MSD HEI removed vacuum canister?
Thread Starter
Race Director
Joined: Aug 2000
Posts: 10,854
Likes: 3
From: HONOLULU HAWAII
MSD HEI removed vacuum canister?
I was advised by Pro-Gas people to remove my vacuum advance canister and run Mechanical Advance.....Will this hurt my quarter mile times?....How will this affect my performance or street driving?.....I'm running the MSD P/N 8365 distributor.....is this a good system?....are there better systems out there? :seeya
Burning Brakes
Joined: Feb 2001
Posts: 866
Likes: 1
From: Peabody,MA,USA
Re: MSD HEI removed vacuum canister? (8T1-7T9 BIONIC VETTE)
I don't run a vacuum advance either. The vacuum advance will give you better gas mileage . My car doesn't get gas mileage and I can't tell any difference whan I have the vacumm advance hooked up. Your ignition is a really good ignition. It is not the best ignition in the World but it is close enough.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: MSD HEI removed vacuum canister? (8T1-7T9 BIONIC VETTE)
Anybody that told you to remove it doesn't understand ignitions. At wide open throttle like 1/4 drag racing your not creating enough vacuum to even bring in any advance. So your 1/4 mile time will not change.
You do have the top of the line MSD dist. My next move will be to distributorless ign. The whole idea of rotor and cap is old and they degrade from the first time you fire them up.
You do have the top of the line MSD dist. My next move will be to distributorless ign. The whole idea of rotor and cap is old and they degrade from the first time you fire them up.
Race Director
Joined: Jun 2000
Posts: 10,036
Likes: 667
From: FL
Re: MSD HEI removed vacuum canister? (gkull)
Vaccuum works at part throttle. Like said above, eliminating it will not affect 1/4 performance. But just cruising is where it pays off. I can pull 18-20 mpg on the highway without overdrive.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,444
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Re: MSD HEI removed vacuum canister? (8T1-7T9 BIONIC VETTE)
I was a little harsh on saying that they don't know ignitions 
In a pure none street car. trailer to the track drag machine you do not want vac. adv. IT makes for a untuneable carb and timing nightmare. Because jetting, idle speed all bump up with the addtional advance smoothing the initial. Being hooked to the ported carb port your not supposed see any additional. But you do with a quick hit on the throttle.
So yes, they do have a point. For a street car. You do the jets and squirters with it disconnected and make it run the best you can with carb and timing. then hook up your vac advance.
In a pure none street car. trailer to the track drag machine you do not want vac. adv. IT makes for a untuneable carb and timing nightmare. Because jetting, idle speed all bump up with the addtional advance smoothing the initial. Being hooked to the ported carb port your not supposed see any additional. But you do with a quick hit on the throttle.So yes, they do have a point. For a street car. You do the jets and squirters with it disconnected and make it run the best you can with carb and timing. then hook up your vac advance.
