Replaced the dual point with HEI

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Bewy, that text refers to the maximum current allowed by the HEI module. It isn't necessarily the same as the current the coil would run if allowed to dwell until it reaches steady state. However, if the module and coil are designed to work together, this may be the saturation current. See here for what saturation current actual is though... It's not the same as peak DC current in a steady state. In fact, it's significantly less.

https://www.vishay.com/docs/48155/_did-you-know_ihlp_saturation_vmn-ms7373.pdf

Also, even in a situation where the coil is badly matched to the module and is dwelling for 10 milliseconds at a 600 RPM idle - that's 25 milliseconds between sparks on a V8 for a lot less current than what you would see with the dwell on a standard Mopar electronic ignition. It's still limiting the current and getting around the need for a ballast resistor.
 

92b said:
Everyone looks like a genius standing next to me.
Click to expand...
Well, I almost made a comment about how stupid I am and Matt's probably "about normal" but that's not true. Just 30 seconds in with him and you know he's way intelligent. Me...not so much.
 
Mat,
Thanks for the link, but not sure how relevant it is. It talks about Ferrite & Powdered Iron cores & the curves are different for both of those. Ign coils have Laminated Iron cores.
 
id be inclined to stick with 40-45 thou on a small cap distributor, but that is based on me not noticing any improvement when i tried 45 and 50.... rather than misfire or phase-ing issues. You may find different. It is going to depend on CR and induction, cylinder pressure, fuel and air quality, exhaust efficiency, cam timing, all that stuff that dictates a fire or no fire... lean mixture or pollution of incoming charge with sucked-back-in exhaust gas etc

Also I like my current ignition leads... i don't necessarily want to turn their silicone core into scrambled egg in double quick time.

i approached putting back vacuum advance in potentially the wrong way but got good results

i messed with my mechanical curve until i thought i had it the best it would ever be

then wound down vacuum advance to the smallest amount (how many carb runners do i take a feed from...one only, now) and connected it to manifold vacuum...
pulls in lots at idle and a bit at just off idle

provided just enough to get me off the line a bit faster.

now when i lift off throttle at 70 mph it is no longer like i hit a wall of air resistance, the car just carries on, i must be burning something that i wasn't able to before.
From a driving point of view i made my car feel smaller and more agile....it could be described as "Nippy"

more work needed... but fuel economy improved and minor flat spot at 1800 rpm, a feature of weber's coming off transition into main circuit, gone. if id listened to the internet id be drilling more progression holes in my expensive carb bodies setting a "fat" idle mixture and drilling holes in throttle plates to compensate.... making matters way way worse with irreversible changes...

it is well worth putting in the effort on the vacuum advance front, makes part of your ignition curve demand/load controlled, as well as rpm controlled.

Dave
 
The main point of the link is to show that saturation current is not the same as the maximum current. In a typical coil, it's usually less - and there isn't much to gain by going over the saturation current.
 
Dave999 said:
id be inclined to stick with 40-45 thou on a small cap distributor, but that is based on me not noticing any improvement when i tried 45 and 50.... rather than misfire or phase-ing issues. You may find different. It is going to depend on CR and induction, cylinder pressure, fuel and air quality, exhaust efficiency, cam timing, all that stuff that dictates a fire or no fire... lean mixture or pollution of incoming charge with sucked-back-in exhaust gas etc
Click to expand...
273 with 10.5:1 .030 over egge piatons that calculated to 10.25:1 when i put it together 15 years ago.

I've already put the gap back to .050. At .060, I was having a miss after driving it awhile a couple days ago. No miss at .050.

Dave999 said:
Also I like my current ignition leads... i don't necessarily want to turn their silicone core into scrambled egg in double quick time.

i approached putting back vacuum advance in potentially the wrong way but got good results

i messed with my mechanical curve until i thought i had it the best it would ever be

then wound down vacuum advance to the smallest amount (how many carb runners do i take a feed from...one only, now) and connected it to manifold vacuum...
pulls in lots at idle and a bit at just off idle

provided just enough to get me off the line a bit faster.
Click to expand...
Planning to mess with dialing in the vacuum advance today. At the mopar meeting last night, a friend suggested this same thing. He converted the 383 in his wifes coronet and described basically the same thing.

