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spark plug wire resistanc


M3M3

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terminals...they're meant to supress radio interference. IIRC there were two different terminal styles--a lower resistance one for use with carbon core wires, and a higher resistance one for copper core wires.

Either shouldn't affect spark plug operation by themselves unless they're defective. I'd check the terminals themselves one by one for a high reading.

cheers

mike

'69 Nevada sunroof-Wolfgang-bought new
'73 Sahara sunroof-Ludwig-since '78
'91 Brillantrot 318is sunroof-Georg Friederich 
Fiat Topolini (Benito & Luigi), Renault 4CVs (Anatole, Lucky Pierre, Brigette) & Kermit, the Bugeye Sprite

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either of those wire sets should cause running problems

but use the 500 OHM set

if you suspect the wires causing your 'problem'

test them only when cooking hot - that's the time they

will show any problem in increased resistance, and measure with the

ends on the wires, and wiggle them while measuring

to locate any breaks

the wiring to the coil and distributor are more likely

your trouble area - dirty, weak, broken, old, brittle,

connection integrety

and of course your probably not having ignition problems

look to your fuel / air mixing devices

What Is Your Running Problem Anyway?

'86 R65 650cc #6128390 22,000m
'64 R27 250cc #383851 18,000m
'11 FORD Transit #T058971 28,000m "Truckette"
'13 500 ABARTH #DT600282 6,666m "TAZIO"

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thanks guys.

was having bad idle and no power when trying to accelerate.

engine was running very well in my 73, so i put it in my 73. (9.5 mahle's, schrick 292, headwork)

put newer dcoe 40's on it but moved all the jets/floats over to new carbs.

older dcoe's had several clogged parts, only one accel pump jet was working.

same dizzy, same coil, same pertronix.

advance looks good, but seems like mech advance is high. 4btdc at 900 rpm, 30btdc at 3k rpm.

put new spark plugs in an ran it for 10 miles. pulled plugs. 1, 3, 4 look new. #2 is black. almost looks like only #2 was working.

DSCN3605.jpg

2xM3

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will try the wire switching. all four wires tested to same resistance end to end (cold...). i actually pulled the #1 wire off the plug while engine was idling...no change in rpm. then pulled the #3 off too, no change in idle. pulled #4, very slight idle change for worse. engine almost idled with just the #2 connected.

2xM3

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Looks like #2 is rich/ not always firing...

Changing DCOE's is always a crapshoot- there are a lot of

setup things that can go wrong (simple is synch..) and a new

carb isn't always a working carb, I have discovered..

2000 ohms for a plug wire simply means that it's a 'resistance' wire-

noise suppression wires have some resistance somewhere, and one

place to do it is in the wire. If you have low ohm wires (front to back)

you don't get much radio reception.

However, it can add up- 2k in the wires, 5k in the rotor, 5k in the plugs,

alla sudden you start to get a misfire under heavy throttle.

Buy new wires. Good ones. Be done with it. As I've said before,

effing crapo sparkplug (and coil) wires have stranded me more than flat tires...

30 degrees total advance is very conservative, and should serve you well.

4 at idle is a bit... little. You might be able to advance 5 and get more power

without your idle going to pookers.

Lotsa variables...

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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changed plug wires to the higher resistance set that were on the engine when it was running in the other car...until i order new ones.

changed the dizzy back to one with tii advance and allison xr700.

reset idle advance up to 9 deg.

now idles perfectly at 900rpm and when doing timing the marks aren't jumping all over the place.

only odd thing is when adjusting the idle mixture, the #4 barrel mixture screw has no effect on idle.

will test drive tomorrow to see how it works under load.

thanks for pointers!

2xM3

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update...

rechecked compression 185 +/- 2 on all

reset timing to 11 btdc at idle

checked fuel pressure load and no load 2.8psi

resynched carbs and reset lean best idle mixture

check spark plug gap

set idle at 920rpm. (still idles great)

test drove.

crap. still have huge stumble/shudder when you step on it from 2200-3000rpm. eventually starts to accelerate, but you can take a nap waiting for redline to come up in any gear.

about ready to rebuilt the old crappy dcoe's (that somehow worked) and put them back on...

2xM3

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  • 1 month later...

update 2

rebuilt the old italian dcoe's and put them back on...

runs great! starts without any choke and pulls to 6k rpm happily.

i guess the engine just wanted it's old carbs back. despite having the same jets and floats (literally, the same..i moved them), the newer spanish bodies didn't make the engine happy.

one other change i made at same time was to swap stock engine mounts in for the urethane ones i had in there. engine moves a lot more now, but maybe the lower frequency motion is not airating the fuel in the carb bowls as much...or not.

2xM3

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newer Spanish bodies didn't make the engine happy

huh... I've seen some newer Spanish bodies that made me happy,

so maybe your engine just has bad taste?

Older Italian just doesn't have the same odds...

heh

t

"I learn best through painful, expensive experience, so I feel like I've gotten my money's worth." MattL

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Guest Anonymous
newer Spanish bodies didn't make the engine happy

huh... I've seen some newer Spanish bodies that made me happy, so maybe your engine just has bad taste? Older Italian just doesn't have the same odds... t

If Toby's answers frighten you then you should cease asking scary questions.

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