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robin.richard
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Joined: February 17, 2012
Posts: 497
Location: V. Beach VA
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 Posted: Mon Feb 12, 2018 4:38 pm Post subject: Testing a vacuum advance without timing light |
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Okay, I guess I'll ask question since I could not readily find the answer.
How can one test, or make sure his vacuum advance is advancing properly without a fancy (expensive) timing light?
I just changed my distributor from a 009 to a proper vacuum advance distributor a week ago. I run a SOLEX 30 PICT 1 carb in my 1600 SP and now use a 113 905 205 K vacuum distributor. Before I installed the distributor I cleaned and lubed it, replaced the points, condenser, rotor, and cap. Gaped the point @.016. Sucked on the vacuum can to make sure the arm would move and it would hold. Static timed @ 7.5 BTDC. The engine runs very good. No issues noticed. No noticeable flat spots or hesitation at takeoff. Something that I would notice occasionally with the 009 on takeoff. So I guess I just assume the distributor is good? Any suggestions to test without timing light?
Thanks.
-Rich
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DubStyle
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robin.richard
Samba Member
Joined: February 17, 2012
Posts: 497
Location: V. Beach VA
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| Posted: Mon Feb 12, 2018 5:03 pm Post subject: Re: Testing a vacuum advance without timing light |
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Sorry for any confusion in my post.
I used a static timing light to set the timing @ 7.5 BTDC, but was not sure how to test to see if the distributor is advancing properly without one of those fancy variable speed timing light guns.
Looking for tricks to see if it's advancing properly @ ~3000 RPMs?
-Rich
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busdaddy
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Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Mon Feb 12, 2018 5:35 pm Post subject: Re: Testing a vacuum advance without timing light |
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| robin.richard wrote: |
Sorry for any confusion in my post.
I used a static timing light to set the timing @ 7.5 BTDC, but was not sure how to test to see if the distributor is advancing properly without one of those fancy variable speed timing light guns.
Looking for tricks to see if it's advancing properly @ ~3000 RPMs?
-Rich |
Not a whole lot you can do if you lack X-ray vision, a strobe is the only option for mortals. You could pull off the vacuum line @3K RPM and see if the RPM drops a bit, that will indicate the advance was sucked in some, but running static at 3K there won't be too much (or any) advance, that really only happens under load with throttle openings much higher than you can duplicate in the driveway.
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Clara 
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Joined: June 14, 2003
Posts: 12401
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| Posted: Mon Feb 12, 2018 7:21 pm Post subject: Re: Testing a vacuum advance without timing light |
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| busdaddy wrote: |
| robin.richard wrote: |
Sorry for any confusion in my post.
I used a static timing light to set the timing @ 7.5 BTDC, but was not sure how to test to see if the distributor is advancing properly without one of those fancy variable speed timing light guns.
Looking for tricks to see if it's advancing properly @ ~3000 RPMs?
-Rich |
Not a whole lot you can do if you lack X-ray vision, a strobe is the only option for mortals. You could pull off the vacuum line @3K RPM and see if the RPM drops a bit, that will indicate the advance was sucked in some, but running static at 3K there won't be too much (or any) advance, that really only happens under load with throttle openings much higher than you can duplicate in the driveway. |
You can actually tell by ear if the timing is not advancing, as it will sound retarded. It is like the note is flat. If you don't know what that sounds like I can't explain it. Buy a strobe light timing gun and use it. Good to check the advance is advancing with a mechanical advance as well at every tune up. Those can stick, which you can tell is happening if you know what it sounds like when running retarded. Then you can manually set it so it is where it should be at advanced, and swap it out when you get home. |
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Glenn
Mr. 010
Joined: December 25, 2001
Posts: 76940
Location: Sneaking up behind you
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| Posted: Mon Feb 12, 2018 7:29 pm Post subject: Re: Testing a vacuum advance without timing light |
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Disconnect the hose from the carb. Remove the distributor cap. suck on the hose, the points should move counter clockwise. If they don't, it's not advancing.
