There is so much info out there, I would love to know all the tips and tricks I don't know.

Pretty much the same here. Sometimes you just want to kick yourself!

@@dazecars will this work with the Duraspark 335 series engine distributors - the 351m/400?

I believe so@@nova467spanker

​@@nova467spankerit does, very common among Fox guys where there's practically no room for the big cap and most popular intakes, and Lima 4's using this distributor modded in where the large cap physically isn't an option (that's going back some years to the turbo 4 days)

I have heard a lot of success stories after uploading this video

The gm hei module can be used too, just have to mount it on a heatsink. This is what I'm doing if my duraspark module ever fails. I have to look at how/when the hei module triggers, get the trigger leads wired in the correct orientation, I've forgotten.

While the GM module is more reliable than the Ford Duraspark box, the spark begins to taper above 3000 RPM so I am not a fan of it as a way to control spark in any sort of performance application. An MSD box is a much better option IMHO and eliminates the need for an OEM ignition box from any manufacturer.

@@dazecars I've heard this about the gm module before and suspect it's a rumor or reference to low quality replacement. Also, there are several configurations, so no telling what they saw. The hei module has always worked fine for my purposes (non-turbo) up to as much as 5,000 rpm WOT, I don't recall ever turning more than this.

I'm not saying that the HEI module will not work above 3000 RPM it does but it is a fact that all OEM HEI modules begin to taper the spark at 3000. Not sure why GM thought that was a good idea. If you use a Pertronix HEI module it will eliminate that taper and you will see even better performance at the upper RPM range.

That’s basically what I said when I found out

you are one of the few that knew this secret. So far only the second I have found.

Definitely information that a few have but as a whole not mainstream information. Thanks for commenting.

Thinking back on it; I strongly suspected the the distributor bodies being concerned had identical dimensions hence the aller cap/rotor

interesting

The theory that the bigger cap was to avoide crossfire is a logical theory but the closer you look it really dpesn't hold up. it's all theories and conjecture. Only the Ford engineers in the 70s really know. If the bigger cap was truly better high energy aftermarket systems like PerTronix and MSD would use this bigger cap, but they don’t. Their caps are no bigger than the international cap featured in this video. The prevailing "wisdom" as to why Ford made the switch was to avoid crossfire but if the duraspark suffered from crossfire there was some other factor like cheaper spark plug wires or other inferior materials they were compensating for as aftermarket systems don't have this problem and they run even hotter. Another theory is the bigger rotor allows for a longer spark duration for emissions. That is plausible but given the circumference os bigger the rotor is traveling faster so I not sure I agree with that one either. Regardless of why Ford did it, International ran this cap using all duraspark parts on almost everything V8 for 20 years so it clearly works and had it been problematic they would have done what was cheap and easy and switched to what Ford was already using.

Yes but those days they used carbon core wires for suppression and most had 8000 ohms per ft. Modern HIPO helical core wires usually have less than 200 ohms and suppress better. Wire resistance causes spark jumping in caps.

@@hotrodray6802 I ran the stock duraspark small cap female connection setup on a mild 302 with old-style "Mr Gasket" cut to fit 8mm resistance wires and never had a single problem with any ignition parts in 285K miles. I did pull the cap and dry-wipe it a few times as I checked on the rotor. I replaced the plugs at 50K thinking they needed it but I was wrong- they were like new. The next 235K miles were with the second set of plugs. The key is (other than wires) it was all OEM Ford, no aftermarket stuff. I've replaced tons of failed aftermarket stuff on these.

The MSD distributor for this application is horrible!

Ford did make the cap bigger to eliminate cross spark but not just because the Dura-Spark II system used higher voltage. My 76 f250 with a 390 in it had dura-spark II with a small female terminal cap. They switch to the larger cap in 77 I think on trucks I'm not sure when they switched on cars but they did it because they made the rotor tip about three times wider because they were trying to be able to deliver the spark through a wider curve. This necessitated a bigger cap to eliminate cross spark issues. Aftermarket companies such as MSD simply didn't worry about this and went back to a narrow terminal rotor, Ford themselves went back to this in the 1980s with the introduction of computer-controlled systems because they were able to more finely tuned the timing via the computer.

That is one advantage and a big reason I think Ford did it.

Glad to help

This IH cap & rotor should work great on a 351C 4V with a Tunnel Ram set up.

yes it should

Thanks, and I agree there are so many gems of wisdom that are getting lost. When we had forums as the main way help each other the info was accessible but now with social media being two easy tips like this get buried under pic of people standing by their car. It is really quite sad.

