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Wed May 09, 2012 7:58 pm

Hello there.

Sweet '62 SC
1600 DP
H30/31
Bosch 010 timed to 32deg. max advance (now 30)

I just swapped for this carb / dist. combo from a 34-3 and DVDA with Pertronix for the combo above with points. I have the same 010 distributor in my bug, so I swapped them out and I'm having the exact same issue: A bad miss under acceleration. When it misses, my tach jumps all over the place so I'm guessing it's in the ignition.
Items checked:
Entire distributor (rebuilt)
All connections around distributor and coil
Plugs / wires / point gap, etc.

I haven't checked the coil, but it is pretty new. It is left over from the Pertronix swap, so this is still in there:

http://www2.cip1.com/ProductDetails.asp?ProductCode=ACC-C10-5842

I'm assuming this coil works fine with a stock points system?
Any ideas?

Thu May 10, 2012 3:01 am

You may not have the correct coil for a point ignition. Some have resistors, some don't. Dig up a stock one, or borrow one to see if it corrects the problem.

Wed Jun 06, 2012 4:45 pm

Well, I found an old beat up genuine Bosch blue coil at a swap meet. Tossed it in there and it seemed to do the trick. A little rough on acceleration in the 3-4k rpm range smooths out at steady speeds. But that's probably carb stuff.
Still kind of a mystery, though, since the Pertronix coil is rated at 3 Ohms, which is fine for points, right?

Thu Jun 14, 2012 8:59 am

Alright, I still can't figure this thing out.
With the replacement coil, the tach doesnt jump around, and it runs a little better, but...

-idles perfect
-can run it up in neutral and sounds fantastic.
-did a vacuum leak check with carb cleaner.

However, when I'm driving, lower RPMs are ok but once I hit around 2500 it starts to stumble and almost sounds like it's laying down on one cylinder. Fuel pressure is fine (in the 3psi range). 127 (or 127.5, I forget) main jet. Pulled the main jet, idle and power jets out and they look great.

Any idea on what to check next?

Thu Jun 14, 2012 9:12 am

Do you have a tach connected?

If so disconnect it and see if the miss is gone.

Thu Jun 14, 2012 10:57 am

Try measuring the resistance on the rotor. Had a faulty one one my bay window years ago. Replaced it and problem was fixed.

Thu Jun 14, 2012 1:43 pm

I just had a miss and it ended up being a spark plug (of course it was the last one I pulled). It is a good idea to replace the plugs/cap and rotor to be sure.

If there is anything connected to the coil besides the ignition components (ie tach and reverse lights) remove those connections and run without them and see what happens. I once had a tach wire chaffe through and ground to the chasis causing a problem.

Thu Jun 14, 2012 1:52 pm

what plug wires are you using? How old are they? What is your plug gap?

Thu Jun 14, 2012 4:21 pm

One thing I forgot to mention about this engine: I read in the rebuild notes that it has "low compression pistons". (I bought the engine used.) Would this affect jetting any?

I disconnected the tach on the way home, no change.

Plug wires are some performance ones, I forgot the brand. Bigger in diameter than stock, silicone, only a few years old. They still look fine.

The cap, rotor, points, and condenser are all new(ish) per Glenn.

I suppose I do need to pull the plugs, make sure they are clean and gapped correctly. Plug condition may have mattered less with the Pertronix system...

Thu Jun 14, 2012 4:59 pm

I would replace the plugs and gap them at the stock gap of .024" and when you do take each spark plug wire and check them with your multimeter on the OHM scale.

Thu Jun 14, 2012 5:06 pm

Sounds like a voltage drop issue to me. Could even be a bad ignition switch.
You could try running a hot wire to the battery and see if the problem goes away.

REMEMBER the car will not shut off with the key with this hooked up.

Also don't forget to leave the wire disconnected from the battery once your test is complete.

Fri Jun 15, 2012 3:43 pm

Will try jumping from the battery.
Plug report:

1,3,4 - beautiful and tan
2 - black and sooty, and the gap was a bit wide.

So I guess I have an issue with that cylinder. Checked valves again - they were fine.

Cleaned and gapped the plugs...still a bit rough at higher rpms, but better.

Fri Jun 15, 2012 4:24 pm

swap #1 and 2 plug wires at BOTH ends, see if the problem moves/stays.

Fri Jun 15, 2012 6:02 pm

[email protected] wrote: swap #1 and 2 plug wires at BOTH ends, see if the problem moves/stays.
Actually I might grab a plug wire off my bug.
I did measure that #2 plug wire, It was around 1 ohm.

Sat Jun 16, 2012 11:03 am

:) thing many missed was the comment of having the thicker silicone plug wires (they make more HP having the fancy colour) (tongue in cheek)

Decades ago had a customer with those NEW wires installed and still had a miss he wanted repaired. I did the normal Tune Up for him with a still constant miss at higher RPM. I replaced the wires with original Bosch and the miss was gone.

Customer did not like me charging for New wires since his were already New. Okay so with him watching I re installed his silicone wires and the miss returned...then changed back to the Bosch wires and the miss was gone. He shook his head and S*** canned the silicone wires.

People at times forget that it's not what is on the outside but whats on the inside is what counts.

Sat Jun 16, 2012 3:55 pm

while you are in the mood for looking at stuff,look very closely at the plug connectors ,i am finding a lot lately that just breakdown under load,if you look closely you can sometimes see very thin carbon tracks,either way check or replace ,there cheap

Sat Jun 16, 2012 11:58 pm

Funny people are all over the plug wires...
Yeah, yeah, I went for the "performance" stuff a few years ago. Went totally stock on my recent bug engine. 99% sure that the plug wires are fine though...Pricey Pertronix jobbies.
Weird thing is that I drove this thing around a bunch today and the more I drove it, the better it ran. By the time I got home, it wasn't missing at all.

F'n Volkswagens...

Sun Jun 17, 2012 11:57 am

i was having this problem this week. turned out to be the coke. butterfly flap was closing. i should say for clarity that the choke on my car isnt wired.(6v car-12v choke element) might be something to check.

Mon Jun 18, 2012 4:04 pm

I will double check the choke. I have it adjusted pretty conservatively so that it opens up quickly.

News for today is I swapped out the #2 plug wire - no change.
Interestingly enough, the blue silicone wires on my SC look fantastic. No name on the wires at all. Pulled one off my bug to swap, which are Taylors, (thought they were Bosch) and the distributor end looks horrible...badly corroded. Ran fine on my bug, though.

The miss / general rough running goes away (or seems to get better) when the truck has been fully warmed up for a while, like in stop-and-go city driving.
I don't know...I'll check the #2 plug again after a few more runs to work and back.

Mon Jun 18, 2012 4:16 pm

What kind of plugs are you using?