BTW... you can test it with a timing light since the engine really needs to be under load and not at idle.
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AngelBoy
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| Posted: Tue Feb 13, 2018 6:22 pm Post subject: Re: Testing a vacuum advance without timing light |
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If it's running OK, meaning it accelerates like it should, you have to have the spark advancing. It it wasn't working it would accelerate like it was running on three cylinders. Totally dogged out.
However, if I were you, I'd invest in a $30 timing light. Here's why; sometimes those old distributors can advance too much. Which will make you think everything is fine. The car will have a little extra get up and go.
But, I is running hot with the advance going too far. I had an old 205T that was advancing to almost 50 degrees. You need to be able to make sure your distributor isn't advancing too much. Shouldn't go past about 30 degrees???
Not good.
Buy a timing light. You need it anyway. Good luck........
Ray in Temecula |
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Tue Feb 13, 2018 7:29 pm Post subject: Re: Testing a vacuum advance without timing light |
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On a vacuum only distributor there is no way it should advance to 50 degrees. It either had the wrong vacuum canister or return spring on it. Now an SVDA or a DVDA distributor can deliver some strange results.
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wcfvw69
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Joined: June 10, 2004
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| Posted: Tue Feb 13, 2018 8:02 pm Post subject: Re: Testing a vacuum advance without timing light |
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The correct vacuum can on a 205K will advance the timing approx 24* where a 205T correct vacuum canister will advance the timing 30*. There's no mechanical advance obviously with an SVA.
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Glenn
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| Posted: Tue Feb 13, 2018 8:08 pm Post subject: Re: Testing a vacuum advance without timing light |
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I don't see how the wrong spring can control the total advance, the vacuum canister does. The spring controls the "curve" or rate of advance from none to maximum.
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Harleyelf
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Joined: April 23, 2009
Posts: 1572
Location: Appleton, WI
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| Posted: Tue Feb 13, 2018 10:37 pm Post subject: Re: Testing a vacuum advance without timing light |
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| A wrong spring could change the rate of change or the rpm at which full advance is attained, but I don't see how it could expand the advance range. |
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AngelBoy
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Location: Oceanside, CA
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| Posted: Wed Feb 14, 2018 9:18 am Post subject: Re: Testing a vacuum advance without timing light |
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| All I'm saying is that robin.richards should get a timing light because he should care about the timing at the bottom side of the rpm curve, and at the top side too. The only way to do that is with a timing light; and those old distributors can get funky. |
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Lind
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Location: idaho
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| Posted: Wed Feb 14, 2018 11:55 am Post subject: Re: Testing a vacuum advance without timing light |
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| robin.richard wrote: |
Okay, I guess I'll ask question since I could not readily find the answer.
How can one test, or make sure his vacuum advance is advancing properly without a fancy (expensive) timing light?
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I don't know what your definition of expensive or fancy is, but this is the light that I use, and I consider it to be a cheap and essential tool for tuning your VW. The cost is less than an hour of time at most any auto shop.
http://www.sears.com/craftsman-advanced-timing-light/p-00914065000P
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srfndoc
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2Pack
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| Posted: Wed Feb 14, 2018 1:19 pm Post subject: Re: Testing a vacuum advance without timing light |
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| robin.richard wrote: |
Okay, I guess I'll ask question since I could not readily find the answer.
How can one test, or make sure his vacuum advance is advancing properly without a fancy (expensive) timing light?
I just changed my distributor from a 009 to a proper vacuum advance distributor a week ago. I run a SOLEX 30 PICT 1 carb in my 1600 SP and now use a 113 905 205 K vacuum distributor. Before I installed the distributor I cleaned and lubed it, replaced the points, condenser, rotor, and cap. Gaped the point @.016. Sucked on the vacuum can to make sure the arm would move and it would hold. Static timed @ 7.5 BTDC. The engine runs very good. No issues noticed. No noticeable flat spots or hesitation at takeoff. Something that I would notice occasionally with the 009 on takeoff. So I guess I just assume the distributor is good? Any suggestions to test without timing light?
