TheSamba.com :: View topic - Timing gun changes RPM when trigged pulled

Sat Nov 17, 2018 3:29 pm

So my timing light makes my engine rev higher when I pull the trigger to check timing...Any reason why this is? I can't get a good time on it if it's revving it higher....Type IV, Electronic Distributor, Weber 40's

Sat Nov 17, 2018 3:34 pm

Is the timing light new? Some new ones you can set the advance or something like that so read the instruction manual or look at the gun for something strange.

Sat Nov 17, 2018 3:40 pm

Starbucket wrote: Is the timing light new? Some new ones you can set the advance or something like that so read the instruction manual or look at the gun for something strange.

Nope, I've had it for a few months now.

Sat Nov 17, 2018 4:28 pm

Not to mention, when I set it with a static light, the location changes...I can hook the light up to a ground and then negative terminal on the coil and each time I do it, I can turn the distributor completely in a circle without it lighting up, then all of a sudden the red bulb will light. i'm so confused

Sat Nov 17, 2018 5:07 pm

74superTN wrote: Not to mention, when I set it with a static light, the location changes...I can hook the light up to a ground and then negative terminal on the coil and each time I do it, I can turn the distributor completely in a circle without it lighting up, then all of a sudden the red bulb will light. i'm so confused

you aren't going to be able to set the timing statically very readily with many units. As for timing it while the engine is running, remove the vacuum hose(s) from the distributor and rev it up until the timing quits advancing (at around 3500 rpms) and adjust the timing to 28° BTDC.

Sat Nov 17, 2018 6:08 pm

Is it inductive pickup or pass through?

Sat Nov 17, 2018 6:29 pm

Abscate wrote: Is it inductive pickup or pass through?
Yeah, and if inductive where do you have the alligator clip black and red leads connected?

Sat Nov 17, 2018 6:36 pm

busdaddy wrote: Abscate wrote: Is it inductive pickup or pass through?
Yeah, and if inductive where do you have the alligator clip black and red leads connected?

I honestly don't know what that means but the alligator clip is grounded and the red is on the negative of the coil

Sat Nov 17, 2018 6:58 pm

74superTN wrote: busdaddy wrote: Abscate wrote: Is it inductive pickup or pass through?
Yeah, and if inductive where do you have the alligator clip black and red leads connected?

I honestly don't know what that means but the alligator clip is grounded and the red is on the negative of the coil
If you only got it a while ago maybe the instructions are still around somewhere?
Does it have a third larger clamp that goes onto the #1 spark plug wire? How about a picture or link to one for sale?

Sat Nov 17, 2018 7:18 pm

Attach the red to the battery +

Sounds like you are affecting the spark by attaching at the coil.

All that a basic timing light needs is 12v power (the black and red alligator clips) and a signal from the clamp over the #1 spark plug wire.

Sat Nov 17, 2018 7:22 pm

WhirledTraveller wrote: Attach the red to the battery +

Sounds like you are affecting the spark by attaching at the coil.

All that a basic timing light needs is 12v power (the black and red alligator clips) and a signal from the clamp over the #1 spark plug wire.
One would assume, but we haven't seen what kind of light we are talking about yet, there's multiple options and connecting some directly to the battery will end badly.

Sat Nov 17, 2018 7:49 pm

If you have a timing light/gun with three leads,use the battery posts for
+ & - & clip the inductive clamp around the #1 spark plug wire, if the
strobe light seems to misfire you may have to move the inductive clamp
up or down the wire to lose a false signal from one of the other plug wires.

Sat Nov 17, 2018 8:40 pm

74superTN wrote: Type IV, Electronic Distributor.

Do you mean Hall Effect factory electronic distributor?
Be very careful if so, Hall Effect has specific instructions in your Bentley.
Colin

Sat Nov 17, 2018 9:25 pm

It's a Petronix Distributor and the strobe doesn't seem to misfire, it just speeds up my motor when I pull the trigger. It's a three cable gun, red, black, and the one that goes on the #1 spark plug wire. I put red on the positive coil, black on a ground on the engine, and the other on the spark plug wire. Right now all it's doing is trying to crank, I can't actually get it idling and this all of a sudden happen within two days. No to mention when I did get it running for a second yesterday, I had no spark on #1

Sat Nov 17, 2018 9:27 pm

And here's the light I'm using
https://shop.advanceautoparts.com/p/actron-inductive-timing-light-cp7527/9090009-P

Sat Nov 17, 2018 11:58 pm

The manual says Quote: 4. Connect RED and BLACK Battery Clips on Negative Ground Electrical Systems.
· Connect RED to positive (+) battery post. · Connect BLACK to engine ground.

Try doing that, should work fine. If you have the inductive 7527 then it's as basic as they come - just an on button. As Wildthings said, time timing at maximum advance, vacuum hose off, to 28 ° BTDC.

I used one of these when I'm setting the timing statically:

Sun Nov 18, 2018 12:09 am

74superTN wrote: Not to mention, when I set it with a static light, the location changes...I can hook the light up to a ground and then negative terminal on the coil and each time I do it, I can turn the distributor completely in a circle without it lighting up, then all of a sudden the red bulb will light. i'm so confused

Can you time a Petronix statically like this? I'm not sure you can

Sun Nov 18, 2018 7:01 am

Also, this is in a Vanagon, so I can't reach the battery terminals.

Sun Nov 18, 2018 9:11 am

Abscate wrote: 74superTN wrote: Not to mention, when I set it with a static light, the location changes...I can hook the light up to a ground and then negative terminal on the coil and each time I do it, I can turn the distributor completely in a circle without it lighting up, then all of a sudden the red bulb will light. i'm so confused

Can you time a Petronix statically like this? I'm not sure you can Not sure of Pertronix, but you can with a Compufire which I believe is similar.

Sun Nov 18, 2018 9:41 am

74superTN wrote: Also, this is in a Vanagon, so I can't reach the battery terminals.

Not sure what is available for your use in an AC-Vanagon, but the Bay style test sockets had 12 power in them and the watercooled Vanagon had an electrical junction box that could be opened to access power.