perplexed on timing - Team Camaro Tech
Tech 2000 Our previous General Forum
Replies ONLY - no new topics.

 
LinkBack Thread Tools Display Modes
post #1 of 4 (permalink) Old Feb 6th, 01, 07:36 AM Thread Starter
 
Join Date: Feb 2001
Location: greenville ,s.c.,usa
Posts: 3
Post

could someone explain to me if you have a total advance of say 42 degrees why the spark does not jump to the next cylinder. the distributor has 8 terminals and they are 45 degrees apart.
tony427 is offline  
Sponsored Links
Advertisement
 
post #2 of 4 (permalink) Old Feb 6th, 01, 09:19 AM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,532
Garage
Post

Tony,

Timing degrees are measured at the crank not the distributor. When the advance is set to 0 (zero) deg's the piston is at the top of the cylinder (tdc or top dead center) and about to start down. When it is set at 42deg btdc (before top dead center) the spark fires just before the piston reaches the top.

It takes 360 degrees of the crank to move the piston from tdc down and back up to tdc so the spark fires when the crank has 42 degrees left to complete the full revolution.

I hope that helps...

------------------
...Dennis
The Cars:
'69 RS Convertible w/SS trim
'96 Z28SS #1679 of 2410
The Club:
Camaros Limited Nor-Cal

[This message has been edited by DjD (edited 02-06-2001).]
DjD is offline  
post #3 of 4 (permalink) Old Feb 6th, 01, 09:39 AM
Senior Tech
 
Join Date: Jul 2000
Posts: 170
Post

maybe this will also help.....the rotor is still lined up dead on in the cap with whatever cylinder is about to fire....when you advance the timing it just means that the the cylinder will fire 42 deg. before the piston reaches tdc..as explained earlier, the rotor is still lined up with the terminal for that cyl and not 42 deg's closer to the next terminal....clear as mud, huh?
jblake is offline  
 
post #4 of 4 (permalink) Old Feb 6th, 01, 12:47 PM
Senior Tech
Ray
 
Join Date: Sep 2000
Location: Central FL
Posts: 271
Post

Well, not exactly. This may be true at the initial advance, but not after vacuum or mechanical advance is added in. Actually it will be true at just one point along the advance curve. The vac. and mech. advance (or computer!) actually change the relationship of the rotor and cap at firing.

But it is close enough the rest of the time because like DjD said, distributor degrees are half of crank degrees and 42 is really on 21 degrees at the distributor. Or to look at it another way, each terminal is 90 crankshaft degrees apart.

Some aftermarket distributors let you adjust where the rotor is relative to the terminals separately from the timing adjustment.


------------------
Ray

68 SS Convertible
Corvette(77) Yellow
383 DFI Fuel Injection
on MiniRamII intake,
Trick Flow heads
700R4, 3.31 12bolt Posi
Guildstrand Mod
AGR 12:1 power steering
68SSConvt 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 not 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