Thanks.
-Rich |
What I've done before to check full advance on a vacuum advance distributor is make marks on the crank pulley corresponding to the upper and lower limit of full advance. Then I verify that the timing mark moves between those two marks at high RPMs using a normal static timing light. You can look the full advance limits up in the VW workshop manual. I have a way to mark the pulley that I like too so post back if you need that info.
Clarification: when I say static timing light I mean a strobe light without the adjustable advance.
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sjbartnik
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Joined: September 01, 2011
Posts: 5998
Location: Brooklyn
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| Posted: Wed Feb 14, 2018 1:32 pm Post subject: Re: Testing a vacuum advance without timing light |
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Strobe timing lights are neither fancy nor expensive
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tasb
The Distributor Distributor
Joined: April 27, 2002
Posts: 6371
Location: Pentwater, Michigan
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| Posted: Wed Feb 14, 2018 10:05 pm Post subject: Re: Testing a vacuum advance without timing light |
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ok, let me clarify my statement earlier that having the wrong spring will cause the distributor to act other than normal but does not effect total advance.
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Bruce Amacker
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| Posted: Thu Feb 15, 2018 7:17 am Post subject: Re: Testing a vacuum advance without timing light |
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[quote="2Pack"]
| robin.richard wrote: |
Clarification: when I say static timing light I mean a strobe light without the adjustable advance. |
I also do not like adjustable timing lights. First, you can inadvertently turn the knob completely messing up your readings.
Second, I had a Snap-On adjustable light years ago that was faulty and the knob setting was not even close to what the actual timing variation was.
Regular old inductive lights for me.
Sidebar: Don't forget to verify TDC using a piston stop tool. If you're running a stock pulley you probably don't know exactly which pulley it is/what the marks mean because there are so many pulleys. Second, if you're running an aluminum marked pulley, every one I've checked was off by 2° or more. Some were off 4-5°, none were dead on. Whoever is slapping on the decal doesn't give a rat's ass if it's off a little bit. If I'm working on someone's car and they want the timing checked, step 1 is verifying TDC. You're wasting your time if you don't do this.
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BulliBill
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Joined: July 09, 2004
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Location: St Charles, MO
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| Posted: Thu Feb 15, 2018 7:34 am Post subject: Re: Testing a vacuum advance without timing light |
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Hey Bruce,
Is this "piston stop tool" that you mentioned an actual precision tool for this purpose or just a pencil or dowel inserted thru a removed spark plug resting on the piston? If there is a tool for this purpose that works on our older air-cooled heads/pistons, I'll bet lots of us would be interested in it. Any sources or web links to info/cost? I've tried to verify marking on pulleys before to locate TDC with a dowel, but a real precise tool designed for this chore would be cool to have! Thanks!
Bill Bowman
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brettsvw
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| Posted: Thu Feb 15, 2018 8:07 am Post subject: Re: Testing a vacuum advance without timing light |
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| BulliBill wrote: |
Hey Bruce,
Is this "piston stop tool" that you mentioned an actual precision tool for this purpose or just a pencil or dowel inserted thru a removed spark plug resting on the piston? If there is a tool for this purpose that works on our older air-cooled heads/pistons, I'll bet lots of us would be interested in it. Any sources or web links to info/cost? I've tried to verify marking on pulleys before to locate TDC with a dowel, but a real precise tool designed for this chore would be cool to have! Thanks!
Bill Bowman |
I used a homemade tool that the owner of a VW shop made in the 60s.
I will try to explain without confusion. Young dumb 20somthing kid did not take a pic. LOL
Using an old sparkplug dismantle down to the metal treaded part. Devise a springloaded rod similar to a ballpoint pin. I remember two springs.
Insert into sparkplug opening. When piston hits rod, rod would move with piston up and down as an indicator. Worked very well.
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