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Limiting Vacuum Advance BEFORE BOOST?
Posted by: kmart356 ()
Date: March 08, 2018 07:12AM

Greetings. On my "street performance" turbo engine I am running a custom (319) distributor with 18* mech advance (curve very similar to 1110311).
with a vacuum advance that is providing 23* @ 15in-HG. I want to limit the vacuum advance to 7-10* to see if that stops a bit of pinging when pushing the go pedal. I have read some posts by members that have done this on the factory vac advance canister, but cannot find with search.

I have some ideas on how to limit the travel of the vac adv arm, but I always like to learn from previous efforts. If you have done this and have photos... please do post them before I hack up my parts smiling bouncing smiley

Thank you kindly.

Ken
'62 Spyder Coupe
Florida





Edited 2 time(s). Last edit at 03/09/2018 08:16AM by MattNall.

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Re: Limiting Vacuum Advance?
Posted by: MattNall ()
Date: March 08, 2018 07:25AM

Drill a hole in the arm and use a pin to limit the pull distance





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Limiting Vacuum Advance?
Posted by: jjohnsonjo ()
Date: March 08, 2018 07:35AM

Ken I added a set screw on my A/R to limit the boost function and can post a pic, but it probably won't help you since you are going the opposite direction. Some guys just crush the canister in a vice, but that's kind of permanent.

If it were me I would cut something for a shim, then slide in the "u" shaped hole in the points arm where it goes into the canister, that will limit the travel. Then you can tape them in place and see what works for you. If you find the magic size then epoxy it in place.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Limiting Vacuum Advance?
Posted by: Nickshu ()
Date: March 08, 2018 08:24AM

A Safeguard system can provide customized advance and retard perfect for turbo engines. Sold by AmericanPi (Ray Sedman). You block off the vacuum line to the retard can and the look is almost completely stock except for a knock sensor that goes by the left head intake. Mine is mounted under the back seat. If you want it can also T into your boost gauge line and will tailor the advance to recorded boost or vacuum.

Nick
_______________________________________________________________________
1964 Monza Spyder Convertible #435 - Rotisserie restored - Check out my restoration thread here: [corvaircenter.com]
Recreational Mechanic/CORSA Member/COG Supporting Member/US Navy Veteran
Other fun car: Porsche 911 GT3
Boring daily drivers
Northern Colorado, USA

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: gnvair ()
Date: March 08, 2018 09:11AM

There are other ways of tailoring the curve these days that are half the cost of the Safeguard. Not every one wants to spend that much. I have made advance plate limiters on different cars over the years.

Lee J

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: kmart356 ()
Date: March 08, 2018 09:28AM

Thank you for the feedback gents. This gives me some alternatives. I was thinking a limiter inside that U shaped arm as J.O. mentions.

Yes Nick, I am running one of the older Safeguard units (no advance, just boost retard) and fashioned a "fixed" arm to replace the retard canister - see photo. It idles better and accelerates more smoothly with the vacuum advance on there now, just want to try this last little tweak limiting how much advance.



Ken
'62 Spyder Coupe
Florida


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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: vairmech ()
Date: March 08, 2018 04:11PM

You can bend the stop on the vac advance.

Ken Hand
Handy Car Care
248 613 8586

Vairmech@aol.com

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: MattNall ()
Date: March 08, 2018 04:28PM

kmart356 Wrote:
-------------------------------------------------------

> I am running one of the older Safeguard
> units (no advance, just boost retard) and
> fashioned a "fixed" arm to replace the retard
> canister

> It idles better and
> accelerates more smoothly with the vacuum advance
> on there now,
================================================================

You say your curve is similar to a 311..but only 18 vs 20 deg. 311 doesn't go full on until 4200 rpm. Our engines only rev to 5500-5800 in stock form. We want boost ASAP like 2500 or sooner.

What is the initial mechanical timing?

Why not just curve the Dist. to go 36-38 D-BTDC say at 2000 rpm with an initial mech setting say 14 BTDC [ easy start... low idle! ]

Then let the SG do it's work if ping is sensed? Forget a VA, which is only for low throttle openings.....Cruise MPG!!

It is pretty much agreed on that Most All Vair engines 8-9 to 1 CR need 29 deg. BTDC while under boost





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: 63turbo ()
Date: March 08, 2018 05:27PM

Matt- On the fuel that we can get today, 36 degrees is way too much at 2000 rpm
... GM tested the 1963 Spyder using 115 octane to determine maximum best torque. Here's some numbers at only 1% torque loss.

1200rpm 30deg
2000rpm 31deg
2400rpm 30deg
2800rpm 25deg
3200rpm 25deg
3600rpm 30deg
4000rpm 32deg
4400rpm 37deg
4800rpm 39deg
5200rpm 44deg

You want to try making a curve like that using only weights and springs and no
VA, good luck! I can personally vouch for the numbers above as my car (when it was running of course) were very close to the above using a combination of vacuum advance and rpm advance... anything more than 30 degrees @ 2000 rpm the car runs rough and wont warm up and doesn't make anymore power there anyways, and it is the same story at lower rpms. I know that kmart356 initially had a timing curve much like what you are advocating, and it wasn't working that well for him... the safeguard was telling him that it was taking out timing,
and that's how he ended up with his new custom distributor curve.

------------------------------------

Kevin Nash
Friday Harbor Washington
63 Spyder, Daily driver, EFI read about my project here: [corvaircenter.com]
first test start on EFI here:[www.youtube.com]
first official EFI boost test here:[www.youtube.com]
My new fan! [corvaircenter.com]
engine less 62 Spyder
Canadian 64 Monza Parts car



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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: MattNall ()
Date: March 08, 2018 05:34PM

Well, I stick with my setup on 90 octane UL

Time for Video shootouts!







MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: kmart356 ()
Date: March 08, 2018 07:58PM

Maybe I confused matters when I mentioned the 311. My distributor has 18* mech advance and is all in by 3000rpm. Static timing is 12* so full advance is 30*. The Safeguard is barely taking any timing out - based on my settings I should be getting 28* under full boost.

The addition of the vacuum advance helps idle and low throttle response. The slight ping I am trying to solve is pre-boost, during the transition from high vacuum to low,zero vacuum condition. I am going to limit the vac advance to 10-12* and do more testing. Once I get rid of the pre-boost ping thing, I will push timing up a bit with the SG covering any needed boost retard.

Ken
'62 Spyder Coupe
Florida


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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: MattNall ()
Date: March 08, 2018 08:13PM

AHH sounds much better... to me!! gg





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: jjohnsonjo ()
Date: March 09, 2018 07:14AM

Ken I hope this works the way you want. I had a similar situation with mine, I would get some light pinging under load. I would hear it mostly when I hit the gas near a wall or highway divider. The problem wasn't so much the full vacuum advance, but the partial advance. I ended up backing 2 degrees out of the static and left the full advance (A/R) go all the way. If I was only running a straight vacuum advance I think I would search for one with a stronger spring so it isn't as aggressive at partial vacuum.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Limiting Vacuum Advance UNDER BOOST?
Posted by: kmart356 ()
Date: March 09, 2018 08:04AM

Thanks for the additional insight J.O. What you describe is pretty close to what I am experiencing.

Ken
'62 Spyder Coupe
Florida


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Re: Limiting Vacuum Advance BEFORE BOOST?
Posted by: Nickshu ()
Date: March 09, 2018 09:27AM

Ken would a newer model Safeguard box that does advance and retard be plug and play on your current one? Seems like that would be alot easier and more accurate.

Nick
_______________________________________________________________________
1964 Monza Spyder Convertible #435 - Rotisserie restored - Check out my restoration thread here: [corvaircenter.com]
Recreational Mechanic/CORSA Member/COG Supporting Member/US Navy Veteran
Other fun car: Porsche 911 GT3
Boring daily drivers
Northern Colorado, USA

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Re: Limiting Vacuum Advance BEFORE BOOST?
Posted by: MattNall ()
Date: March 09, 2018 10:15AM

VA adjusting
Posted by: MattNall
Date: August 21, 2007

There are so many different PN's of Vair VA's and they were designed for use in the 60's

Adjust YOURS..

take it off lay in vice and using a proper sized SOCKET [ 1/2"??]& Hammer

Dimple the flat area around the hose nipple...

lower it 1/8" first and test on the car....

if pinging comes back... lower it another 1/8"

IF you have access to a Mighty Vac or other vacuum pump with gauge...you can test the unit Before / during and after

It's a simple no brainer..





MODERATOR
Sea Mountain, between Charleston Harbor and Coos Bay! SW Oregon Coast
Click HERE for My Website...Click HERE for My TechPages!
..............................110-PG.................................................Webered-Turbo

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Re: Limiting Vacuum Advance BEFORE BOOST?
Posted by: jjohnsonjo ()
Date: March 09, 2018 10:40AM

Nickshu Wrote:
-------------------------------------------------------
> Ken would a newer model Safeguard box that does
> advance and retard be plug and play on your
> current one? Seems like that would be alot easier
> and more accurate.

Nick, I'm your enjoying yours. Its a great product. I spent a lot of time talking to Ray when he was designing and improving the product. I'm more of an electronics guy than a car guy. He seemed to have a lot more time to BS then than he does now. I already have two modern turbo cars, three if you count my son's WRX, that all you need to do is step on the gas and the computer figures out the rest. Playing with this stuff the old fashion way is part of the fun and challenge for me.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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Re: Limiting Vacuum Advance BEFORE BOOST?
Posted by: thewolfe ()
Date: March 10, 2018 09:27AM

The newer safeguard will do either vacuum advance or boost retard but not both. You have to pick one or the other. It is set with a switch on the unit.

Nate Wolfe
Portland OR
65 Corsa 180

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Re: Limiting Vacuum Advance BEFORE BOOST?
Posted by: toms73novass ()
Date: March 10, 2018 12:17PM

Since it has been brought up in this thread....

What is the difference between ordering a safeguard from Ray, American Pi or the one from J&S electronics

[www.jandssafeguard.com]

Getting a response from Ray is not easy!

-Tom


63' Monza Spyder Convertable (in process) MY Build Thread
65' Monza MY Build Thread
73' NovaSS 454 Big block
86' BMW 325es
98' Dodge 2500 12v Cummins Diesel with 1200 lb torque!
98' VW Jetta TDI, for daughter
01' Audi Allroad Stage 3 twin turbo

NFCC
Grand Island, NY

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Re: Limiting Vacuum Advance BEFORE BOOST?
Posted by: jjohnsonjo ()
Date: March 10, 2018 12:44PM

The S in J&S is Ray. Its just another way to market.

J.O.

65 Corsa Turbo Vert
79 Honda XL 500S
69 Honda CL 160 D
2010 BMW F 650 GS
2003 Bounder 36D
2013 KIA Optima SX turbo-AKA ZIPPY (wife,s car)
69 Newport Holiday Sailboat
Baja 150 dune buggy cart
Coleman HS 500 UTV
2016 KIA Sorento SXL Turbo

Bethlehem,Pa

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