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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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 Posted: Fri Jan 25, 2013 2:16 am Post subject: new timing light |
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Hi Guys,
Bought a new timing light the other day, bought a gunson advance.
i reset my timing yesterday, but just to be sure, i want to check with you guys if i did it right.
7.5 BTDC without vac.
30 BTDC full advance.
SVDA dist, 31pict3 carb, gunson advance timing light, heineken beer.
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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drs1023
Samba Member
Joined: October 20, 2011
Posts: 1682
Location: Georgia, USA
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| Posted: Fri Jan 25, 2013 5:52 am Post subject: |
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I run a 34 series carburetor with an SVDA. Many on this forum will caution against using the 30 seeries carbs due to there not being enough vacuum for the SVDA to operate to its full potential. Hopefully, someone else will know the particulars of this application better than I do.
The numbers below look right. Full advance should happen around 3200 ~ 3500 rpm.
Don't forget to recycle the "Heinny" can |
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Glenn 
Mr. 010
Joined: December 25, 2001
Posts: 76935
Location: Sneaking up behind you
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| Posted: Fri Jan 25, 2013 6:25 am Post subject: |
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The 034 (205zb) SVDA was never intended to work with a 30PICT-x carb.
You'd be better off with a 019 mechanical.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Fri Jan 25, 2013 12:15 pm Post subject: |
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thanx, will be looking for a 019 soon, after i get some new tires.
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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JerryMCarter1
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Joined: January 07, 2007
Posts: 6199
Location: N.W. Phoenix
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| Posted: Fri Jan 25, 2013 4:11 pm Post subject: |
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Experience always triumphs over hearsay and You get to select which theory to believe |
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slione
Samba Member
Joined: June 18, 2011
Posts: 180
Location: NJ
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| Posted: Fri Jan 25, 2013 4:20 pm Post subject: |
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Great chart Jerry!
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1974 SB Vert  - Getting there, slowly but surely |
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JerryMCarter1
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Joined: January 07, 2007
Posts: 6199
Location: N.W. Phoenix
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| Posted: Fri Jan 25, 2013 4:26 pm Post subject: |
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I stole it here on the Samba
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slione
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Joined: June 18, 2011
Posts: 180
Location: NJ
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| Posted: Fri Jan 25, 2013 4:58 pm Post subject: |
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| JerryMCarter1 wrote: |
| I stole it here on the Samba |
You mean "liberated." 
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Fri Jan 25, 2013 8:34 pm Post subject: Re: new timing light |
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| hobbybob517 wrote: |
i reset my timing yesterday, but just to be sure, i want to check with you guys if i did it right.
7.5 BTDC without vac.
30 BTDC full advance.
SVDA dist |
Can you post the model# stamped into the side of the distributor body? Or if you bought it recently, the make and model? There are more than one SVDA from VW.
To see if your distributor is working:
Test1: At idle, disconnect and plug all distributor hoses and note the timing (eg. 7.5BTDC). Connect the vacuum advance hose to the intake manifold port or one of the rear facing ports on the carb that have strong vacuum at idle. This will force the vacuum advance to max advance. Note the change in the timing. If you have an advance timing light you can dial back the advance to the idle timing and note the reading. This is how much advance your vacuum advance is giving.
Test2: With distributor vacuum hoses disconnected and plugged, rev the engine to max total advance (eg. 30BTDC) and note the timing. Do the same test with the vacuum advance hose connected to the carb left side vacuum port. Rev the engine up and maintain the high rpm with the smallest carb opening possible. This will provide max vacuum at max advance. A working SVDA distributor with the proper level of vacuum advance should add 7~12deg of advance to the total advance measured earlier. 40~45BTDC readings with mechanical + vacuum advance @3500rpm is not unusual.
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AshMan40
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'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Sat Jan 26, 2013 1:07 am Post subject: |
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| JerryMCarter1 wrote: |
| I stole it here on the Samba |
thanx, but i have a 31pict3 not a 34, mine is only a 1300 DP.
@Ashman40
at idle vaccuum plugged, it reads 7.5 BTDC, this is also how i timed it static.
with vaccuum at about 3000-3500 rpm it goes to about 30 degrees BTDC.
before i got the timing light it was about 60 degrees off, amazingly it ran quite well with the occasional stumble on acceleration.
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Sat Jan 26, 2013 3:16 am Post subject: |
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| hobbybob517 wrote: |
| at idle vaccuum plugged, it reads 7.5 BTDC, this is also how i timed it static. |
What were the results of Test1? How much vacuum advance was added during the test when it was plugged into the intake vacuum?
| hobbybob517 wrote: |
| with vaccuum at about 3000-3500 rpm it goes to about 30 degrees BTDC. |
What were the rest of Test2 results? 30BTDC with vacuum, how much of a difference in timing w/o vacuum advance?
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AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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hobbybob517
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Location: Netherlands
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| Posted: Sat Jan 26, 2013 10:03 am Post subject: |
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i'm not sure i didn't write it down, thought only these 2 mattered, 7.5 btdc at idle 30 btdc full advance.
anything else i should have checked?
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
| SBD wrote: |
3 million rpm? Well there's your problem! No wonder it blew up! |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15985
Location: North Florida, USA
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| Posted: Sat Jan 26, 2013 7:27 pm Post subject: |
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| hobbybob517 wrote: |
at idle vaccuum plugged, it reads 7.5 BTDC, this is also how i timed it static.
with vaccuum at about 3000-3500 rpm it goes to about 30 degrees BTDC.
before i got the timing light it was about 60 degrees off, amazingly it ran quite well with the occasional stumble on acceleration.
<...>
thought only these 2 mattered, 7.5 btdc at idle 30 btdc full advance. |
30BTDC at full advance (initial + mechanical) is a safety guideline and is done w/o vacuum advance connected. Much more than this and you could "detonate" your engine.
Note that based on your feedback you haven't measured this yet... you measured initial + mechanical + vacuum. Not the same.
I suggested you measure both (with and w/o vacuum) and determine the difference so you would understand how much additional vacuum advance your carb+distributor combo could give.
7.5BTDC is typically a good starting point for SVDAs. If you have a good working VW original SVDA distributor that calls for 7.5BTDC at idle you can usually set it and not worry about the 30BTDC @3500rpm. It really is only the low quality manufactured aftermarket distributors that you want to test the max advance. Some of these low quality distributors when set to 30BTDC @3500rpm will end up having an idle timing of as little as 0TDC or as much as 15BTDC. That's a manufacture variance of 15deg! Which is why you test them to make sure they aren't going to blow up your engine.
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AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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hobbybob517
Samba Member
Joined: June 02, 2011
Posts: 1194
Location: Netherlands
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| Posted: Sun Jan 27, 2013 2:20 am Post subject: |
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ok thanx,
will go out to test it again.
it is an orrigional VW dist.
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THE BUILD http://www.thesamba.com/vw/forum/viewtopic.php
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3 million rpm? Well there's your problem! No wonder it blew up! |
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