Why is total advance so high ? - Team Camaro Tech
Engine General Engine Discussion.

 
LinkBack Thread Tools Display Modes
post #1 of 15 (permalink) Old Mar 11th, 03, 08:13 AM Thread Starter
 
Join Date: Oct 2002
Location: Hansville,Wa. USA
Posts: 11
Question

My initial advance is set to 15 deg. with the vacuum adv. disconnected and the carb. port blocked off. At 3000 rpm the advance is 46 deg. Does this seem too high? If I try to bring the initial advance down any lower the engine knocks, or if I drop the idle rpm down much below 800 I get a knock. It seems that total advance should be in the mid 30s with an initial of around 10 or below. Am I off base here?
MSD pro dist., AFR 195 heads 72 cc, 10:1 comp., Ext. Energy 268, Dommed forged TRW pistons. 170 psi.
tdsk1967 is offline  
Sponsored Links
Advertisement
 
post #2 of 15 (permalink) Old Mar 11th, 03, 08:39 AM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,484
Garage
Post

I can't even begin to take a guess as to why your mill knocks when you reduce the timing or lower the idle. When you say knock are you refering to run-on or detonation (pinging) or? Can you go into more detail, rpm this happens at, when under a load or when shutting it off?

As for your distributor it has 31 degs mechanical built into it (46 total minus 15 initial). Sounds like it's been played with and needs to be played with some more and limited to about 20 degs of mechanical movement.

...Dennis

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


"Don't take life so serious, you won't get out alive..."
DjD is offline  
post #3 of 15 (permalink) Old Mar 11th, 03, 09:15 AM Thread Starter
 
Join Date: Oct 2002
Location: Hansville,Wa. USA
Posts: 11
Post

It knocks when the rpm drops below 700,either because I have tried to retard the initial advance below 15 or because I drop the curb idle below 700. This is under a no load condition. How do I change the built in advance of the dist. The dist. is brand new. Ther is no detonation when I turn the ignition off.
tdsk1967 is offline  
 
post #4 of 15 (permalink) Old Mar 11th, 03, 09:24 AM
 
Join Date: Oct 2002
Posts: 2,045
Angry

I am imagining that your statement of 170psi is that of the engines cylinder pressure.

You are getting to the ragged edge of being able to run pump without detonation (a 170psi with poor timing control is a bad thing). I would say it is paramount to get the timing issues resolved. I agree with Dennis, it sounds like the mechanical advance springs might be the first place you should screwtinize. Pop the cap and rotor and use the MSD supplied chart for configuring the springs, for the amount of and rate of advance.

But 15-16 initial is right about where you want to be.....
chicane67 is offline  
post #5 of 15 (permalink) Old Mar 11th, 03, 09:34 AM Thread Starter
 
Join Date: Oct 2002
Location: Hansville,Wa. USA
Posts: 11
Post

I'll look at the chart your speaking of. and get the timeing problem fixed first. I;m running 91 oct. now. Do you think I should add some octane booster to that?
tdsk1967 is offline  
post #6 of 15 (permalink) Old Mar 11th, 03, 09:45 AM
 
Join Date: Oct 2002
Posts: 2,045
Post

If you get the timing dialed in, you should be OK.....but precise timing control is going to be the key in your engines longevity. I see that you stated an MSD distributor, this is a good thing, as they are pretty soild in maintaining accurate timing.

You wont really know if you will require an additive or not until you get the timing rock solid. Maybe.....maybe not..... tough to say without 'seeing' the total package.

But I will say that 180-185 is the upper limit on 91 pump gas and that is with using MSD's Digital 7 Programmable......My last power plant was a small block making 600+ish HP on 91 pump and the only wat I got it to live was with the Digital 7 Pro. on 91 R/M octane without additives.
chicane67 is offline  
post #7 of 15 (permalink) Old Mar 11th, 03, 11:37 AM
Gold Lifetime Member
Steve
 
Join Date: May 2001
Location: Clermont, FL
Posts: 296
Post

Have you checked to see that the proper advance stop bushing is in place. MSD gives you several bushing thicknesses to control the total amount of advance. Sounds like your bushing may be missing.
ccpeat is offline  
post #8 of 15 (permalink) Old Mar 11th, 03, 04:15 PM
Moderator
David Pozzi
 
davidpozzi's Avatar
 
Join Date: Nov 1999
Location: Central California, USA
Posts: 10,094
Post

Some timing lights won't work right with an MSD.
I think the dial back type are worse in some cases.

