Distributor cap, small dia, brass post style.

[husker77]

So I am changing my 77 prestolite over to the 78-up duraspark, not really the tfi because I'm using msd box and mallory coil. Someone posted a pic of a small diameter cap with brass posts, I think it was on ifjsa so it's lost in cyberspace somewhere. I can't seem to find that style of cap I've checked summit, jegs, and orielly's websites so if someone knows where I can find one that would be great.

[Stuka]

Napa Gold is brass point last I bought one. The lower end one is aluminum terminal style.

[husker77]

napa online shows some are brass, but they are all female plug.

I always thought the male is better, is my thinking correct?

[Stuka]

napa online shoes some are brass, but they are all female plug.

I always thought the male is better, is my thinking correct?

They are, I have just not seen any small OEM style caps with the male plug.

[husker77]

I thought I seen one posted one time but maybe I'm wrong. Both napa and orielly's has a msd large ford cap/rotor in stock and I have a ford 460 distributor sitting in the shed for the adapter. Of course it is sitting next to the 460 that may or may not eventually go in my cherokee, I LOVE the ford 460 engine, except for the mileage.

[Stuka]

I thought I seen one posted one time but maybe I'm wrong. Both napa and orielly's has a msd large ford cap/rotor in stock and I have a ford 460 distributor sitting in the shed for the adapter. Of course it is sitting next to the 460 that may or may not eventually go in my cherokee, I LOVE the ford 460 engine, except for the mileage.

I am a big 460 fan myself. My father still has his old '77 F150 Trailer Special which came with a 460, which has a mild cam and some other doodads.

I say go for the big cap, there is not any downside to it.

[babywag]

You mean like this...?

[husker77]

Ya like that.

Some opinionize(I just made up that word) that the adapter and large cap does not fit as tight/well as a single piece cap. I can see the logic in that. I do like the look of the bigger cap.

[babywag]

http://m.summitracing.com/parts/smp-al482

I removed the 2 piece Ford cap and used this.
I don't like the way the 2 piece fits, or the amount of real estate they take up.

[Stuka]

http://m.summitracing.com/parts/smp-al482

I removed the 2 piece Ford cap and used this.
I don't like the way the 2 piece fits, or the amount of real estate they take up.

The large cap does take up more space, but it serves a purpose. With an aftermarket high voltage coil, you can get spark jumping between electrodes on the small cap.


Sent from my iPhone using Tapatalk

[Bill usn-1]

That was only an issue back when the auto industry was opening up the plug gaps to .060 +-.
The small caps work just fine.
For a V8 there are 45* actual (360/8=45) between each post. The large cap simply increased the physical space between the post.
The only time there is a real problem with arc over is when there is too wide of a plug gap and there are other ignition problems.

Note that the factories went back to smaller caps in later years and the ignition systems have gotten stronger.

So if you plug gaps are within reason and the wires and plugs are in good shape then there is no issue with the arc going anywhere other than where it should go.

Nothing wrong with the big cap ford and GM HEI, there's just no reason to spend money on it unless you really like the looks of it.

Ih-International also used the prestolite distr. So you can also find it listed for something like a 1980 IH scout w/345.
I have used the prestolite cap on the motorcraft distr to get the male terminals. Then used something like the 454 plug wires cause everything for a chevy is 1/2 price.

[husker77]

Thanks guys, now I need to decide which to use, I can see merit in both trains of thought on the large vs small cap.

I'm gonna order the msd to duraspark adapter today. I usually just get the universal plug wires and make them to length, I'm not quite right that way. Thought maybe I would go with some really expensive wires this time, usually I use the Taylor brand.

[babywag]

I've never had any issues w/ a small cap on a Ford or a Jeep.
I've wound some engine pretty high
too.

Even running an MSD w/ hotter coils.
I didn't notice any difference between them.

Just my opinion run either just buy quality parts. No cheap caps w/ aluminum innards and you'll be fine.

