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Help Needed. '68 Beetle Misfiring

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hulbyw Insano Dub Head

819 posts · joined Sep 2009 ·

#1027184
I have a beetle with a quite worn 1641 and standard carb. It has a 009 with Compufire, I made the mistake of giving it some love, such as filling it with BP ultimate, adjusting the valves and replacing the plugs and ever since it is misfiring under load. Starts ok but when revved or under load pops and farts.

To date I have changed the plugs again and new copper ignition leads. This fixed it for a day then it went back to worse popping and farting.

I have now put in a new rotor and dissie cap, new fuel filter and removed the carb and cleaned it and blew out the jets and orifices with compressed air.

It now goes a bit better but still popping and farting under load. Any suggestions to fix it would be really welcome
Cheers.......Wayne

bevoracing Officially Full-On Dubber

327 posts · joined Jan 2009 ·

#1027185
Wayne
I would re-do the valves. Sounds like they might be too tight when it gets hot. Give it a go, nothing to loose.
Good luck.
Tony
Country Buggy King & Link Pin Overhauls, Type 1 & 2 King Pins, General Machining.
http://forums.aussieveedubbers.com/viewtopic.php?tid=74138
My car is KO813

Bizarre Moderator The artist formerly known as blue74l

12,789 posts · joined Aug 2002 ·

#1027186
start from the beginning
Do a full tune up - valves, points, timing
Futue te ipsum!!!

splitbus Seriously Crusin Dubber

162 posts · joined Jan 2009 ·

#1027194
bevoracing wrote:Wayne
I would re-do the valves. Sounds like they might be too tight when it gets hot. Give it a go, nothing to loose.
Good luck.
Tony


Do a compression test on each cylinder, hopefully you haven't cracked the head changing the plugs

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Cheers, Mike
------------------------------------
| o*/o | 55 split screen
I don't have a bucket list, I have a f^%k it list a mile long

beetleboyjeff Custom Title Time!

1,790 posts · joined Feb 2009 ·

#1027201
I have had Compufires go before, and this is one of the ways they go. You could try putting points & a condenser in it and see if that helps - they are a lot cheaper than trying another Comufire (unless you have another one or can borrow one).
From your ole' mate Jeff

vduboy Insano Dub Head

702 posts · joined Oct 2012 ·

#1027213
Get rid of the high octane too. Unless the 1641 is a high comp motor you wont need more than 91. Steer clear of ethanol though. Would explain why the problem went away after new plugs.. Fouling up due to the fuel.
It will all be OK in the end, if it's not OK it's not the end!

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#1027227
Yea, dilute the 'good stuff' fuel with normal 91 and see if it gets better.
The old dak dak is low compression and higher octanes have been known to cause running issues cos high octane needs higher compression to burn properly.
madness is in the eye of the beholder 👍

vw54 Administrator Always Waiting 4 Friday

16,723 posts · joined Aug 2002 ·

#1027233
As per above start with the basics

Tappets, Timing, Plug gap etc

then look at filter and lines make sure you have flow
I read it on FACEBOOK so it must be true


http://forums.aussieveedubbers.com/viewtopic.php?tid=91278&page=1#pid848630


http://forums.aussieveedubbers.com/viewtopic.php?tid=63561&page=1#pid624099


http://forums.aussieveedubbers.com/viewtopic.php?tid=4832&page=1#pid452603


http://forums.aussieveedubbers.com/viewtopic.php?tid=60650&page=1#pid574409

hulbyw Insano Dub Head

819 posts · joined Sep 2009 ·

#1027319
Thanks guys. Doubt it is the fuel octane as I have been using Ultimate for some time. I have rechecked the valves and found the exhaust valve on #2 was tight again (same as last time). I re did all the valves but it made only a slight improvement. Too much other stuff happening right now so I will get back to it after Valla and let you guys know when I find the problem. Cheers and thanks again

psimitar Son of Jim - Creator of Good

2,506 posts · joined Jan 2009 ·

#1027322
If a valve clearance keeps going tight then it could mean the valve seat is sinking. Or as the exhaust valve the stem could be stretching and getting ready to break.

I can't think of any other reason for that to be happening.
madness is in the eye of the beholder 👍

68AutoBug Beetle Restorer - Experience over 138\% - YIKES --

11,654 posts · joined Aug 2002 ·

#1027325
Hi,
Have You checked the Hi riser heater pipe underneath the inlet manifold.
I have had a couple of them rust out which lets the manifold get very COLD if the outside temp is coolish.. it also allows the exhaust to leak...

Air Cooled VW engines don't like any leaks in the exhaust or inlet manifolds etc...
it looks like it maybe a cracked head...

I presume You have used a timing light on it...
I don't like 009's especially if they aren't genuine..
I don't believe using 98 octane should cause problems, E91 or E95 I wouldn't use.. [ethanol]
Did You use anti-seize or similar on the spark plugs??
I do on ALL alloy heads...
I did have a bad spark plug a couple of years ago... it tested Ok initially and it did go a few hundred KLMs before it started to play up.. the engine idled and drove Ok except on the highway/expressways etc over 90KMH.. it was like half spark on & off... but the engine didn't misfire etc..

Best of Luck

LEE


hulbyw wrote:I have a beetle with a quite worn 1641 and standard carb. It has a 009 with Compufire, I made the mistake of giving it some love, such as filling it with BP ultimate, adjusting the valves and replacing the plugs and ever since it is misfiring under load. Starts ok but when revved or under load pops and farts.

To date I have changed the plugs again and new copper ignition leads. This fixed it for a day then it went back to worse popping and farting.

I have now put in a new rotor and dissie cap, new fuel filter and removed the carb and cleaned it and blew out the jets and orifices with compressed air.

It now goes a bit better but still popping and farting under load. Any suggestions to fix it would be really welcome
Cheers.......Wayne
- Helping keep Air Cooled VWs on the road - location: SCONE in the Upper Hunter Valley - Northern NSW 320 kms NNW of SYDNEY---