Yep yep Thanks:):):)

@@dazecars you can also use the DS-II distributor to run a GM HEI 4 pin module. Which allows use of E-core coil instead of the oil filled coil.

I use the MSD box

Yeah I like 100miles from the ocean and I enjoy watching safe bar crossing vids, so I'm hearin' ya lol

Glad you enjoyed it

glad I could help

Ford, International, and GM, really mixing it up 😂

I thought I was the only one that had a Duraspark distributor wired to a HEI module.

Oh the six banger falcon guys know gm trick ... I haven't yet but in the plan

@@jeff7.629 That's how mine is set up too

I did the same thing in a head to head comparison, and lost power, however it did work.

Glad to help

I will agree with that it is easier to install and route the wires.

For a cap it's bigger, but works better. There is problems with intake and multi carb systems. Just make sure it fits with the better cap. A better ignition is better than a inferior ignition. Easy fix for clearance issues. Better fix is to think about that before you pay good money for something that doesn't fit. I always liked the big cap. Have made a few point systems with the big cap. Quality cap, rotor, wires on some of the old dual point distributors make for easier adjustments to dwell with the thinner cap and collar. Old torker high rise no problem. Worked better for me. That car ran better with just that change. It had the old mechanical (spring advance distributor of a 289 hi-po) Always wonder how it would have done with a pick-up and box on the side. I also hooked up the higher volt coil from a dura spark II. Thing had a bit hop off the line with 4.56 gears. One of the many rides I remember with fondness. You just tip in with that mechanical advance it had wonderful throttle response. Plugs always had perfect brownish to little lean. I like the big cap.

you may like it but I am not convinced its "better". Its ugly, it flops around and If the bigger cap was truly better high energy aftermarket systems like PerTronix and MSD would use this bigger cap, but they don’t. Their caps are no bigger than the international cap featured in this video. International ran this cap using all duraspark parts on almost everything V8 for years and AMC, Jeep and Chrysler used the duraspark with the points cap so it clearly works and had crossfire or tracing been problematic they would have done what was cheap and easy and switched to the bigger cap Ford was already using.

@@dazecars- ive got several MSD distributors and they both came equipped from MSD with the big cap. Moroso and MSD made a dual input distributor for NASCAR so the car could be equipped with redundant ignition systems that consisted of two MSD boxes and two coils for reliability. If one system failed the driver flipped a switch to run the back up system. Both of those distributors used the big cap. If NASCAR preferred the big cap then I’m thinking the big cap makes for a better design. The MOROSO distributor was no joke and was very expensive.

Those are old school distributors or race distributors. Back in the late 90s MSD had a big cap almost identical to the Ford distributor cap but most of their modern ones are almost identical to the cap in this video. The video that drops this Saturday I hold a modern MSD distributor next to a Duraspark distributor with the International cap and the shape, size, and design of the cap is almost identical. The Nascar "proof" does not really prove anything because the applications are so completely different. The thing that has the biggest impact on crossfire is RPM. An engine that spends a lot of time above 5000 (nascar is almost double that) like a racing application is going to benefit from a bigger cap no argument at all and if you are racing you are not likely running a duraspark distributor to begin with. For a non race application how much time does that engine spend above 5000... little to none. The upcoming video rebuts all the "that cap will cause crossfire" comments I have gotten. Is crossfire possible with the international cap, yes given the correct circumstances ANY distributor can crossfire. Is it likely to crossfire in a street application with quality plug wires NO.

Slop is another issue with a 2 piece. A 1 piece fits with little to no play.

@@dazecars that reason alone with any of them from all replacement brands is why I try to avoid distributors wherever I can anymore these days, money permitting of course.. quality stepped up in recent years with better cheaper DIS conversions than we had just 5-6 years ago. Particularly like the cam sensor/oil pump drive unit with crank trigger on the main pulley approach when going port injected, or the simple crank trigger/oil drive when going distributorless & carb. No idea when the 'parts fiasco' will ever improve just beware of brand new whole distributors if eventual (probable) slop is a concern

That's why use use "aftermarket" caps and rotors which utilize brass terminals and blades. No "crusties".

@@johnjohnsn7633 Does that keep the hard starting moisture out in swampy climes...

@@MacPoop For that, try WD40. 😏

good information, thanks for sharing

Any time!

My pleasure, thanks for watching!

👍

Glad it was helpful!

Glad it was helpful!

My pleasure!!

happy to help, welcome to the channel

high praise, thank you so much. Glad you like it!

