."
Samuel Adams
larryh56 is offline  
post #5 of 9 (permalink) Old Apr 10th, 10, 10:02 PM
Senior Tech
Steps
 
Join Date: Dec 2005
Location: New Zealand
Posts: 13,316
Re: No Timing Advance - WHY!!

Quote:
choose a Canister approx 1.5 to 2 Hg's below it.
No
The VA will start pulling the intial up as it will be coming in...in practice about 1 to 2 " over still pulls all the way in, As the advance increases so does the idle vac. the general rule of thumb is same as idle.

My Spelling is not incorrect...it is creative

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Steptoe is offline  
post #6 of 9 (permalink) Old Apr 11th, 10, 01:05 AM
Senior Tech
AJ
 
Join Date: Jul 2006
Location: AUSTIN TEXAS
Posts: 3,842
Re: No Timing Advance - WHY!!

I don't see how the race motors can idle at full advance and not gain any... So the centrifugal advance is all in at idle and remains the same?
I know with vacuum added it's pretty common to get around 50+ degrees, but minus the advance, what do these motors idle at, and at say 6,000rpm what is the timing? same as idle? I don't see how the timing couldn't increase thought the speed of combustion is increased with rpm.

The only Mustang I'd ever own is a Fender.

'68 333" Camaro
'14 5.0 Mustang
ace's68 is offline  
post #7 of 9 (permalink) Old Apr 11th, 10, 06:56 AM
Senior Tech
 
Join Date: Mar 2009
Location: TEXAS
Posts: 169
Re: No Timing Advance - WHY!!

Ok, If its locked out with no adavnce, what degree is the timing locked out at? 30,32,34,36,38 etc....?

This can be debated, There are some guys who run locked out dizzy's on the street and some say run vac adv or just mech adv.... The problem with a locked out dizzy is its great for performance but murder on starters.... If this a street car that will see several starts, I would worry about kickback and broken stater noses, and worse even broken blocks around the starter mount..... Locked out timming is not great for a car thst is like a daily driver, or you drive often IMO......

But you have to be careful how you interpret information from these forums... If this is a daily driver, you want to talk to guys that daily drive their cars, but too often guys try to cross daily driving and race practices and it is just breeds potential unhappiness........ Guys will say "I did this too my car and it runs fine" Then you ask them, how often do you drive it, and they say 500-1000 miles a year if that.... Weekend warriors or Seasonal warriors........... I like to talk to the guys that drive their cars 5+ days a week......

Stay as close to OEM as possible..... I have seen more OEM with a few mods last longer than, Fully moded forged etc....
shonuff is offline  
post #8 of 9 (permalink) Old Apr 11th, 10, 07:07 AM
Senior Tech
Patrick
 
Join Date: Jun 2005
Location: Quitman Georgia
Posts: 2,519
Re: No Timing Advance - WHY!!

If the car had a 1150cfm carb on it I think going to a 600cfm may be too small for it. Give us some engine specs.

69RS/SS,383,10:1cr,4.10,60ft1.6sec,1/[email protected],1/[email protected],Vicjr,RPMheads,750dp, Proform main body, cam,246*-250*@.050,.510,522,1.6rr,700r4,3200stall
383 IS SOLD!
Building a 489BBC

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
speedfreek is offline  
post #9 of 9 (permalink) Old Apr 11th, 10, 08:08 AM
Gold Lifetime Member
Tom
 
Join Date: Mar 2008
Location: the 02176
Posts: 5,985
Re: No Timing Advance - WHY!!

Quote:
Originally Posted by ace's68 View Post
I don't see how the race motors can idle at full advance and not gain any... So the centrifugal advance is all in at idle and remains the same?
I know with vacuum added it's pretty common to get around 50+ degrees, but minus the advance, what do these motors idle at, and at say 6,000rpm what is the timing? same as idle? I don't see how the timing couldn't increase thought the speed of combustion is increased with rpm.
Let's say you are locked at 36 degrees. Race motors spend little if any time on the lower part of the centrifugal curve anyway. If your curve has your full mechanical advance in at say 2,800 and you launch your drag car higher than that anyway, no need for mechanical curve. (Timing would be the same 36 at 6k rpms)

Likewise if you have a mild engine, stock curve, 16 initial, 18 vac, and a couple mechanical pulled in at idle, you may have 36 at idle. So it's just about the same thing as the drag car at idle.

The 50+ you suggest is a combination of initial, high vac so the can is all in(cruise condition), and an RPM high enough so that the mechanical is all in/very high. Say, part throttle highway cruising at 3,500 rpms.

'67 rs - ordered new by my Grandfather
327 L30, K-K, Deluxe int, tach & gauges, 12 bolt posi, 4 speed.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
-
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Melrose RS is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Team Camaro Tech forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address.
NOTE we receive a lot of registrations with bad email addresses. IF you do not receive your confirmation email you will not be able to post. contact support and we will try and help.
Be sure you enter a valid email address and check your spam folder as well.



Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome