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Fri Jan 03, 2020 4:09 pm

Hoping someone can answer this question my VW Thing (1776 dual Kadrons, alternator conversion) is experiencing major hesitation on acceleration. In the midst of trying to trouble shoot I checked voltage at coil with ignition on 12.5 volts with condensor wire disconnected, 11.4-7 with condensor wire connected-is this normal? Also when trying to measure voltage at coil with car running the reading is all over the map-literally the #'s make no sense. When I try to check dwell again #'s jumping all over the place don't make sense. I can check battery voltage just fine with car running (high 14's) Thank you.

Fri Jan 03, 2020 4:56 pm

Sounds like it needs new points and condenser. If you measure the voltage to the coil on the high side to ground it should not jump around. However if you measure voltage across the coil primary it does jump or from the points wire side of the coil to ground it jumps around. A worn out distributor will have some side play in the shaft and the timing and dwell will jump around 5-10 degrees.
You should have 14 Volts at the Alternator with the engine running and typically a good ignition (Measured on the 15 wire at the coil) will run 1 maybe 2 volts less than the Alternator is putting out.
Voltages measured to ground!

Fri Jan 03, 2020 5:23 pm

Thank you for your reply-points and condenser are new-and there is no play in shaft of distributor-however there is play in breaker points mounting plate you can push down on one side and it causes the other side to move upward. Yes measured voltage to #15 and ground. I'm baffled about why my #'s are jumping around.

Fri Jan 03, 2020 5:44 pm

Yeah, It could be anything maybe a bad meter lead or something. Lag on take-off is common on 1600 engines however not so much with dual carbs but maybe the accelerator pumps are not working. I can hear mine with the engine stopped if i Listen with a hose to the carb. Double check your timing. I keep a spare distributor in my car If you have one try it.

Fri Jan 03, 2020 6:53 pm

Yes I have had problems in the past with the accelerator discharge tubes plugging-but they are both good-tester is good also-I can test battery voltage just fine. Thank you! also I checked again and there is only a voltage drop at coil (motor not running) when points closed-which is probably normal.

Sat Jan 04, 2020 5:46 am

If the numbers are jumping around with one meter probe on the coil+ and the other meter lead to ground while the engine is running, I must assume you are using a digital meter. There is a voltage kick of around 30V or so on the ignition switch side of the coil every time the points open. Not nearly as high as the over 200V kick on the negative side of the coil when the points open, but it is still there for a brief period. An analogue meter will basically ignore those short duration pulses while a digital meter will often pick them up making the readout screwy. Fred

THINGONER wrote: Hoping someone can answer this question my VW Thing (1776 dual Kadrons, alternator conversion) is experiencing major hesitation on acceleration. In the midst of trying to trouble shoot I checked voltage at coil with ignition on 12.5 volts with condensor wire disconnected, 11.4-7 with condensor wire connected-is this normal? Also when trying to measure voltage at coil with car running the reading is all over the map-literally the #'s make no sense. When I try to check dwell again #'s jumping all over the place don't make sense. I can check battery voltage just fine with car running (high 14's) Thank you.

Sat Jan 04, 2020 8:54 am

Yes that's true it is a digital meter I did not know that-the dwell #'s are jumping around also-Thank you!

Sat Jan 04, 2020 9:13 am

Yes, use analog meter, and do not be surprised if voltage at plus (+) side of coil goes down to 11 volts (or maybe less) , remember the energy (voltage/amperage) has to flow from rear of car (battery/generator/alternator) forward to and through ignition switch and back to coil... The path will cause some resistance and voltage drop...

IF you think you have a voltage drop problem, hot wire coil direct from battery with something like a 14 gauge wire and see if it changes how engine runs...

Dale

Sat Jan 04, 2020 10:03 am

Ok I am going to do some more testing today if I have time-thank you for your response Dale.

Sat Jan 04, 2020 10:25 am

I see no one has asked, "What distributor are you running? And have you checked that it is advancing properly?"