Yes it should , glad you like it. Please tell your friends 😁

There are three prevailing theories: crossfire inside the cap, crossfire outside the cap, and to increase spark duration for better emissions. While crossfire is a potential issue with any cap especialyas RPM goes up, if that was the reason it was to compensate for some cost saving thing like cheaper spark plug wires. Duraspark was used on tones of AMC, International, and even some Chrysler vehicles and non of them use a bigger cap, only Ford. Most use the female type points cap. So while crossfire is a possible reason I don't buy in as MSD and Pertronics distributors are hotter and use a cap of similar size. The "longer spark" theory seams to totally make sense when you look at the tip of the rotors and see the bigger rotor tip is almost twice as wide, but the terminals inside the bigger cap are smaller and the rotor tip for the bigger cap has to move faster because it has further to travel so I don't buy into that either. Ultimately this is all speculation however many view the crossfire theory as gospel. I would love to talk to a 70s Ford engineer to find out for sure. The one thing I believe firmly is for Ford to be the only manufacturer to do it, it was likely somehow a cost saving measure.

Glad I could help!

Glad to help

I run it the exact same way, MSD and duraspark as a trigger

It’s not just F250’s. My ‘77 F150 w/460 killed them too. It’s the heat!! Electronics hate heat! Ever see the goo melting onto the fender rail? Simple solution… air flow. I used (3) 1” pieces of ¼” SS brake tubing and (3) 1 ¾” machine screws to space the module away from the fender rail so that air flows behind it. No more dead modules in the Oklahoma summer. Note: I still keep a spare NIB behind the seat, JIC.

Truer words were never spoken, heat and electronics do not mix, especially electronics of 50 years ago but even todays electronics while they do better with heat it's still not a good combo.

I've been driving an 86 F250 351W with the same DS II module for 12 years, never had a problem with it?

the duraspark module works well as long as you are able to keep it cool

good information thanks

If you look closely you'll see those numbers stamped near the limiting slot. You'll also see a plastic tube on the arm to prevent metal-to-metal wear (which isn't really needed). Remove the tube for about a degree more movement. Back in the 'points' days there were several variations on this based on which exact engine it came on. This was the first "Ford trick" I learned waaaaay back then. The second was that some vacuum advances could be unscrewed and inside the spring was a phenolic limiting rod; by shortening it or blobbing JB weld to lengthen it your vacuum advance was also adjustable. Get anything you want from it at zero cost while the Chevy guys spend on advance kits 😁

good info, thanks

you're very welcome!

My Pleasure!

That is a theory but we really don’t know why ford did it exactly. Maybe to eliminate crossfire inside the cap, maybe outside, or maybe some other reason we don’t know. What I do know is it was likely to cut costs somewhere else like maybe spark plug wire quality. Aftermarket high voltage setups like MSD use a similar caps without issue and international used it for 20 years so it is likely not that big of a concern if using quality parts .

@@dazecars it was about 25 years ago when I rebuilt a 428 cobra jet for my truck. Back then it was a known upgrade, I can't say I've had problems either way, with the old set up for the new set up.

interestingly enough I am not finding many who have said it was a problem even with a hot ignition. @@karljay7473

Several other people have stated the same theory BUT international used this cap on Duraspark distributors for over 20 years and aftermarket distributor caps like MSD are also smaller. Your crossfire inside the cap statement doesn’t hold up. It’s more likely they were trying to prevent crossfire outside the cap. Something a good set of wires can accomplish. Thanks for the comment.

There have been quite a few people that have seen this vido and said, "you will have crossfire inside the cap, that is why Ford went bigger" The conventional wisdom that Ford went to a bigger cap to avoid crossfire inside the cap is a myth and like all good myths it is based in a sound logical concept but I just discovered proof that it is in fact a myth. Yes the terminals are further apart and logically that would indicate less unwanted spark jumping because the spark has further to go, BUT I went out to my garage and compared the smaller cap rotor to the bigger cap rotor and the bigger cap rotor has a much bigger tip to account for it moving faster. I took the distance between the cap contacts, subtracted the width of the corresponding rotor tip width and divided by 2. The number was THE SAME. That means inside the cap, from a spark point of view there is no difference. From this information it is obvious Ford made the change to the bigger cap fore some reason OTHER than crossfire inside the cap. Not to mention that if crossfire inside the cap was an issue there would be 20 years of Internationals sitting on the side of the road. imagizer.imageshack.com/img924/6218/wbhQQU.jpg

glad I could help

There is a lot of old school wisdom out there

It really is!

For me this distributor and an MSD box in place of the ford unit is the perfect combo

I agree

It is very interesting sll the different interchange out there.

Thanks for the sub!

interesting story thanks for the comment

My pleasure!

even new the two piece design is sloppy. I think thats why Ford made the bottom piece bolt down when they came out with TFI

glad I could help!!!

That is the number one complaint with the Ford module is they go bad. I eliminated my module all together and use the distributor to trigger my MSD box.

they work well

Glad it was helpful!

My pleasure

Thanks for the info

Ozone build up is eliminated by venting the cap and the bigger cap is vented so I will give you that. As to to spark skater that statement is a logical conclusion based on limited information. Lots of people keep saying that or something similar because it makes logical sense but that logic COMPLETELY IGNORES the number of Durasparks systems running this very cap or the female/points type cap from the factory. While crossfire/tracing is a potential issue with any cap especially as RPM goes up, if that was the reason, it was to compensate for some cost saving thing like cheaper spark plug wires or even more likely to compensate for high resistance wires that had an emissions benefit. Duraspark was used on tones of AMC, International, Jeep, and even some Chrysler vehicles and NONE of them use a bigger cap, only Ford. Most use the female type points cap. So while crossfire is a possible reason I don't buy it as MSD and Pertronics distributors are hotter and use a cap of similar size and design to the cap featured on this video. Ultimately this is ALL speculation however many view the crossfire theory as gospel. I have had a tone of people say they have been running this cap for years, I have had a tone of people say as you did "bigger is to avoid crossfire" but not one person said I tried the smaller cap, had crossfire and had to go back. If the bigger cap was truly better high energy aftermarket systems like PerTronix and MSD would use this bigger cap, but they don’t. Their caps are no bigger than the international cap featured in this video. Regardless of why Ford did it, International ran this cap using all duraspark parts on almost everything V8 for years and AMC, Jeep and Chrysler used the duraspark with the points cap so it clearly works and had crossfire or tracing been problematic they would have done what was cheap and easy and switched to the bigger cap Ford was already using.

The big cap works well.

glad it was helpful

Reading through the comments it seams as though this was very common knowledge in the 80s but then it some how was lost to the masses as an option.

Did you make the swap because smaller caps were actually suffering from crossfire at higher RPM or as preventative maintenance to avoid the potential problem?

@@dazecars I was having cross fire issues at the track, getting cross fire at starting about 5800 rpms... the Mushroom cap fixed that issue... The problem only seemed to show up when I changed from the 302 Boss motor to the 351 Street Boss. Not sure it was a cam to timing issue but the big cap fixed that and stayed in the 11.4 quarters at that :)

Thanks for the info. Your application (high RPM for sustained periods) is one area where the big cap makes a lot more sense.

it is for sure a good ignition system

Glad I could help

Glad it was helpful!

I agree points are a viable option.

No problem 👍

Glad it helped

@@dazecars again thanks as this was a stump in my project trying to retain the factory distributor timing which worked best compared to after market gm copys

my pleasure

good point. The only way to know for sure is to get it directly from the cam manufacturer. The concept that ALL roller cams need a steel gear is a myth. Most need a steel gear but not all.

Glad it was helpful!

exactly, that is why it is the "best kept secret" no one is asking the question. I only asked because I didn't have room for the bigger cap on my Frankenstein EFI project

They are a good distributor

so the duraspark and TFI use the same top cap but the adapter pice is different. The TFI mid piece screws down where as the duraspark piece clips down. The points setup is the same as the mid piece on the duraspark. In other words the points and duraspark are completely interchangeable but only the cap is interchangeable wit the TFI

My pleasure!

Thanks for sharing

I think it was more widely known in the 80s but the info has become more obscure.

My pleasure!

There are those that really like the HEI. I am not a fan but that is just my opinion

Glad to help

Glad to hear it… please tell your friends 😁

Glad I could help

No problem 👍

good to know

Thanks!! I was very pleased and surprised to find this option.

glad you liked it, thanks for the comment

Glad it was helpful!

Glad it was helpful!

Glad you like it!

My pleasure

Thanks for watching!

I think you can be a life long Ford guy and still not know because it's not that the information isn't out there it's that most are not asking the right question. People swap parts within the same make all the time across years, and if you knew Ford Duraspark was used on other make vehicles you would likely assume those vehicles used the Duraspark in its entirety and never even think to check if the cap or any other parts of the system were different. I also think this was more common information back when the Duraspark was in production but once they went TFI all the ins and outs of the Duraspark became less known.

I am running the exact same setup except for the stock distributor and a 6A box rather than 6AL. The MSD box is easily driven by the factory Ford distributor.

Its amazing how much room the smaller cap gives you

That is internet "wisdom". Lots of people keep saying that because it makes logical sense but that logic completely ignores the number of small cap distributors out there. The truth is we really don't know why Ford went with the bigger cap. There are three prevailing theories: crossfire inside the cap, crossfire outside the cap, and to increase spark duration for better emissions. While crossfire is a potential issue with any cap especially as RPM goes up, if that was the reason, it was to compensate for some cost saving thing like cheaper spark plug wires. Duraspark was used on tones of AMC, International, and even some Chrysler vehicles and none of them use a bigger cap, only Ford. Most use the female type points cap. So while crossfire is a possible reason I don't buy it as MSD and Pertronics distributors are hotter and use a cap of similar size. Like the crossfire theory the logic of the "longer spark" theory seams to totally make sense when you look at the tip of the rotors and see the bigger rotor tip is almost twice as wide, but the terminals inside the bigger cap are smaller and the rotor tip for the bigger cap has to move faster because it has further to travel so I don't buy into that either. Ultimately this is ALL speculation however many view the crossfire theory as gospel. I have had a tone of people say they have been running this cap for years, I have had a tone of people say as you did "bigger is to avoid crossfire" but not one person said I tried it, had crossfire and had to go back. I would love to talk to a 70s Ford engineer to find out for sure. The one thing I believe firmly is for Ford to be the only manufacturer to do it, it was likely somehow a cost saving measure. And for all the other manufactures to not do it crossfire is not the reason.

I have a video on putting a smaller cap on that as well kzfaq.info/get/bejne/nad0hL1p1rjMg2g.html

welcome to the party. thanks for watching!!

sounds interesting

@@dazecars just have to overcome rotational direction difference and job works a sweet treat.. killed two to make one a winner.. the joys of the pursuit to make horsepower more reliable..👍

@@dazecars last dyno sesh spark was above 80kv small cap and negligable cross firing so it was a win win..

a 460 duraspark distributor is identical to the Cleveland distributor and drops right in and works great with no fangling.

@@kblackav8or 460s are quite rare here in Australia..

when set up correctly and maintained points are an excellent ignition system. For me I was going to run an MSD box either way so it made a lot more sense to drive it with a magnetic pickup for accuracy.

It may have been the "best at one point but technology has improved. Lots of people have said that the bigger cap is to eliminate crossfire, Implying that if if you run the smaller cap you WILL have crossfire. While that may have been Fords purpose in theory it COMPLETELY IGNORES the number of Durasparks systems running this very cap or the female/points type cap from the factory. While crossfire/tracing is a potential issue with any cap especially as RPM goes up, if that was the problem, it was to compensate for some cost saving thing like cheaper spark plug wires. Duraspark was used on tones of AMC, International, Jeep, and even some Chrysler vehicles and NONE of them use a bigger cap, only Ford. Most use the female type points cap. So while crossfire is a possibility It's not likely. Look at MSD and Pertronics distributors they are hotter and use a cap of similar size and design to the cap featured on this video. Ultimately this is ALL speculation however many view the crossfire theory as gospel. I have had a tone of people say they have been running this cap for years, I have had a tone of people say as you did "bigger is to avoid crossfire" but not one person said I tried the smaller cap, had crossfire and had to go back. If the bigger cap was truly better high energy aftermarket systems like PerTronix and MSD would use this bigger cap or something of similar size, but they don’t. Their caps are no bigger than the international cap featured in this video. Regardless of why Ford did it, International ran this cap using all duraspark parts on almost everything V8 for years and AMC, Jeep and Chrysler used the duraspark with the points cap so it clearly works and had crossfire or tracing been problematic they would have done what was cheap and easy and switched to the bigger cap Ford was already using.

My pleasure!!

Yes but how much is the shipping. Rick auto has outstanding prices UNTIL you add the shipping. 😁

you are welcome

Glad you like it!

sounds interesting

@@dazecars thought you might like that idea since you frankensteined that one

👍

glad I could help

@@dazecars you're on VMF, yes?

yes from time to time, by no means daily

Yes but you probably went from the smaller female cap rather than the smaller male cap.

For me the bigger cap is a downgrade if for no other reason than it moves around. Gap will effect crossfire but that is not why MSD can get away with the smaller cap. in fact when running MSD parts like their ignition box opening up the gap is a step in the instructions. As to my thoughts on the big cap and crossfire I dropped a video on that very subject yesterday kzfaq.info/get/bejne/q6xko9qnvtydd6M.html