300 timing question
Senior User
Joined: Sep 2017
Posts: 194
Likes: 8
From: Union County, NC
Did it also idle high before switching to manifold (full) vacuum for the distributor vacuum advance? I've heard manifold vacuum can increase your idle RPM. Also, if it is idling "high enough", then the mechanical weights could start to kick in as well.
My only other thought is to verify you have no vacuum or gasket leaks around the carb. This could also increase idle speed? If I recall, another symptom of leaks would be that you are unable to "kill" the engine with your idle adjustments - because even with butterflies closed, air is still entering your intake.
I'm by no means a carb guru, and I know nothing about your particular carb (I've only messed with my stock carb).
My only other thought is to verify you have no vacuum or gasket leaks around the carb. This could also increase idle speed? If I recall, another symptom of leaks would be that you are unable to "kill" the engine with your idle adjustments - because even with butterflies closed, air is still entering your intake.
I'm by no means a carb guru, and I know nothing about your particular carb (I've only messed with my stock carb).
Fleet Owner
Joined: Jan 2004
Posts: 26,007
Likes: 575
From: Brentwood,CA
Why would you connect the vacuum advance to manifold vacuum? That causes full advance and if you set the timing like that when under load the vacuum falls off and the timing will severely retard because you didn't have a correct initial baseline.
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Freshman User
Joined: Jan 2018
Posts: 30
Likes: 0
Idle
No leaks that I'm aware of, and yes it idles high on either port, it's a Holley 4brl, I noticed my secondaires were stuck closed the other day so maybe butterfly issue? And the manifold port gave better low end power, but will see how it does mpg wise, and might change backed to timed port after changing my springs in the dist
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Freshman User
Joined: Jan 2018
Posts: 30
Likes: 0
Timing
So i got it running pretty peppy with the 925d springs and 12degrees intial but when i am driving on the freeway and going down a hill, so letting off the gas a bit , it almost has a surge/lurch feeling like it's maybe misfiring a little?
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Try backing off on the vacuum advance one turn at a time. Don't mess with the mechanical or initial timing at this point, just the vac advance.
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