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Alternative dizzy cams


mainer311

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Has anyone played around with the idle ignition timing and swapping to a different advance cam in an L series distributor?

 

The reason I ask is: on a stock smog R16 in a Roadster, there’s a 17.5 cam, idle timing is set to zero, and since total advance is twice the number stamped on the cam, you get 35 degrees max advance. When you recurve the dizzy and remove the smog stuff, timing is set to 15-16 BTDC, and you put a 7.5 cam in. Total advance ends up about the same, and the engine runs much better from the higher advance at idle.

 

Secondly, I have a dual points dizzy that I converted to single, and would like to modify to accept a #1741 Pertronix kit. The roadster cams are the right dimensions to accept the magnet ring in the Pertronix kit.

 

So what do people think, could I run a 7.5 Roadster cam in my dizzy and set idle timing a bit higher on my L16.

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We have discussed this before. Maybe search for distributor recurve.

 

Nissan Motorsports used to sell a short cam for the L distributor. I doubt they're available anymore, but it sounds like you have a selection to chose from anyway.

 

For a reliable street car I usually set the initial timing at around 12 and total timing around 32. Some say 35 total, but I find that to be pushing the limits.Of course, this is without vacuum advance, so if you're going o run vacuum, you need to take that into account.

 

Jeff at Advanced Distributors (distributorguy) may have something to say about this too.

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Yes what Stoffregen said.  7.5 is pretty extreme unless you;re running a DCOE setup.  You can also weld in the slot to set timing wherever you want it.  Measure the gap on your 17.5, divide by 17.5, and multiply by 8 or 10 or whatever amount of timing you want.  Then weld in the difference on the outside of the shorter slot.  Then good luck trying to get the rate of advance correct with the shortened curve so that you don't end up all-in too early.  It'll take a few tries to get it right.  

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17.5 is the stock R16 smog cam. The 7.5 is the recurve for the non-smog, running dual SU’s.

 

I think the stock L16 in the 521 is 10.5. Switching to the 7.5 is less of a change. Basically just want to advance idle timing a little more and then run the Pertronix. I may also have a lead on a matchbox, so, who knows.

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Right, but the dizzy that you used for the Pertronix started out as a single points dizzy, correct? Crash said the cam is too big or small for the magnet ring. Not worried about the Hall effect sensor itself, as extra mounting holes could be drilled and tapped in the breaker plate to mount it.

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For getting the advance rate right, I remove one spring and make sure the remaining spring has a touch of pre-load on it. Bend the tang holding the spring, if needed, to get the pre-load set.

 

You can use the Pertronix in either the single or dual point distributors.  Jeff doesn't like Pertronix, but they do make it easy. That's a whole 'nother topic.

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For getting the advance rate right, I remove one spring and make sure the remaining spring has a touch of pre-load on it. Bend the tang holding the spring, if needed, to get the pre-load set.

 

You can use the Pertronix in either the single or dual point distributors.  Jeff doesn't like Pertronix, but they do make it easy. That's a whole 'nother topic.

 

Have to mod dual points to use a pertronix as the holes don't line up, drop in when using a single points.  

 

Mainer you are right.  

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Have to mod dual points to use a pertronix as the holes don't line up, drop in when using a single points.  

 

Mainer you are right.  

Yes, you're correct, but they do fit. If you can't find a single point distributor, you can still use the Pertronix, it just takes a little work.

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 Single point whole dizzy? I've searched around and can't find anything concrete. A reman dizzy plus pertronix is going to get expensive, but certainly an option. 

 

I was initially asking about the roadster cam because I know the 1741 magnet ring will fit it no problem. 

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No results online.

Well non of this has anything to do with your original question. .

Any how look up a 72 521.... they list both for our truck.... but at that point just check out the 620 for an electronic dizzy and be done with it....

But I think you have to deal with the pedestal or the clamp or index the oil pump drive to make things bolt up..

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Easiest thing is to get the single point distributor, but anything from an auto parts store is going to be garbage and run terrible.  They clean, pack full of grease, and kick it out the door without testing.  99% of the ones I see aren't even repairable after the unspeakable harm they cause in the cleaning process.  

 

If you install a single point pertronix in a dual point distributor, you have to get the phasing right or it can fire between cap terminals and never run again.  I prefer points, even if they are hard to set or adjust.  Or find a member with a single point setup for sale.  That's what I run in the race truck at over 10,000 rpm.  They work.  

 

Run from anything labeled Cardone.  I have 2 280Z distributors on the shelf that are thrashed and unusable after their "rebuild."  

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Not sure what phasing you're talking about. I've already converted the dual points into single points and pulled out the retarding points control BS. 

 

My main reason for wanting to go EI is a hotter spark and wider plug gap. I'm currently running the single points on a 3 ohm coil with no ballast. I have a spare set in the glove box for that reason.

 

I'm getting a lot of misfiring when it's cold out, and I think it has something to do with the points/coil compatibility. Really just want to get the points out of there. There's someone selling a matchbox in the classifieds right now with the pedestal, but no response yet. 

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Well non of this has anything to do with your original question. .

Any how look up a 72 521.... they list both for our truck.... but at that point just check out the 620 for an electronic dizzy and be done with it....

But I think you have to deal with the pedestal or the clamp or index the oil pump drive to make things bolt up..

 

I've looked high and low. Can't find the single points anywhere.

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I've looked high and low. Can't find the single points anywhere.

 

Man I would never have thought they would be hard to come by.  Crash where did you get the single points dizzy you gave me from?  My 71 truck had dual points in it when I bought it which I assume were original.   Also not sure this has anything to do with it but when I put my pertronix in and gapped my plugs I had a hell of a time with my truck dying and running all over the place.  Changed a lot of shit since then but one thing I didn't do was gap my plugs and my truck seems to be running much better.  I guess I could gap them and see but why fuck with it when its been driving well? 

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Man I would never have thought they would be hard to come by. Crash where did you get the single points dizzy you gave me from? My 71 truck had dual points in it when I bought it which I assume were original. Also not sure this has anything to do with it but when I put my pertronix in and gapped my plugs I had a hell of a time with my truck dying and running all over the place. Changed a lot of shit since then but one thing I didn't do was gap my plugs and my truck seems to be running much better. I guess I could gap them and see but why fuck with it when its been driving well?

I got that dizzy from AutoZone... not sure why it's not listed now....

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