Duraspark Improvement

John Ha

Well-known member
Supporter 2022
Supporter 2023
I've had the Duraspark II setup on my 250 from the start and had been using an aftermarket "performance" coil that I'd bought long ago (I can only say that it's chrome and looks nice, and that it worked OK).

While rummaging through some of my stuff I found the coil from the 351 engine I bought (it had the Duraspark ignition).

On a whim I swapped the Duraspark coil into the 250 ignition system.

The car runs noticeably better - improved starting for sure and the "butt dyno" suggests that there's a bit more pep too.

Just thought I'd pass it along fyi.
 
If you have the DS11 & a MSD Box, the coil with the least primary resistance is going to perform better & with higher voltage. Such as the MSD Blaster 2 or 3.
MSD also has other higher performance coils that cost over $100.00, but only have .2 ohms resistance in the primary. 8251 & 8252 have different applications.
higpBpF.jpg
 
Congrats John.
plug gap?
Don't stop there, geta 'new car' outta da deal!
nice lill ign tune next?:

(o0OP, can't post bubba's nice lill 7 Step
but it has the sequence of operations)

Last: ck-in w/yer carb tune too...
 
chad":3jw7k2xw said:
Congrats John.
plug gap?
Don't stop there, geta 'new car' outta da deal!
nice lill ign tune next?:

(o0OP, can't post bubba's nice lill 7 Step
but it has the sequence of operations)

Last: ck-in w/yer carb tune too...
LOL

Baby steps, Chad. Baby steps. Some of us old guys, at least this one, are slow and need to deal with one thing at a time. :)

I used 040 for the spark plug gap. I could go a little wider, I think.

The car smells rich but not so much so that there's black smoke coming out of the tailpipe. I rebuilt the carb myself and I'm sure I did everything correctly but I will need to study/think on it some more while I address some of the other stuff that I need to do.

I could have messed something up when I was messing around trying to fix a fuel leak at the inlet. Fortunately, I have a spare carb (and lots of gaskets) I can pop on there if I decide to pull the carb that's on there now.
 
wsa111 said:
If you have the DS11 & a MSD Box, the coil with the least primary resistance is going to perform better & with higher voltage. Such as the MSD Blaster 2 or 3.
MSD also has other higher performance coils that cost over $100.00, but only have .4 ohms resistance in the primary. 8251 & 8252 have different applications.


Thanks for the input! I don't have an MSD box - can't see spending the money to put it on a car that's driven "grampa style" strictly on the street.

I was actually happy with the performance before I changed the coil but confess that the change is a pleasant surprise, and I especially love the fact that it didn't cost anything but a little time to swap the coils and do a little soldering to wire it in. :)
 
double post
:nono:
 
here it is.
Like urself (surely more so) I don't do anything fast. Decisions, spend, rest0mod...now w/older age, a touchada blues (robs my energy only), poverty...oh well...here's some joy. Found bub's post:
= = = = = = = = = = = = =
"...Distributor rotates CC fireing order is 153624
Autolite BF-82 plugs gapped at .034.
Valve lash setting is .016 hot for both intake and exhaust valves.
Basic Points setting gaped at .025 for best performance your looking for a Dwell setting of 39 Degrees.
Base timing is set to 4 Degrees BTDC for a Standard ( Stick) trans and 10 Degrees BTDC for a Automatic trans.
Idle RPM is 600 RPM for a Standard Trans and 525 RPM with an Auto Trans in Drive, parking brake set, AC if you have that is off
Fuel pressure is 4.5 PSI

To get most accurate tune up I always use of a tach / dwel meter especially if your Distribitor is still using the stock type points, and also a timing light. This is the procedure I have found works the best and quickly for me. Customized settings for your Pertronix.

A good tune up follows this order of work.
1. Set the plug gap to .045 with a Pertronix ignition.
2. Set the points basic setting to .025 after its runing set the Dwell Angel to factory spec of 39 degrees. This step is not needed with the Pertronix system. Skip this setting with the Pertronix
3. Now you need to set the timing to 12 degrees base timing vacuum line disconnected and plugged. You can also try more base timing to as much as 16 degrees but it if there is any hint of pinging when you try it then back off until it stops. Reinstall the vaccum line to the Distribitor.
4. With the engine warmed up good, set the valve lash to .016 on intakes and exhaust valves.
5. With engine warmed up good, Set the Idle mixture to its Lean Best Idle. ie set to highest idel RPM then turn the mixture screw in 1/4 turn to lean it.
6. Set the curb idle speed to 575 to 600 RPM if stand. Trans. Set idle RPM's to 500 to 525 RPM with an Auto trans in drive parking brake set, wheels chocked with block of wood, or you can have your daughter set on and hold the brake.
7. Repeat 5. & 6. To see if it improves anymore. When properly tuned these engines (warmed up) will restart without even touching the gas pedel.

You might also test your coils output with the volt / ohm meter as well as the plug wires and cap for their resistance readings that they are within spec.

Additionally while doing the tune up settings to the carb mixture and idle the engine needs everthing hooked up just as it will be operated! This includes having the Air Cleaner with a clean air filter installed and the PCV hooked up if your engine has one. If you want to use a Vaccum gauge then hook that up to the Intake Log below the Carb you would be looking for about 17 inches of vacuum at idle RPM..."
- - - - - - - - - - - - - - - - - -
all there 4 when U got the time...
BTW: U proved the 40 gap is better than the stock 34 gap/plugs (snappy new coil).Try 5 (or less) more?
 
Do what you want, but the MSD Box with a properly recurved DS11 & a MSD coil will improve the total operation of the engine.
Gap plugs .045"-.048" More power to you.
 
wsa111 & Chad - thank you both for your inputs. They are much appreciated!

Best, John
 
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