Sat Jan 04, 2020 11:01 am

Dale M. wrote: Yes, use analog meter, and do not be surprised if voltage at plus (+) side of coil goes down to 11 volts (or maybe less) , remember the energy (voltage/amperage) has to flow from rear of car (battery/generator/alternator) forward to and through ignition switch and back to coil... The path will cause some resistance and voltage drop...

IF you think you have a voltage drop problem, hot wire coil direct from battery with something like a 14 gauge wire and see if it changes how engine runs...

Dale
Yes this is why I put a relay on my car.

Sat Jan 04, 2020 1:08 pm

Dan Ruddock wrote: Dale M. wrote: Yes, use analog meter, and do not be surprised if voltage at plus (+) side of coil goes down to 11 volts (or maybe less) , remember the energy (voltage/amperage) has to flow from rear of car (battery/generator/alternator) forward to and through ignition switch and back to coil... The path will cause some resistance and voltage drop...

IF you think you have a voltage drop problem, hot wire coil direct from battery with something like a 14 gauge wire and see if it changes how engine runs...

Dale
Yes this is why I put a relay on my car.

Was going to suggest that if test with hot wire helped...

Dale

Sat Jan 04, 2020 2:50 pm

Okay thanks guys-so I got the all over the map dwell sorted out it was my rotor-checked multiple times and it was definitely the cause. My distributor is a Mexican bosch 034-I am going to check the advance and the voltage to the coil while running a little later today-with wire from battery if still fluctuating. thanks again! -

Sat Jan 04, 2020 4:32 pm

UPDATE-So I got my dwell set steady at 50-I checked the advance on my distributor and I'm at 30 degrees at FULL throttle-with vac advance hooked up it does go beyond the 30 degrees-but I really have to rev the crud out of it-vac can does hold vacuum with tester hooked up. Voltage at coil is 14.4 volts I turned my tester up to the 200 volt setting so before I had it set at 20 volts and I think that was the cause of the crazy #'s. Took it for a cruise and there is still some hesitation at part throttle but much better.

Sat Jan 04, 2020 7:41 pm

Is it a SVDA or DVDA?

With and SVDA you are supposed to set the timing from 28-32 btdc with full advance with the vacuum can NOT hooked up. The reason is that the vacuum advance will only kick in under load.

With a DVDA timing should be set with both hoses connected at 5 atdc at idle.

Sat Jan 04, 2020 11:01 pm

SVDA 30 degrees full mechanical advance (vac can disconnected) and then checked to see how much further it was advancing with vac can hooked up. I did not know that it had to be under load to advance with vac can-thank you.

Sun Jan 05, 2020 2:24 am

Best way to see how much the vac you engine is pulling and how many degrees your can is advancing is to tee in a vac gauge and run it to the front passenger seat. You can get a fuel pressure/vac gauge for 20 dollars or so from your local parts store. Tee in a long vacuum line and run it up through the air vents and into the passenger compartment. Go for a drive and see how many hg your engine is pulling.

Then go back to the engine and set the timing at idle to something like 10 atdc so you have a baseline. Hook up a minivac pump with gauge and while at idle pump it to create a vacuum and see how many degrees the can is advancing past 10 degrees.

Hope that makes sense.

Sun Jan 05, 2020 8:29 am

ok-yes thats a great idea-I get it-thank you

Sun Jan 05, 2020 4:57 pm

It is interesting and a learning experience when driving with a vac gauge in the passenger compartment since you can see how throttle positions and load have an effect on your engine vacuum.

Mon Jan 06, 2020 3:42 pm

T'd in a vacuum gauge and drove around today-vacuum is real unsteady not a gradual build up-seems really inconsistent I can mash my foot to the floor and it will stay at 0 then jump up at some point- sometimes response takes a long time and then other times I can just be cruising and it will show about 2 ish on the meter. I am getting some popping out of the exhaust at idle and my coil is super hot-lol the mystery continues I am thinking now maybe valves? A compression check showed 1&3 at 100 and 2&4 at 120.Well its a good thing I enjoy working on my beater I guess.