SoCal Jet Boats

Discussion => The No Wake Zone => Topic started by: eliminator18 on March 15, 2012, 07:15:27 AM

Title: Vaccume advance?
Post by: eliminator18 on March 15, 2012, 07:15:27 AM
How many of you guys use the Vaccume advance on your distributor to carb? My engine is capable of doing so, but the privious owner capped them off? Would I see any difference with it hooked up, or should I leave it alone?
Title: Re: Vaccume advance?
Post by: berkbryan on March 15, 2012, 07:34:32 AM
I dont use it but my dist. does not have it
Title: Re: Vaccume advance?
Post by: GT Jets on March 15, 2012, 07:53:36 AM
How many of you guys use the Vaccume advance on your distributor to carb? My engine is capable of doing so, but the privious owner capped them off? Would I see any difference with it hooked up, or should I leave it alone?

IMHO it will hurt performance...

I don't really even know why they call it a vacuum "advance"...A marine engine, especially a jet makes almost no vacuum at all at wide open throttle or even when at a 3500 RPM cruise. The way a vacuum advance works on a car is when the vehicle is cruising down the freeway the engine has a fairly high vacuum signal, this signal then advances the timing improving fuel economy and generating a small amount more HP, once the throttle is increased the vacuum signal drops and retards the timing a small amount to prevent detonation.

Leave it disconnected or better yet find an eliminator kit and set the timing for high RPM, not low...

GT
Title: Re: Vaccume advance?
Post by: mash on it on March 15, 2012, 08:00:29 AM
If its GM HEI, get a vacuum adv lockout plate
http://www.speedwaymotors.com/Vacuum-Advance-Lock-Plate,7317.html (http://www.speedwaymotors.com/Vacuum-Advance-Lock-Plate,7317.html)

and a recurve kit
http://www.speedwaymotors.com/HEI-Advance-Curve-Kit,740.html (http://www.speedwaymotors.com/HEI-Advance-Curve-Kit,740.html)

Thats all I got
Daniel
Mash on it
Title: Re: Vaccume advance?
Post by: SoCalPSD on March 15, 2012, 08:38:46 AM
On every gm style hei I have i never use it but I do change the springs on the mechanical advance to a lighter spring. When using the lighter springs I drop the timing to 12* at idle opposed to 15* with the firmer springs.

Fat fingered from the phone-  Corey
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