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Topic: Please help, bug's missing and I don't think it's firing on rear cylinders  (Read 5943 times)

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10
I just picked up a 4 cylinder 62 bug. It's running pretty rough and I don't think it's firing on the front 2 cylinders. I took all the wires off the coil to see if the engine changed and the plug to the left and right made no change, those wires go to the rear 2 cylinders, I choked the carbs to make sure it's getting gas with not much of any change in the engine. Any idea what might be going on and does anyone know any volkswagen mechanics in chattanooga that can take a look at this thing?

Offline Russ

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #1 on: September 19, 2012, 02:45:50 PM »
Have you done a compression test?

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #2 on: September 19, 2012, 02:56:40 PM »
Not yet, I've got to buy another compression tester.

Offline Russ

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #3 on: September 19, 2012, 03:22:28 PM »
Finding a mechanic that works on air-cooled cars is getting harder and harder. You can probably get a lot of good advice right here through our forums though.

Offline volksnick

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Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #4 on: September 19, 2012, 03:56:44 PM »
You said "carbs" which might be indicative of something other than stock, which could have been setup improperly and lead to troubles.

As a general rule, if its running rough, do a complete tune up: Adjust the valves (VERY IMPORTANT), set the timing, adjust the carb(s) and then it should run right. If it doesn't, you have some figuring to do with those carbs.

I posted some videos recently about how to adjust valves. Check them out in this thread.

http://www.volksfolks.org/forums/welcome-newcomers/nice-meeting-you-all/msg57637/#msg57637

You might be getting spark to those cylinders, but if their valves are too loose or too tight, it will either not let any fuel air in or not provide good enough compression to get any power. A compression test will tell you if your valves are staying open (low compression) or if they are closing and the rings are in good shape (100psi+ and all cylinders about equal).

Adjust the valves and report back!

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #5 on: September 19, 2012, 04:30:12 PM »
I bought a compression tester, came home and the threads are all too big to screw into the heads. What size threads are the spark plugs so I can go try to pick up an adapter?

Offline travisyoung

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #6 on: September 19, 2012, 04:45:21 PM »
Most have both threads on the tester,  I would check the firing order and the plugs for spark

Offline ASBug

  • Varnel, Ga
  • Joined: Jan 2008
  • Posts: 3032

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #7 on: September 19, 2012, 05:43:13 PM »
Where are you?
Engine=?
Carb or Carbs?
Is it a stock ish distributor firing system?
Inquiring minds want to know.
KC

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #8 on: September 19, 2012, 06:29:30 PM »
Please forgive me, i've never owned a volkswagen. All I know is it has 2 carbs, one on each side of the engine. Each carb has a seperate hole for that cylinder. I'm in chattanooga, east brainerd to be specific. I'm antagonized as I just cross threaded a head trying to screw the compression tester adapter into the head without removing the guard. The nut for the intake was in the way, took it off and still couldn't get it in, tried to put plug back in and realised it was cross threaded. I'll have to get a tap and try rethreading it. (bought a different compression tester that had a 12mm adapter)

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #9 on: September 19, 2012, 06:30:06 PM »
I don't know if it's a stock distributor, it looks stock to me? I dunno what engine other than a 4 cylinder.

If anyone on here that knows more about these engines than I do would be willing to stop by, i'd appreciate that.

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #10 on: September 19, 2012, 06:38:50 PM »
Maybe this will answer some questions?

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #11 on: September 19, 2012, 08:28:36 PM »
Compression test results...

All cylinders were 120-125 except #1. It was 90 but built up to 100 when I kept turning it over. I understand that's a pretty good difference, but it shouldn't make that much of a difference in the way it runs. I may try adjusting the valves tomorrow on that cylinder.

Offline volksnick

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Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #12 on: September 19, 2012, 09:04:07 PM »
Your engine is missing a lot of tins. It is an air cooled engine and the tins direct the cooling air over the cylinders to keep them from overheating. Without them, you are 100% guaranteed to overheat. I wouldn't try to warm it up to tune it without those tins on there.

You have an aftermarket carb setup which might only be good on a souped up motor. If its stock size cc you might be over carbed. I don't know about the firing order you currently have but if you pop the distributor cap off, you'll find a notch on the top rim of the metal part of the distributor. That's the firing position of #1. That is the front right cylinder (front is front of car). Going clockwise, next is #4- back left. Then #3- front left and finally #2 back right. 1-4-3-2.

Good luck!

Offline x_doug_x

  • Joined: Sep 2012
  • Posts: 10

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #13 on: September 19, 2012, 09:08:38 PM »
I pulled the left tin off so that I could get to the spark plug easier. I have it and will put it back on. The guy I got it from claimed it had aftermarket or worked heads, I dunno if this is accurate.

Offline attack chicken

  • Ooltewah
  • Joined: May 2007
  • Posts: 421

Re: Please help, bug's missing and I don't think it's firing on rear cylinders

« Reply #14 on: September 19, 2012, 11:38:12 PM »
Maybe this will answer some questions?


Well, looks like a pair of 40mm carbs, electric fuel pump, 009 distributor, MSD coil, the obligatory chrome tin..at least what's left of it, no tin to body gasket..not that it much matters because the tin that's there wouldn't seal against it, plastic spring loaded pushrod tubes, 12 volt conversion to a degree, header of some sort, no heat,firing order looks correct, looks to have a second wire off the - side of the coil(same pole as the green wire from the distributor) leads me to believe there is a tach, heads and push rod tubes look very clean, may have low miles...

That being said, those carbs would be a waste on a 1600 in more ways than 1. They are not cheap, I would guess its not a 1600, but that's just a guess.
(1) Did the car ever run well since you got it?
(2) if it has a tach does it jump around when it's running, jump from say 1500 to 2500 or 3000 and back to 1500?
(3) how long has the car been sitting/not driving on the road?
(4) if the answer to #1 is yes, when did it start running bad.

Also those intakes get in the way of the plugs as you have found out, you better remove the one on the side with the jacked up plug threads before trying to repair,you dont have to remove it all the way just move it over or you may end up damaging the head to the point of no return if it's not already there. Best to cut out access panels on both sides inside the fender so you can go straight to the plugs. Even then it will be very tight especially if it's running the large plug type(13/16 vs 5/8)
« Last Edit: September 19, 2012, 11:49:25 PM by attack chicken »

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