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blue72beetle
Samba Member
Joined: April 23, 2008
Posts: 852
Location: Fort Wayne, IN
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 Posted: Sat Apr 27, 2024 8:14 pm Post subject: Suspected dead cylinder |
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1970 Ghia, 1600 single port.
I've been getting popping in the exhaust, and at idle the whole engine shakes bad. Can't find any exhaust leaks. I've replaced the plugs, wires, dist cap, rotor, points, condensor.
Compression numbers are all good 125-140 all 4 cylinders.
There's not many miles on these new plugs, but I'm guessing that #4 is not sparking?
_________________
-Andy-
-1970 Ghia-
-1971 Bus 1776 Microsquirt EFI- |
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modok
Samba Member
Joined: October 30, 2009
Posts: 26827
Location: Colorado Springs
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| Posted: Sat Apr 27, 2024 8:30 pm Post subject: Re: Suspected dead cylinder |
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You did find a clue but I think you are interpreting it wrong.
If #4 was not firing then how did it get carbon on it? Carbon is basically a result of burning.
Plugs 1 and 3 are too clean, like they aren't firing a lot of the time, which, on a Singleport might be normal depending how you drove it, or rather, wasn't driving it much....... but #2 should match #4
So honestly if I had to guess just from what we have here, I'd have to go with vac leak on the 1/2 side, maybe that would explain it.
Tho, more testing needed really.
Do a power balance test. Short out one plug wire at a time and see how much the rpm drops.
Check for vac leaks. |
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9513
Location: NOVA
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| Posted: Sun Apr 28, 2024 5:55 am Post subject: Re: Suspected dead cylinder |
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Oh..for petesakes. Install them plugs back on. Fire the motor and see which exhaust pipes are cold = them be your dead cylinders.
If your hand gets cooked, that be the HOT one. 
Run the motor and if you do find dead cylinders, figure out how. Plug wires bad? Coil bad? Points bad? Check your fuel source -
You already confirmed it is broken -w/ them good compressions.
Also -check your timing. Start it at ZERO degrees. Run the motor until HOT or operating temp. Then re-time to proper specs. Carb motors ~ 7 degrees BTDC. And all advance on timing to ~ 28 -32 degrees...by 2500 RPM.
Enjoy. |
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Don Jones
Samba Member
Joined: April 09, 2020
Posts: 200
Location: Makaha, Hawaii
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| Posted: Sun Apr 28, 2024 11:41 am Post subject: Re: Suspected dead cylinder |
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Get a temp gun (Amazon has them) and shoot the exhaust pipes and save from getting burned. You'll find which cylinder is the problem easily. A cheap valuable tool all acvw owners should have.
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nsracing
Samba Member
Joined: November 16, 2003
Posts: 9513
Location: NOVA
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| Posted: Sun Apr 28, 2024 1:20 pm Post subject: Re: Suspected dead cylinder |
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| I did not mean to render his hand useless and make his girlfriend unhappy. But I think the point is well understood. |
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blue72beetle
Samba Member
Joined: April 23, 2008
Posts: 852
Location: Fort Wayne, IN
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| Posted: Mon Apr 29, 2024 7:30 pm Post subject: Re: Suspected dead cylinder |
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| modok wrote: |
,
So honestly if I had to guess just from what we have here, I'd have to go with vac leak on the 1/2 side, maybe that would explain it.
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You may be on to something. I pulled the intake off and the nuts were not tight at all. The 1/2 side crush ring was not entirely crushed also.
The carb is getting a rebuild at volksbitz so when it gets back we'll see if that was it and go from there.
_________________
-Andy-
-1970 Ghia-
-1971 Bus 1776 Microsquirt EFI- |
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MuzzcoVW
Samba Member
Joined: February 21, 2018
Posts: 1503
Location: Westfield, MA.
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| Posted: Tue Apr 30, 2024 6:39 am Post subject: Re: Suspected dead cylinder |
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| It wouldn't happen to be a repro manifold would it? A friend has one on his single port... we had a hell of a time getting it to fit properly. It needed a little... adjustment. Out of the box it wouldn't seal for shit at the heads |
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blue72beetle
Samba Member
Joined: April 23, 2008
Posts: 852
Location: Fort Wayne, IN
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| Posted: Tue Apr 30, 2024 2:44 pm Post subject: Re: Suspected dead cylinder |
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No it's original. I recently resealed the exhaust and maybe I jostled the intake when trying to bolt the heat risers on.
_________________
-Andy-
-1970 Ghia-
-1971 Bus 1776 Microsquirt EFI- |
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MuzzcoVW
Samba Member
Joined: February 21, 2018
Posts: 1503
Location: Westfield, MA.
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| Posted: Tue Apr 30, 2024 3:00 pm Post subject: Re: Suspected dead cylinder |
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| Possible when you did the muffler if the bolts were loose. Be careful though! The torque spec is pretty minimal for those nuts |
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rugblaster
Samba Member
Joined: March 31, 2016
Posts: 1185
Location: San Angelo, Texas
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| Posted: Tue Apr 30, 2024 4:20 pm Post subject: Re: Suspected dead cylinder |
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Before temp guns, we used a squirt bottle and water. Shoot the tubes coming out of the head and you'll know the one or one's that aren't hitting.
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