1974 VW Beetle Standard, no spark

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lw421
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Joined: Tue Apr 14, 2009 3:19 pm

1974 VW Beetle Standard, no spark

Post by lw421 » Tue Apr 14, 2009 3:48 pm

Hello, new to the forums, my names luke

Anyway, i just bought a 1974 Beetle from some old guy, and the body is in great shape (Absolutely zero rust, paid 3 grand). I drove the car home.

When i got home, me and my brothers spent around 30 minutes walking around looking at the car more in depth. Still looked great. Went to start it, and it wouldn't start.

So, i determined fuel is not the problem, and then i discovered i am getting zero spark at the plugs.

I have around 10 volts at terminal 15 of the coil, haynes manual says i need at least 9.6 volts, so i'm good at the coil. When i crank the car, i do get spark from the wire that goes from the coil to the distributor, but somewhere in the distributor i lose that spark.

I checked the distributor rotor, and it had alot of resistance, so i replaced it with a brand new bosch rotor. The spark plugs are also brand new (and yes, their gapped properly)

I have very little experience (zero) with a point type ignition system, so i am lost at this point.

Perhaps the pulse of spark from the coil is coming at the wrong time, when the rotor is not hitting one of the plug posts?

The wiring in the car is absolutely horrible, so that is a possibility too?

So if you could, please help me!

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david58
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Re: 1974 VW Beetle Standard, no spark

Post by david58 » Tue Apr 14, 2009 4:44 pm

lw421 wrote:
I have around 10 volts at terminal 15 of the coil, haynes manual says i need at least 9.6 volts, so i'm good at the coil. When i crank the car, i do get spark from the wire that goes from the coil to the distributor, but somewhere in the distributor i lose that spark.

I checked the distributor rotor, and it had alot of resistance, so i replaced it with a brand new bosch rotor. The spark plugs are also brand new (and yes, their gapped properly)

I have very little experience (zero) with a point type ignition system, so i am lost at this point.

Perhaps the pulse of spark from the coil is coming at the wrong time, when the rotor is not hitting one of the plug posts?

The wiring in the car is absolutely horrible, so that is a possibility too?

So if you could, please help me!
lw421 Welcome tothe STF.
How much is the spark able to jump? It should jump 3/8 of a inch to a ground. If it is the points condenser and coil are doing their job.
What does the button in the center of the cap look like? Since you replaced to rotor the button is the most likely suspect.

lw421
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Joined: Tue Apr 14, 2009 3:19 pm

Post by lw421 » Tue Apr 14, 2009 4:55 pm

I'm not sure how much its sparking, but i'm pretty sure its no 3/8 inch.

I have brand new points and condenser, i just dont know how to install/ set them.

Within the next few days, i plan on ordering a new distributor cap and spark plug wires.

now that you said 3/8 inch, i'm really doubting my spark. lets say im only getting around 1/8 inch, what should be my next step?

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david58
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Post by david58 » Tue Apr 14, 2009 4:58 pm

Replace the points and condenser. Then recheck the spark.

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Speedy Jim
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Post by Speedy Jim » Tue Apr 14, 2009 6:11 pm


lw421
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Post by lw421 » Tue Apr 14, 2009 7:31 pm

thanks everybody!

Sadly, i wont be able to work on the car until next weekend, but when i do i will go through all this stuff and let you guys know. Thanks for the help, and hopefully i can get my bug running before ii start to tear her apart for the rewiring!

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MNAirHead
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Post by MNAirHead » Wed Apr 15, 2009 9:36 am

Please post back with your success/progress

lw421
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Post by lw421 » Wed Apr 29, 2009 4:54 pm

Got to look at the car last weekend. I found that on the points a little mountain had built up on one side and there was a big dip on the other one to match it. I pulled the points out and tried to put in new ones, but i cannot get the screw to catch. Is there any special techniques for installing points?

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Speedy Jim
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Post by Speedy Jim » Wed Apr 29, 2009 8:39 pm

It's just a fiddly job.
If you leave the points out, can you get just the screw started? IOW, are the threads OK?
A screw-holding screwdriver or magnetic blade may make life easier.

Jim

lw421
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Post by lw421 » Sun May 10, 2009 9:46 pm

IT LIVES!

So i decided rather than trying to find the problem, i would just preform a tune up on the engine and see if she runs. I finally got the points in after removing the decklid so that i could get to them better. I changed the condensor (i think thats what its called, the little can on the side of the distributor) and adjusted the points too. Then i tried to set the timing, but failed, so i decided to check the valves so that i could know for sure that the number one cylinder was on its compression stroke. While i had the covers off, why not adjust the valves, so i did that too. Then i set the timing statically with a 12v test light and changed the plugs.

Hop in the car, turn the switch and she fired right up. What an amazing feeling.

That was a good days work on saturday (got up around 10, fired it up at 9pm), so today i decided to finally rebuild my carburetor. After a good 3 or 4 hours of work i got it done, put it back on the car, and again it fired straight up.

Man do i love air cooled vws.

However, the throttle response is ow non existant, if i try to jump the throttle too quick it just dies. it will reach full RPM if i move it up slowly. Is that just the two adjustment screws on the side, or did i do something wrong while rebuilding the carb?

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baja5
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Post by baja5 » Sun May 10, 2009 10:01 pm

Sounds like you need to advance the timing.I never had good luck setting timing with test light.. Try running it up a bit and see if that helps.

lw421
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Post by lw421 » Sun May 10, 2009 10:24 pm

you know what, now that you mention it i think your right. i think i have it at tdc right now. how many degrees btdc should i go? I know my manual said 7.5 degrees for a 1974, but my engine code starts with AH which my manual said was the 1971 California only code, so i was unsure.

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Speedy Jim
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Post by Speedy Jim » Mon May 11, 2009 6:12 am

It's not the engine code that determines; it's the distributor code or P/N.
Look for the # stamped on the side of the housing, then go here:
http://www.oldvolkshome.com/ignition.htm

SJ

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MNAirHead
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Post by MNAirHead » Mon May 11, 2009 1:10 pm

Glad the guys could help you - welcome to STF -

lw421
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Joined: Tue Apr 14, 2009 3:19 pm

Post by lw421 » Mon May 11, 2009 2:26 pm

yes, thank you all for the help.
I'm just 16, and i dont even have my license yet, so the experience and wisdom found on this site is integral to the success of many of the projects on my car. If it weren't for you guys, my family would still be making fun of my car not running.

I will work on the timing next weekend (the car stays at my dads house, i live with my mom) and hopefully i can get it worked out.

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