Notices
Corvette C1 & Corvette C2 1953 through 1967

MSD timing vs idle issue

  #1  
Old 05-26-2007, 11:08 AM
73shark's Avatar
Super Moderator
Thread Starter
Join Date: Apr 2006
Location: KC, MO area
Posts: 2,734
Default MSD timing vs idle issue

Helping a friend with a 427/425 that we put a MSD dist and spark box in. The problem is according to the MSD graph, the mech. advance starts at 0 rpm and is about 4 degrees at 1,000rpm. So when setting the timing at 850, there's apparently already a little mech. advance in.OK now when you blip the throttle, you get more mech. advance which in turn wants to cause the engine speed to increase which won't let the mech. go back to where it was. Therefore the idle is now up around 1100 and will slowly (~30-40 seconds) come back to 850. All of the MSD springs show this same amount of advance at 1,000 rpm. Any ideas??? [sm=dontgetit.gif]
 
  #2  
Old 06-03-2007, 09:11 PM
Join Date: Apr 2007
Location:
Posts: 16
Default RE: MSD timing vs idle issue

Iwould try putting stiffer springs or lighter weights in. If you cant get it right, try bringing it to a speed shop with a distributor machine, they will be able to set it up so it comes in exactly where it should

-Rich
 
  #3  
Old 06-04-2007, 12:14 PM
73shark's Avatar
Super Moderator
Thread Starter
Join Date: Apr 2006
Location: KC, MO area
Posts: 2,734
Default RE: MSD timing vs idle issue

Tried that but all of the MSD spring graphs show mech advance starting a zerorpm and reaching about 4 degrees at 1,000 rpm. Since with the cam we've got, we are idling at about 900 rpm, can't see how once the engine goes above idle, it will ever return since the advance has kicked in.

While it will slowly (~20 seconds) return to the idle setting when in the driveway, when we take it out and drive it, it wants to idle at about 1,100 rpm.
 
  #4  
Old 07-18-2007, 08:41 PM
Join Date: Apr 2007
Location:
Posts: 16
Default RE: MSD timing vs idle issue

what about the weights? could you possibly put a lighter weight on or grind down the weights that came with it?

-Rich
 
  #5  
Old 07-18-2007, 10:28 PM
pg's Avatar
pg
pg is offline
Senior Member
Join Date: Aug 2006
Location: NC
Posts: 1,152
Default RE: MSD timing vs idle issue

Hi 73shark, if your using a Rochester carb, is the power valve working properly or hanging up? PG
 
  #6  
Old 07-20-2007, 10:35 PM
73shark's Avatar
Super Moderator
Thread Starter
Join Date: Apr 2006
Location: KC, MO area
Posts: 2,734
Default RE: MSD timing vs idle issue

Running an original Holley. We finally bit the bullet and put a stronger spring in so the advance doesn't start at idle and all's well now. Finally convinced him that on the last dyno run a couple of years ago, it didn't appear that the secondaries were fully opening. Put the next lighter spring in and it goes like the proverbial raped ape now.

Thanks for the tips.
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
diojr
Corvette C4 Forum
3
08-06-2007 03:39 PM
73shark
Corvette C3 Forum
1
05-26-2007 12:21 PM
vetterz06
Corvette C3 Forum
1
08-26-2006 03:33 AM
hangn7
Corvette C4 Forum
1
05-15-2006 09:30 AM
hangn7
General Tech
0
05-15-2006 09:30 AM


Thread Tools
Search this Thread
Quick Reply: MSD timing vs idle issue


Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.