timing advanced!! is it needed - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 04-25-2013, 04:16 PM
Registered User
 
Join Date: May 2010
Location: pownal, vt
Posts: 44
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
timing advanced!! is it needed

seems like a dumb question but let me explain myself!!!

I have a 400 sbc that will be running E85 and a vortech supercharger at 6-8 psi. Right now I have a vacuum advanced distrib. which does me no good because I wont make much vacuum if any.

Do i really need to have timing advanced or can i just cap the port and have it advanced all the time? I can buy a mechanical timing advanced but i have never delt with that, what should I set it to open at?

Thanks for you input
-Dana

    Advertisement
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 04-25-2013, 06:14 PM
Registered User
 
Last photo:
Join Date: Apr 2007
Location: Seattle, Wa
Posts: 6,822
Wiki Edits: 0

Thanks: 4
Thanked 449 Times in 384 Posts
Quote:
Originally Posted by djohnson308 View Post
seems like a dumb question but let me explain myself!!!

I have a 400 sbc that will be running E85 and a vortech supercharger at 6-8 psi. Right now I have a vacuum advanced distrib. which does me no good because I wont make much vacuum if any.

Do i really need to have timing advanced or can i just cap the port and have it advanced all the time? I can buy a mechanical timing advanced but i have never delt with that, what should I set it to open at?

Thanks for you input
-Dana
Typically the vacuum advance on a blower motor works like usual in areas where the blower isn't boosting manifold pressure. For a street engine operating under conventional vacuum conditions will be the most common condition. Therefore, the overall timing is pretty normal. But you can't have the advance all the way in all the time because as the blower pumps up the manifold pressure over atmospheric the burn speed in the cylinders also increases so a means of ignition retard is needed. So that pressure is used against a "vacuum" style advance mechanism to reduce the total advance because as the pressure and burn speed increases in the cylinders without some sort of pressure retard on the advance the engine will go into detonation. And with a blower; that's detonation on steroids!

Bogie
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 04-25-2013, 07:24 PM
33Willys77's Avatar
Registered User
 
Join Date: Jan 2013
Location: Wisconsin
Posts: 406
Wiki Edits: 0

Thanks: 7
Thanked 57 Times in 55 Posts
It is very important to know your advance curve before you run the motor. Blower motors like/need all the intial advance they can get. Be very conservative on the timing if you are not going to have a boost retard.
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 04-25-2013, 07:35 PM
Registered User
 
Join Date: May 2010
Location: pownal, vt
Posts: 44
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
oh man, looks like I have opened Pandoras box. The supercharger world is very new to me.

so I need to look into retarding my timing... mind blown haha, are there distributors that retard?
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 04-25-2013, 08:02 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 9,086
Wiki Edits: 0

Thanks: 17
Thanked 333 Times in 313 Posts
You can get a boost retard. You still need vacuum and mechanical advance though. Why don't you think you'll have vacuum? Are you using a carb or Efi?
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 04-25-2013, 09:01 PM
68NovaSS's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Working with chromed bolts
Last journal entry: New to me T-Bucket
Last photo:
Join Date: Sep 2002
Location: Nine Mile Falls/Suncrest, WA
Posts: 5,249
Wiki Edits: 9

Thanks: 105
Thanked 133 Times in 124 Posts
I do not use vacuum advance on my carbed 8-71 small block pro street car, and use an MSD BTM along with an AIS injection system.
__________________
Boost adds dignity to what would otherwise be a vulgar brawl...

Midnight Sun Street Rod Association
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 04-25-2013, 09:02 PM
33Willys77's Avatar
Registered User
 
Join Date: Jan 2013
Location: Wisconsin
Posts: 406
Wiki Edits: 0

Thanks: 7
Thanked 57 Times in 55 Posts
What are your engine specs (cam, compression, etc.). You may not need to have any advance mechanism (vacuum or mechanical). With the correct stuff, you can just lock out the distributor. If there is enough overlap, there is enough bleed off and the motor will not kick back. If it does, you can simply run a separate ignition toggle (spin the motor over then click it on) or get a start retard. There will probably be some others on here that will give you more advice for the SBC.
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 04-26-2013, 06:41 AM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 9,086
Wiki Edits: 0

Thanks: 17
Thanked 333 Times in 313 Posts
Quote:
Originally Posted by ap72 View Post
You can get a boost retard. You still need vacuum and mechanical advance though. Why don't you think you'll have vacuum? Are you using a carb or Efi?
After the last few posts, I feel I should clarify this.

You may not NEED ignition advance, however it SHOULD have a mechanical if you do not have steep gears and a loose stall, and if you drive on the street with it at part throttle then you SHOULD have vacuum advance.

Those two items may not show up as making a difference on a WOT dyno sweep, BUT they will lead to less fuel consumption, a cooler running engine, and much increased durability.
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 04-26-2013, 09:50 AM
spinn's Avatar
Bubbles is the girl next door
 

Last journal entry: This makes a huge difference
Last photo:
Join Date: Oct 2004
Location: Midnight
Posts: 2,498
Wiki Edits: 0

Thanks: 13
Thanked 82 Times in 80 Posts
Right.