[husker77]

So I have a rebuilt dura spark distributor on it's way, I just had them order me one for a 78. They said they would take my prestolite for a core.

So is the distributor gear the same from my prestolite to the dura spark? I would try and look it up on summit or something but I think carrier pigeons are running my internet data right now. I assume I should swap the gears, correct?

[tgreese]

So I have a rebuilt dura spark distributor on it's way, I just had them order me one for a 78. They said they would take my prestolite for a core.

So is the distributor gear the same from my prestolite to the dura spark? I would try and look it up on summit or something but I think carrier pigeons are running my internet data right now. I assume I should swap the gears, correct?

Parts book says they are, Jeep PN 3208615. However, the reman '78 Duraspark I bought for my '75 CJ-6 304 I could not exchange them.

Likely your reman will not come with the indexing tab for the cap. I made one out of a little rectangle of 1/8" G10 board.

JMO - why bother with the small cap? There are way, way more parts options with the big cap, and the wire attachment is vastly better. I've used two sets of the Summit universal silicone wires, and been happy with them. The Jegs universal wires are said to be good too.

[husker77]

JMO - why bother with the small cap?

Some guys think that with the adapter ring and such they don't fit as tight and are not as good as a small cap.

I can see the argument both ways. I'm guessing real world on a jeep that would be lucky to see 5000 rpm without blowing up that it is kinda of a moo argument(you know an argument made by a cow, it doesn't really matter).

[whowey]

Now you guys have me completely confused...

You are running that small black cap with the brass terminals... with the dura spark distributor.. or even an MSD box/hot coil and not having issues??

Cause I sure would love to have that simple black cap and hotter barrel coil for a closer to stock look with the hotter spark. A big reason I haven't put the TFI stuff on is I can't get in placed anywhere that I like the looks of it.

[husker77]

I am not and probably wont be, I'm to lazy to order the smaller cap and I like the look of the bigger red cap.

I don't see why it would cause problems to be honest, it's not like we are running massive rpms, that is where I could see problems arising.

[Bill usn-1]

RPM isn't really the issue.
As mentioned earlier the arc over is normally a result of poor ignition and large plug gaps. Spark will always look for the most direct path to ground.
If there is more resistance to take the proper path to the plug you want it to go to then it will take a path of least resistance which is normally a terminal next to it or straight thru the rotor to the distr shaft.

Any size cap will work just fine if the plugs/wires are correct and you don't try to exceed the maximum timing.

The duraspark distr with the magnetic pickup is a very good setup. Combine it with the GM 4 pin HEI ignition module in place of the ford ignition box and then run the ford TFI coil or a good aftermarket coil if there really is such a thing nowadays, and you will have a very good ignition system.
No need for pertronics or MSD or most other add-ons.

Keep in mind that the distr adv is mechanical and vacuum so parts wear and the rebuilds are a generic timing curve. So some time spent mapping out your timing curve by taking mechanical adv timing readings every couple hundred rpm and then measuring the vacuum adv degrees will give you a better idea of what your actual curve is.
It is all tuneable for your engine.


There is a whole lot of stuff that just gets repeated over and over on the web until people just take it as truth without ever even verifying it for themselves.
Well...I'm a french model and just get a date with a hot blonde. We met on the internet so it must be true.
I recommend if want to know if something is correct, verify it yourself.

You don't need a large cap to have a good performing ignition.
The large cap does absolutely nothing for performance.
There's nothing wrong with running the large cap but there is no need to go buy one thinking it will fix a problem with your ignition.
HTH

[FSJunkie]

Pay attention to rotor phasing. As the vacuum advance does its thing, it changes otor phasing. Change it too much, and the rotor air gap can become too great and weaken the spark, or worse: jump to the wrong terminal.

I've seen a few remanufactured distributors with a CCW rotor in a CW distributor, otherwise phasing is usually OK unless the cap is not the right cap for the dizzy.