little extra rev
Fleet Owner
Joined: Dec 2009
Posts: 20,678
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From: NorCal
Check your timing and AF mixture. It could be that you're running a tad rich and/or timing is off thus experiencing "run-on" with whatever mixture remains in the cylinder(s) or intake.
Post Fiend
Joined: Apr 2002
Posts: 19,311
Likes: 97
From: Waterloo, Iowa
Ah, the 70s! Wasn't that normal (almost) back then? Sometimes engines would "run on" for quite a while, maybe ten seconds. Form of dieseling iirc. That, and stinky catalytic... rotten eggs. And Disco.
Cranky Old Guy
Joined: Mar 2008
Posts: 3,562
Likes: 6
From: Raphine, Virginia
One more cause could be carbon buildup. The carbon is still burning, igniting the fuel mix even when power is removed. Water drizzled down carb while keeping it running will remove it or slowly pouring Seafoam into carb.
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Senior User
Joined: Dec 2013
Posts: 148
Likes: 0
Will do the seafoam tomorrow...with the vacuum leaks could that explain some of the super low idle I am experiencing when I am braking hard?
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Fleet Owner
Joined: Dec 2009
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From: NorCal
I foresee carburetor adjustments in your future....there is no magic elixir with regards of a properly adjusted carb.
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Senior User
Joined: Dec 2013
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I figured thats what it was...I went about 3000 miles without the carb acting up on me so I consider that a win on my part...will get it back to normal tomorrow...have you put new vacuum lines on before and felt a big difference in the motor or is that just all a mental thing?
Fleet Owner
Joined: Dec 2009
Posts: 20,678
Likes: 82
From: NorCal
I figured thats what it was...I went about 3000 miles without the carb acting up on me so I consider that a win on my part...will get it back to normal tomorrow...have you put new vacuum lines on before and felt a big difference in the motor or is that just all a mental thing?
Replacing all vacuum lines is a good practice. If one goes bad, then the others are likely of the same vintage. I had a co-worker who replaced the radiator every two years. Period. No ifs, ands, or buts. A small crack in a vacuum hose can be tough to trace.. it can be obscured by other components or on the inside curve...all it takes is a pinhole and everything can go awry.
Senior User
Joined: Jan 2013
Posts: 210
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From: New Mexico
I figured thats what it was...I went about 3000 miles without the carb acting up on me so I consider that a win on my part...will get it back to normal tomorrow...have you put new vacuum lines on before and felt a big difference in the motor or is that just all a mental thing?
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
That doesn't answer my question. If the motor originally came with EGR, and the distributor is curved and carburetor jetted for an EGR motor and you're absent the EGR system, you will see these exact same symptoms - all from heightened combustion chamber temperatures. Check the simple stuff first.
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Senior User
Joined: Dec 2013
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Yeah that doesnt answer your question does it...sorry just woke up when I replied wasnt fully firing on all 8...the mechanic that did the rebuild did do a lot of stuff without me knowing and told me to trust him...last time I ever do that without being educated...this is the setup that I have...Im still a little fuzzy on the EGR system so I dont want to say something that is wrong...better to have you look at it