Surging and backfiring—-runs very rough

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Eric Decetis
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Surging and backfiring—-runs very rough

#1 Post by Eric Decetis »

Had my C car’s distributor rebuilt, engine timed and Weber carbs adjusted a week ago and car ran perfectly. Sat for a week and took it out yesterday; ran terribly. Surged and backfired dramatically. Ran very rough. Barely made it home after a few blocks. Your thoughts would be greatly appreciated as usual!

Eric

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Mike Wilson
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Re: Surging and backfiring—-runs very rough

#2 Post by Mike Wilson »

I'm pretty sure that the common consensus will be to start at square one with a full tune up. That way, you eliminate any variables, timing, etc. The problems you are experiencing could be electrical or fuel-related. It could be as simple as a loose coil wire or the distributor clamp not tight or...or...or...

Mike
Mike Wilson
Lomita, CA
'63 B coupe

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Eric Decetis
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Re: Surging and backfiring—-runs very rough

#3 Post by Eric Decetis »

Great, thanks Mike!

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Mike Wilson
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Re: Surging and backfiring—-runs very rough

#4 Post by Mike Wilson »

Keep us posted, Eric.

Mike
Mike Wilson
Lomita, CA
'63 B coupe

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Mervyn Hyde
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Re: Surging and backfiring—-runs very rough

#5 Post by Mervyn Hyde »

Eric, when the distributor was rebuilt, they probably fitted a shiny new condenser? If you still have the old one, just check that.
Merv
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1963 356B T6
1968 911 SWB

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Eric Decetis
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Re: Surging and backfiring—-runs very rough

#6 Post by Eric Decetis »

Thank you, Merv! We used to old condenser. Hmmmm. Maybe a new one is in order? Than you, again!

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Jon Schmid
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Re: Surging and backfiring—-runs very rough

#7 Post by Jon Schmid »

X2 on the condenser. If it's a Turkish made Bosch, X5. Don't ask me how I know.

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Eric Decetis
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Re: Surging and backfiring—-runs very rough

#8 Post by Eric Decetis »

Jon! I was checking the condenser brand (it’s German) and I noticed that the condenser bracket was loose at the set screw. Very loose. I snugged it up very tight and the car runs fine! Could it have been something as simple as that???? Big thanks to you!

Eric

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Mike Wilson
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Re: Surging and backfiring—-runs very rough

#9 Post by Mike Wilson »

Success! [the sound of hands clapping!]

Mikr
Mike Wilson
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Eric Decetis
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Re: Surging and backfiring—-runs very rough

#10 Post by Eric Decetis »

Yes indeed, Mike! Thank you VERY much!!!!

Eric

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Jon Schmid
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Re: Surging and backfiring—-runs very rough

#11 Post by Jon Schmid »

Eric, the blind squirrel (me) apparently found the acorn. All I know is that a lot of engine running issues seem to go back to cr@p Turkish made Bosch condensers. If this was just a loosely mounted German made unit, then I'm glad you checked it. I hope you fixed your problem for good, and you're most welcome.

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Eric Decetis
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Re: Surging and backfiring—-runs very rough

#12 Post by Eric Decetis »

Thank you kindly, sir!
YOU were a great help.

Eric

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Mervyn Hyde
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Re: Surging and backfiring—-runs very rough

#13 Post by Mervyn Hyde »

Well done Eric. Keep that German condenser as long as it will work. They are the best. The symptoms your described did sound like a condenser issue.
Merv
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1968 911 SWB

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Eric Decetis
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Re: Surging and backfiring—-runs very rough

#14 Post by Eric Decetis »

Thank you very much, Merv! I really appreciate your input!

Eric

Mike Horton
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Re: Surging and backfiring—-runs very rough

#15 Post by Mike Horton »

Jon Schmid wrote:Eric, the blind squirrel (me) apparently found the acorn. All I know is that a lot of engine running issues seem to go back to cr@p Turkish made Bosch condensers. If this was just a loosely mounted German made unit, then I'm glad you checked it. I hope you fixed your problem for good, and you're most welcome.
Tim Berardelli told us on the 912 Registry BBS forum, to find a U.S. made "Standard brand GB 125" condenser, to carry for a spare, and it will, like the original German ones, likely outlast your ownership of the car.

I found mine on Amazon. These come with the "horseshoe" shaped terminal, so if that hurts your conscience, swap it for the ring style terminal,

Heads up note: Be sure the condenser attaching screws (originally the shortest ones in the cast iron distributors) don't extend past the inner wall of the cast iron bowl, or aluminum, if you run an 031, or 061. I repaired one for a friend, in which the screw was too long, and it interfered with the outer return spring post, bending it. Adding washers under the screw heads, and straightening the posts, proved on the Sun machine, to have fixed it. Just sayin'...
Mike

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