HEI Distributor problem
Melting Slicks
Joined: Apr 2009
Posts: 2,632
Likes: 112
From: Great Plains Iowa
How are you determining you're only getting 8 degrees of mechanical? HEI's have 20-25 degrees of mechanical advance so if yours is only getting 8 degrees something is preventing the weights from moving all the way. With the cap off grab the rotor and twist it fully in both directions. The rotor should pivot at least 20 degrees.
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 9,429
Likes: 44
From: Macon, GA
How are you determining you're only getting 8 degrees of mechanical? HEI's have 20-25 degrees of mechanical advance so if yours is only getting 8 degrees something is preventing the weights from moving all the way. With the cap off grab the rotor and twist it fully in both directions. The rotor should pivot at least 20 degrees.
Weights are free and I've changed springs. I can fully open weights by hand and still move advance mechanism a good amount. I'll try to post a video.
Melting Slicks
Joined: Jan 2004
Posts: 3,245
Likes: 210
From: Detroit MI
sperkins, help me out here. Why is the vacuum advance can facing the wrong direction? Is that a Pontiac HEI distributor? Don't Pontiac engines run the distributor the opposite direction compared to Chevy's??
Last edited by 69autoXr; Jul 15, 2015 at 08:58 AM.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
10 Things C8 Corvette Owners Hate (But Won't Tell You)
Joe Kucinski
10 Best Corvettes Coming to Barrett-Jackson Palm Beach 2026!
Brett Foote
Every Corvette Grand Sport Explained! (C2, C4, C6, C7, & C8)
Joe Kucinski
Grand Sport & Grand Sport X Launch Alongside All-New 535hp LS6 V8!
Michael S. Palmer
5 Reasons Bad Drivers Crash & 5 Ways to Avoid a Costly Mistake!
Joe Kucinski
7 Bolt-On Upgrades From Extreme Online Store to Level Up Your C6 Corvette
Pouria Savadkouei
Melting Slicks
Joined: Nov 2010
Posts: 2,216
Likes: 112
From: Michigan
Melting Slicks
Joined: Dec 2009
Posts: 3,195
Likes: 632
From: Thunder Bay
There's something weird about that distributor. The vacuum advance can is pointing the wrong way, and it looks like the advance weights are operating on the wrong side of the eccentric on the shaft. I would need to compare the setup to a known good distributor. It looks like there is problem with the geometry of the weights and the shaft.
Thread Starter
Le Mans Master
Joined: Oct 2005
Posts: 9,429
Likes: 44
From: Macon, GA
You guys are sharp. I was wondering if anyone would notice that it's not a Chevy distributor.
It's actually an Oldsmobile and yes, like the Pontiac it does spin counterclockwise. I tinkered with it a little tonight, ground down the weights and got the mechanical advance up to 14 degrees. The initial is set to 22 and total at 36. Not the best, but it's 100% better.
It's actually an Oldsmobile and yes, like the Pontiac it does spin counterclockwise. I tinkered with it a little tonight, ground down the weights and got the mechanical advance up to 14 degrees. The initial is set to 22 and total at 36. Not the best, but it's 100% better.
Melting Slicks
Joined: Jan 2004
Posts: 3,245
Likes: 210
From: Detroit MI
I was doing a little 'net research today about Pontiac and Olds HEI distributors. Apparently they mount the advance weights and center plate flipped upside-down relative to Chevy's, which agrees with what drwet was saying. I wonder if that is limiting the centrifugal advance in your case?
I would have expected with the reverse-direction distributor that the centrifugal advance mechanism would also operate in the opposite direction of a Chevy centrifugal advance. I'm not sure what I'm missing in that thought process.
My HEI is also around 20 initial to get to 36 total. I'm sure I'm getting some centrifugal advance at idle with the light springs I have. I'll get around to improving this some day, but for what I use my car, it's fine for now.
I would have expected with the reverse-direction distributor that the centrifugal advance mechanism would also operate in the opposite direction of a Chevy centrifugal advance. I'm not sure what I'm missing in that thought process.
My HEI is also around 20 initial to get to 36 total. I'm sure I'm getting some centrifugal advance at idle with the light springs I have. I'll get around to improving this some day, but for what I use my car, it's fine for now.
Last edited by 69autoXr; Jul 15, 2015 at 11:43 PM.