I like a plain timing light with timing tape or degeed balancer.
David

Here is a quote from the MSD website:


Timing Fluctuations
<http://www.msdignition.com/images/5pixspa.gif> If your timing seems to be jumping all over the place, check the following items:

* What kind of timing light are you using? Many lights have trouble reading the MSD's capacitive discharge multiple sparks. Dial back timing lights are not recommended. Try another non-adjustable light and check the timing again. MSD offers a Timing Light, PN 8990.
* Make sure you are not using Solid Core wires.
* Inspect the routing of the Magnetic Pickup Harness. It should be routed clear of the coil primary wires and plug wires. It is best to route it along a ground plain such as the firewall, frame or engine block to form a shield around it.
* Check the polarity of the magnetic pickup wires of the distributor. Reverse the connectors and check the timing again. The correct polarity is whichever connection gives the most retarded timing.
* On Chevrolet engines, if the timing is retarding 10 - 20 degrees inspect for cam-walk. This is especially prevalent on engines with a chrome or stock timing chain cover that is actually bowing forward allowing the cam to "walk".

Check my web page for First Gen Camaro suspension info:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

67 RS 327 original owner. 1965 Lola T-70
davidpozzi is offline  
post #9 of 15 (permalink) Old Mar 11th, 03, 05:11 PM
DjD
Retired
Dennis
 
DjD's Avatar
 
Join Date: Apr 1999
Location: Fortuna, CA
Posts: 26,484
Garage
Post

Good call Dave!! It's come up many times in the past... [img]graemlins/clonk.gif[/img]
DjD is offline  
post #10 of 15 (permalink) Old Mar 11th, 03, 05:51 PM
 
Join Date: Oct 2002
Posts: 2,045
Post

Go Dave.....Go Dave.....Go Dave......
chicane67 is offline  
post #11 of 15 (permalink) Old Mar 11th, 03, 05:59 PM
Senior Tech
Nick
 
Join Date: Nov 2001
Location: BARRIE ONT CANADA
Posts: 755
Post

Make sure your H/B didn't spin.When the keeper is at 12 oclock. 0 is at 11.Or check it with #1 cylinder.Mr. Nick
MRCOOL_RSSS350 is offline  
post #12 of 15 (permalink) Old Mar 11th, 03, 07:25 PM Thread Starter
 
Join Date: Oct 2002
Location: Hansville,Wa. USA
Posts: 11
Post

Thanks for all the advice:
I did have some arcing on my plug wires to the MSD primary coil wires. After I cleared that problem up I was able to get a good timeing base line set up. I;m using a Craftsman timeing light with a variable timeing dial. At 3000 rpm now I get 38 deg. of advance at 3000 rpm.
tdsk1967 is offline  
post #13 of 15 (permalink) Old Mar 11th, 03, 07:40 PM Thread Starter
 
Join Date: Oct 2002
Location: Hansville,Wa. USA
Posts: 11
Post

I'm kind of new to "The Team Camaro" site but I appreciate the responces I got for my questions about my timeing problems.
tdsk1967 is offline  
post #14 of 15 (permalink) Old Mar 11th, 03, 08:46 PM
Moderator
David Pozzi
 
davidpozzi's Avatar
 
Join Date: Nov 1999
Location: Central California, USA
Posts: 10,094
Post

I've heard it here enough times, plus seen it myself with a friend setting timing with a dial back light, - couldn't do it.

Make sure the plug wires are the spiral core type when using an MSD unit.
David

Check my web page for First Gen Camaro suspension info:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

67 RS 327 original owner. 1965 Lola T-70
davidpozzi is offline  
post #15 of 15 (permalink) Old Mar 13th, 03, 09:38 PM
Senior Tech
Lonnie
 
Join Date: Mar 2000
Location: Mesa, AZ
Posts: 744
Post

Don't the multiple sparks go away above 3000 rpm? Shouldn't a dial back work fine checking total timing at say 3500 rpm?

67 Camaro [email protected], [email protected], 1.455 60ft 421sbc
Lonnie67 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