DIY vac advance w/spring -- SUCCESS! (long) - Bulletin Board
Click Banner for Details on this Classified

[General | Members | C900 | 9000 | NG900 & OG93 | 93 | 95 | NG95 | 99 | Sonett | Vintage Models | Performance | Detail | Clubs & SOC | Other Cars | Books Movies & Music | Chat | FAQs | Gifts | Member Photo Galleries | Member Directory | Classifieds | Service/Mechs | Manuals | *Buddy Registry | *Mileage Registry | Polls | What's New | Raffle | Photo of the Month | Sponsors]

Performance Bulletin Board
(Search Author's Posts: e.g. Keyword:Author)*Members Only

[Main Performance Bulletin Board | Post Followup | BBFAQ ] [ Prev by Date ] [ Next by Date ] Member Login / Signup [Most Recently Edited Photo Galleries]
DIY vac advance w/spring -- SUCCESS! (long)
Posted by Notnoel [Email] (#23) [Profile/Gallery] (more from Notnoel) on Sat, 23 Dec 2006 09:56:36
Alert me when someone posts in this thread:

Thanks to Jak, MS, and 900 aero! Just installed my modded capsule and it works like a charm! I drilled out the stop and modified it as described elsewhere. Then drilled a hole in the top and bottom of the mount to attach a small rod parallel to the capsule (to attach one end of the springs to). I then drilled another small hole in the actuator to attach the other end of the spring to.

For the springs, I cannibalized an old 3.5" disk drive. These springs are stainless steel and about a 1/2" long and a 1/16" in diameter. They are pretty stiff and design to work under tension (to pop the disk out of the drive). I slipped my thumbnail into the spring and stretched out the end of the spring I planned to discard, cut off the excess, and bent the end into a hook. Next I attached the hook to the rod and the hole in the actuator arm so that the spring was under slight tension.

Next came bench testing using my boost gauge. Turns out one spring did not provide enough tension, so I added two in parallel. Under this set-up, the actuator began to move at about .2 bar and closed the stock gap at about .4 to .5 bar. I determined that the springs could only go on the underside of the actuator arm due to clearance issues. Since the modified gap of about 2 mm is twice the stock, it seemed like I was pretty close to where I wanted to be. So I modified the retard stop to an adjustable cam, set it for about 2 mm and tried my bench test. It hit the stop right at 1 bar, so I installed it in the car.

I set the timing at idle at 20 degrees, hooked up the gauge and vacuum hose and began incrementally pumping up the simulated boost. The timing retarded smoothly beginning at about .2 bar and landing at 10 degrees at 1 bar just as in the bench test. Nirvana on the test drive.

I don't seem to be boosting as far into the red as before, but I (still) haven't received my 3.0 bar FPR from the guy I bought it from on Ebay yet. I suspect that I need more fuel to compensate for the extra retard I've got now. I'm going to wait until that comes to fool around with really dialing this in.

I can't figure out how to post a photograph, so I'm going to email it to Jak since I can get his email address from his website. Thanks again to all of you for your help. This site (and you guys) rock!

posted by 70.21.6...

Posts in this Thread:
Alert me when someone posts in this thread:

Post a Followup

No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.

Name: Member Login / Signup [Most Recently Edited Photo Galleries]
E-Mail: (Optional)
Re-Enter E-Mail: (Confidential & Secure - Not revealed to other users!)
Note: Please check your spam folder for BB responses.
If you use GMail, follow these instructions from Google so that they appear in your regular inbox.


Posting rules are simple - No for sale/wanted ads or live auctions may be here - use the classifieds.
You may not cross-post your message to multiple BBs.
Personal attacks, insults, or flaming are not allowed.
Site Members do not see any red text, inline ad links, bottom of page anchor ads, box ads, or anti-spam check.

Message: (please no for sale/wanted classifieds - post those in the TSN Classifieds)
To add inline links to your post, use [link][endlink] or use the Optional fields below.
To add inline images to your post, use [img][endimg] or use the Optional Image Link field below.

Optional Link: (e.g.
To promote your own Saab site here, you must have a link back to The Saab Network.
Link Title: (Optional)
Optional Image Link: (e.g.

The content on this site may not be republished without permission. Copyright © 1988-2018 - The Saab Network -
For usage guidelines, see the Mission and Purpose Page.
[Contact | Site Map | on Facebook | on Twitter | Shop Amazon via TSN | Site Donations]

This is a moderated bulletin board - Posting is a privilege, not a right. Unsolicited commercial postings are not allowed (no Spam). Please, no For Sale or Wanted postings, SERIOUSLY. Classifieds are to be listed in The Saab Network Classifieds pages. This is a problem solving forum for over 250,000 Saab owners, so expect to see problems discussed here even though our cars are generally very reliable. This is not an anything goes type of forum. has been a moderated forum since 1988. For usage guidelines, see the Mission and Purpose Page. Please remember that you are not anonymous. Site Contact | Site Donations | Other Sites by SP -
Your address is: - Using CCBot/2.0 ( - Logged.

Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all the Site Membership Benefits!