modified distributor rotor

[skata]

the red rotor is stock.
the gray rotor is from a ford.
the white rotor is stock with the ford tip.

i had a distributor laying around, so i decided to cut a hole in the cap and see the rotor tip in relation to the contacts inside the cap.
i noticed that the gap between the rotor tip and the contact points is about 3/16". i thought that was excessive.
i also noticed that on the inside of the distributor cap that the burn marks are always on one side of the contact tips, the advanced side.

so i put two and two together, actually one and one

i put the ford rotor tip on the stock rotor. i also moved it outward some to decrease the firing gap. i cut off the trailing end cause it's not needed.
when an engine is running, especially at idle and high rpm's, there is some more advance in the timing. and the spark comes before the rotor is aligned up with the contact tips. the more advance the more the rotor is off.

so i installed the rotor and i notice that the engine is more smooth and the idle is more consistent. i removed the rotor after driving the truck a little while and i noticed that i get a more even burn on the cap tips and the rotor.

i'd like to see someone else try this out and see if they notice an improvement. the donor rotor is from a ford taurus v6(early 90's).

 

[Guest]

I also have noticed this, and even talked to my local parts fellow about an aftermarket cap/rotor that had closer tolerances..... he laughed and said good luck. I do remember ages ago a buddies Buick V8 (in a 50 chebby) would often break a rotor as tolerances where then much closer.

I guess performance gave way to reliability.....

 

[SpoolingTurbo6]

Re

Re

Send me on I'll try it for a while :lol:

13447 99th ave N.
seminole fl.

 

[ghettosled]

looks like a msd rotor for the oddfire v6.

 

[decodave]

I've asked folks at MSD & some other ignition peeps & they all say that, that large gap increases spark energy . Seems weird, but they all say the same thing.

 

[skata]

I've asked folks at MSD & some other ignition peeps & they all say that, that large gap increases spark energy . Seems weird, but they all say the same thing.

i can see that making sense, but i was thinking that a smaller gap would give you less of a chance of misfiring or a no-spark condition, especially under high boost and timing. :-?
the reason i like this tip is the fact that the spark is not firing off the corner of the rotor when the ignition is advanced, which is almost always. i suppose you could put the ford tip on and leave the gap the same.
has anybody tried this out?

 

[4C FED]

:flash:

 

[93ty475]

Re: modified distributor rotor

i can see that making sense, but i was thinking that a smaller gap would give you less of a chance of misfiring or a no-spark condition, especially under high boost and timing. :-?
the reason i like this tip is the fact that the spark is not firing off the corner of the rotor when the ignition is advanced, which is almost always. i suppose you could put the ford tip on and leave the gap the same.
has anybody tried this out?

skata,

Did this end up working better for you after all? Kinda makes sense that it would work, but maybe what decodave says is true.....I like that you said that your idle straightened out....that's a good sign....do you still have the pics of the 3 rotors?

 

[skata]

Re: modified distributor rotor

ok, i fixed the pic. yes it is a little large.

yeah i still have the same rotor in my truck, and it still works good.
the biggest change was the smoothness of my idle.
someone else had mentioned to me that it made his idle more stable also.
i'd say try it, it's easy to do and cheap.

 

[93ty475]

Re: modified distributor rotor

thanks skata

 

[syclonekid43]

Re: modified distributor rotor

pic is a litle blurry to me. how did you mount the tip on the rotor?
and did you cut the tip on the chevy rotor before putting the ford one on there?

 

[truckins10]

Re: modified distributor rotor

Ive read about the larger gaps increasing firing KV also. But I think there is a better advantage to this mod. If you decrease the gap between the rotor and the cap, you dont waste all that energy trying to jump a useless gap. Id like to see some try and run a larger gap on the plugs with this mod and higher boost.

 

[skata]

Re: modified distributor rotor

pic is a litle blurry to me. how did you mount the tip on the rotor?
and did you cut the tip on the chevy rotor before putting the ford one on there?

no, i did not cut the chevy rotor tip. i placed the ford tip on top and a little further out to decrease the firing gap in the cap.
i used a little screw and nut to fasten the tip. do whatever works to hold that tip in place. there is no force on it. just remember heat is an issue.
you don't even need to use the ford rotor tip. just anything metal that will extend the chevy tip and provide an extended leg to it.

here are some more pics i had:


(tip looks crooked, it's just a shadow)

 

[syclonekid43]

Re: modified distributor rotor

cool deal. ill have to dig my syclone out of the back yard at the shop and try this. my truck sucks at idle. thanks for the pics

 

[Will_in_China]

Re: modified distributor rotor

This would have made for good dyno fodder at the nats...

 

[leroy]

Re: modified distributor rotor

I've asked folks at MSD & some other ignition peeps & they all say that, that large gap increases spark energy . Seems weird, but they all say the same thing.

I find that hard to believe. The larger gap adds unecessary resistance, lowering voltage to the plug.

I suppose it's possible that a larger gap somehow helps the coil's field collapse, but I can't imagine how.

Jim

 

[TYRODD]

Re: modified distributor rotor

Couldnt this be done with 2 stock rotors...adding another stock tip to the end of another stock rotor? Just to extend/make the rotor tip thicker, or does the design of the ford tip make the difference?

I may have a couple stock rotors around here...I'll go check it out

 

[skata]

Re: modified distributor rotor

Couldnt this be done with 2 stock rotors...adding another stock tip to the end of another stock rotor? Just to extend/make the rotor tip thicker, or does the design of the ford tip make the difference?

part of the idea is to make the rotor tip longer, but the other part is to make it wider and a little offset.
the reason being is that the rotor tip is not aligned up perfect with the contact tips inside the dist cap when the ignition fires, and the reason for this is because the timing is advanced.
the more advance the timing is = the more off centered(or mis-aligned) the rotor is in relation to the contact point in the cap when the ignition fires.
for example, take out your old rotor and you'll see that only one corner of the tip is burnt.

 

[leroy]

Re: modified distributor rotor

It's probably a good idea to check the timing after doing this mod. A wider, longer tip may affect timing slightly.

Jim

 

[skata]

Re: modified distributor rotor

It's probably a good idea to check the timing after doing this mod. A wider, longer tip may affect timing slightly.

Jim

no, doing this mod does not affect the timing. the timing is adjusted by rotating the distributor base. the magnetic points/ring under the rotor determines when the spark should occur.
if you do the rotor mod, nothing else needs to be done.
this mod just provides a better spark path when the ecm is really advancing the timing, ie idle and high rpm's.