Also said he had tried some weaker mechanical springs and ended up switching back to the originals that came with the distributor.

Dave999 said:
now when i lift off throttle at 70 mph it is no longer like i hit a wall of air resistance, the car just carries on, i must be burning something that i wasn't able to before.
From a driving point of view i made my car feel smaller and more agile....it could be described as "Nippy"

more work needed... but fuel economy improved and minor flat spot at 1800 rpm, a feature of weber's coming off transition into main circuit, gone. if id listened to the internet id be drilling more progression holes in my expensive carb bodies setting a "fat" idle mixture and drilling holes in throttle plates to compensate.... making matters way way worse with irreversible changes...

it is well worth putting in the effort on the vacuum advance front, makes part of your ignition curve demand/load controlled, as well as rpm controlled.

Dave
Click to expand...
Thank You Dave, I really appreciate the input!
 
Mine is still on mopar springs i think, i lost track both loop spring and round end spring still have a little bit of work to do
i just ended up with half of the advance in the distributor removed.

That let me do 15 BTDC initial 28 total mechanical
vacuum pulls it to 40+ at idle but its gone pretty quick...
mind with the equivalent of a 1.8 inch single barrel carb per cylinder i drive around on the minimum of throttle most of time, so that vacuum must be doing just a little bit a lot of the time.

dave
 
While it varies between engines, hooking up vac adv to a manifold vacuum source [ MVA ] can make a night & day difference. On one engine, I saw a 300 rpm increase in idle speed by just hooking up MVA. That means the engine made more hp, enough to raise rpm by 300, just from more timing at idle.

Scroll down to post #6:

www.hotrodders.com/forum/vacuum-advance-hooked-up-directly-manifold-bad-47495.html
 
Hei is a good ign. But I saw something about it not working well on distributors that have a tilt to them, like the chrysler big block. No idea why that could be, probably bs.
 
Bewy said:
While it varies between engines, hooking up vac adv to a manifold vacuum source [ MVA ] can make a night & day difference. On one engine, I saw a 300 rpm increase in idle speed by just hooking up MVA. That means the engine made more hp, enough to raise rpm by 300, just from more timing at idle.

Scroll down to post #6:

www.hotrodders.com/forum/vacuum-advance-hooked-up-directly-manifold-bad-47495.html
Click to expand...

The link is dead. For me anyway.
 
Great that your engine is running better. With all the changes, it is hard to know how much improvement the HEI part made. That it allows a larger spark gap always helps. It is also one less "knob" to adjust since dwell control is integral. The earliest electronic ignitions like ~1972 Mopar and even early after-market like Crane Cams XR700 still needed a ballast resistor (one more part to fail and more wiring) but still no dwell adjustment.

Even simpler is MPFI with crank-triggered ignition (~1987+) since no "knobs" to adjust. It is almost magical after rebuilding such engines when you just align the camshaft gears, connect the sensors and ECU and it fires up and runs perfectly, without having to adjust anything (nor can you) since all tuning is built into the computer, based on lab testing of the engine. If you modd'ed the engine (wilder camshaft) it may no longer be optimal. With aftermarket FI, you have many knobs to tweak (fuel and spark maps), which is very involved so auto-tuning as-you-drive software became common. Even with a factory ECU, some can hack the software to change it (tuners), but that requires expensive dyno time.
 
RustyRatRod said:
Well......sorta. But not the way he's thinkin. If it's the sho nuff GM style BIG cap distributor, the cap can interfere with some aftermarket tall valve covers.
Click to expand...
Okeh, sure. But "That ain't gonna fit" is a completely different thing than "It don't work well if the distributor is tilted".
 
slantsixdan said:
Okeh, sure. But "That ain't gonna fit" is a completely different thing than "It don't work well if the distributor is tilted".
Click to expand...
It's like if it's tilted, it's somehow out of line with the universe and ain't gonna work right. Big block Mopar, Cadillac, AMC, Buick...just of the top of my head. LOL
 
the really tall big-cap HEIs are for tilted use.... angles play a big part...

3,4,5 triangle
6 ,8 10 triangle

same triangle just one is bigger
6 is bigger than 3

if you catch my drift

Dave
 
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