The mechanical curve sets the flame front to advance across the chamber. At low rpm it does not need to lite as far ahead of the piston coming around.

You can lock it out at 36 and drive it , in most NA cases without harm. Sometimes you can create a condition on a lean burning system where 36 will detonate. Beware. You will also need a retard/interupt for hot start if you lock it. Always run vacuum advance driving round. FI apps do not use manifold vacuum for the vacuum pod. Sometimes the emissions will clean up a little with the ported vacuum advance operating in limited capacity.

For a supercharged combination you need something to retard the timing, as rpm increases. Boogie informed you.
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 04-26-2013, 07:25 PM
33Willys77's Avatar
Registered User
 
Join Date: Jan 2013
Location: Wisconsin
Posts: 406
Wiki Edits: 0

Thanks: 7
Thanked 57 Times in 55 Posts
Quote from Spinn: For a supercharged combination you need something to retard the timing, as rpm increases.


You should have something to retard the timing as the BOOST is increased, not RPM.

I have my timing locked @ 33 degrees - works very well and plugs read great (safe a little on the rich side at WOT). I run a 6BTM, have just installed water/meth injection, and no need for a start retard / ingintion interrupt switch. (FYI - I have a Hemi so I dont need a lot of advance) I am hoping with the water/meth, I may not need the timing retard under boost.
Reply With Quote Quick reply to this message
The Following User Says Thank You to 33Willys77 For This Useful Post:
BlueOvalTreasure (04-28-2013)
  #11 (permalink)  
Old 04-27-2013, 08:22 AM
spinn's Avatar
Bubbles is the girl next door
 

Last journal entry: This makes a huge difference
Last photo:
Join Date: Oct 2004
Location: Midnight
Posts: 2,498
Wiki Edits: 0

Thanks: 13
Thanked 82 Times in 80 Posts
Nah, unfortunately for you, superchargers are rpm dependent. So as the rpms rise.

No points awarded for correction.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 04-27-2013, 09:01 AM
spinn's Avatar
Bubbles is the girl next door
 

Last journal entry: This makes a huge difference
Last photo:
Join Date: Oct 2004
Location: Midnight
Posts: 2,498
Wiki Edits: 0

Thanks: 13
Thanked 82 Times in 80 Posts
To explain from my point of view... Is as if you are driving and getting on it.

Your point of view would be the scientific explaination of the mechanics of it.

For some reason, I felt that I needed to shed some light on this.
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 04-27-2013, 02:34 PM
33Willys77's Avatar
Registered User
 
Join Date: Jan 2013
Location: Wisconsin
Posts: 406
Wiki Edits: 0

Thanks: 7
Thanked 57 Times in 55 Posts
A blower will only make boost when its under a load. You could rev the engine up and past 10K and it would not create boost, unless it is under a load - and even if it was a light load on the engine, you may not reach full boost. Therefore, timing retard should be done with a BOOST retard, not a RPM retard. You only need to retard the timing under boost situations.
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 04-27-2013, 06:37 PM
spinn's Avatar
Bubbles is the girl next door
 

Last journal entry: This makes a huge difference
Last photo:
Join Date: Oct 2004
Location: Midnight
Posts: 2,498
Wiki Edits: 0

Thanks: 13
Thanked 82 Times in 80 Posts
I think there is a misunderstanding.

My comment was, For a supercharged combination you need(want really) something to retard the timing, as rpm increases.

For instance,

I stepped on the gas pedal on my supercharged engine. There was nothing in place to retard the timing. As rpm increases it still continues to knock and rattle. I should get that MSD btm to cure the condition. It would be nice to have...

Not claiming anything technical.

For some reason you said that you corrected my post.

There was nothing wrong in my post.

You should have just added your boost comment if you thought it needed to be added. Not try to tell me WHAT I MEANT in my own post.
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 04-27-2013, 06:49 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 29
Posts: 9,086
Wiki Edits: 0

Thanks: 17
Thanked 333 Times in 313 Posts
Spinn, he's trying to politely tell you're wrong. And you are. Boost retard is boost dependent not rpm and boost is not rpm dependent but depends on the throttle opening (after spool up of course).

Your understanding of timing is over simplified.
Reply With Quote Quick reply to this message

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
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 for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

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


Similar Threads
Thread Thread Starter Forum Replies Last Post
Advanced Timing Question for built 4.3 S10BlazerBuilt Engine 19 10-21-2012 06:25 PM
Advanced timing 454 turchiac Engine 15 05-15-2012 03:01 PM
New motor wont run unless the timing is way advanced z-adamson Engine 18 03-30-2012 04:12 PM
SBF - Wont run unless timing WAY advanced?? z-adamson Engine 9 01-02-2011 01:11 PM
40 degrees advanced timing to run kleen56 Engine 10 11-08-2010 09:35 PM


All times are GMT -6. The time now is 12:20 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.