Author Topic: Rotor phasing with digital timing control  (Read 3596 times)

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Pentroof

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Rotor phasing with digital timing control
« on: May 10, 2018, 06:58:23 AM »
Hi folks. I've got a fresh 390 together for my daughter's 1970 F100. I fired it off with a carb, but now I'll be changing it over to EFI with a Holley Sniper TBI unit.

I'm using a standard small cap with a Duraspark mag pickup and I'm thinking about using the Sniper to control timing. To do so, I'll need to lock out my mechanical advance and then align the rotor for optimum spark. I'm expecting 14-16 degrees at idle and maybe 36 degrees all in with my Edelbrock heads.

Cam is very mild (did I mention this is a truck?). Duration at .050" is 215/220 with a 113 lobe separation. Just offering this information to anyone who may want to suggest a curve profile for this combo in a daily driver truck. I don't yet know how the rate of timing is programmed, as the kit is arriving later today. However, they do have this helpful little video that gives you an overview.
https://m.youtube.com/watch?v=oBSiyeg4XCU
I'm assuming the ECU has a generic map that can be changed.

Anyway, my major question here is this: Do I have any options for an adjustable rotor for my Ford distributor? I refuse to use an MSD distributor (not looking for an argument here, that's just how it's going to be).
I have a couple ideas on making my own, but if an elegant solution already exists, I'll use it.

Thanks.

Holley uses a 45 degree reference point for their ECU and then maps the timing based on your
Jim

JamesonRacing

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Re: Rotor phasing with digital timing control
« Reply #1 on: May 10, 2018, 08:46:02 AM »
The Sniper timing control is rudementary, giving you only a start timing point, and a total timing/rpm point.  The Sniper draws a straight line between the two points and that's your timing curve.  The nice thing is that you can adjust total timing from inside the truck cab if needed.  The down side is that you don't see the benefit of integrating the timing into the fuel map.

I have used a duraspark for the same deal in another application and I simply removed the mechanical and vacuum advance parts, stuck a weld on the advance tabs to lock out any mechanical advance, then ran with it.  I have an old cap with a hole drilled over the #1 position so I can use a timing light to see where the rotor is in relation to the cap to confirm the rotor phasing.  You can adjust the phasing by altering the rotor/shaft position when you weld the parts to lock them out.
1966 Fairlane GT, Silver Blue/Black 496/C4 (9.93@133)
1966 Fairlane GT, Nightmist Blue/Black 465/TKO (11.41@122)
1966 Fairlane GTA Conv, Antique Bronze/Black, 418EFI/C6
1966 F250 C/S, Rangoon Red, 445/T19
1965 Falcon Futura 4-door, Turquoise, EF! Z2363/4R70W

cjshaker

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Re: Rotor phasing with digital timing control
« Reply #2 on: May 10, 2018, 10:58:02 AM »
I have an old cap with a hole drilled over the #1 position so I can use a timing light to see where the rotor is in relation to the cap to confirm the rotor phasing. 

That is a nifty idea!
Doug Smith


'69 R-code Mach 1, 427 MR, 2x4, Jerico, 4.30 Locker
'70 F-350 390
'55 Ford Customline 2dr
'37 Ford Coupe

Pentroof

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Re: Rotor phasing with digital timing control
« Reply #3 on: May 10, 2018, 02:50:32 PM »
Thanks for the replies. I want to adjust the rotor so the total sweep is centered with the cylinder post. I was planning on doing that with a hole in the cap and a timing light, as suggested. If I use a rotor with some marks on it, I could see how much I need to rotate it to get it centered in the sweep. I thought I would just cut two rotors and epoxy and pin an upper and lower back together (making up for the thickness of whatever blade I use to cut them).

If the timing curve isn't completely adjustable on the Sniper, perhaps I'm just as well off leaving the distributor as is and not let the ECU control timing?
Jim

JamesonRacing

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Re: Rotor phasing with digital timing control
« Reply #4 on: May 10, 2018, 03:01:14 PM »
The timing advance curve IS completely adjustable with the Sniper, and is worth the effort since you can adjust it from the control pad.  You get a straight advance to RPM slope, which is pretty much what any mechanical advance distributor will give you.  It just isn't as integrated as with the more fully featured FI systems, so it won't adjust due to load, throttle position, engine vacuum...., only RPM.
« Last Edit: May 10, 2018, 03:04:19 PM by JamesonRacing »
1966 Fairlane GT, Silver Blue/Black 496/C4 (9.93@133)
1966 Fairlane GT, Nightmist Blue/Black 465/TKO (11.41@122)
1966 Fairlane GTA Conv, Antique Bronze/Black, 418EFI/C6
1966 F250 C/S, Rangoon Red, 445/T19
1965 Falcon Futura 4-door, Turquoise, EF! Z2363/4R70W

Pentroof

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Re: Rotor phasing with digital timing control
« Reply #5 on: May 10, 2018, 03:24:34 PM »
OK, thanks for the clarification. You're right, of course, from a mechanical perspective.
I guess I'll put some time into reading the material that came with the kit tonight.
Jim

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66FAIRLANE

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Re: Rotor phasing with digital timing control
« Reply #7 on: May 10, 2018, 07:15:24 PM »
The timing advance curve IS completely adjustable with the Sniper, and is worth the effort since you can adjust it from the control pad.  You get a straight advance to RPM slope, which is pretty much what any mechanical advance distributor will give you.  It just isn't as integrated as with the more fully featured FI systems, so it won't adjust due to load, throttle position, engine vacuum...., only RPM.

I am pretty sure the timing table adjusts by RPM & MAP. Although I am not using it....yet.

machoneman

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Re: Rotor phasing with digital timing control
« Reply #8 on: May 10, 2018, 07:23:52 PM »
I'd be careful on the 'centering' of the tip to the post. In some cases, you want to lead the the tip a bit and NOT center it to the cap's post. Here's why: in high rpm engines (perhaps not in your case though) the spark starts to 'move' towards the following or trailing end of the post.

Easy to detect though. With that cut-open cap, start at idle and raise the rpms up to say 2K and then start snapping the throttle up to near top expected rpms. Watch where the spark jumps the gap, not where the rotor is. You may be a tad surprised at where the rotor's tip should be from idle to top rpms.   
Bob Maag

Pentroof

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Re: Rotor phasing with digital timing control
« Reply #9 on: May 10, 2018, 07:49:20 PM »
Jim

Pentroof

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Re: Rotor phasing with digital timing control
« Reply #10 on: May 10, 2018, 08:52:34 PM »
Looking into the timing control in the manual a bit more, there's good news:

"It is HIGHLY suggested that a timing map using the Sniper EFI PC Software is built for the particular engine the Sniper EFI is controlling timing on. The Timing map built using the handheld is very basic and each engine will perform much more optimally with a timing curve built for the specific engine combination."
Jim

JamesonRacing

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Re: Rotor phasing with digital timing control
« Reply #11 on: May 10, 2018, 10:26:35 PM »
I saw that as well tonight.  I helped a friend install his when they first came out and that didn't appear to be an option.  Now I'm intrigued. :)
1966 Fairlane GT, Silver Blue/Black 496/C4 (9.93@133)
1966 Fairlane GT, Nightmist Blue/Black 465/TKO (11.41@122)
1966 Fairlane GTA Conv, Antique Bronze/Black, 418EFI/C6
1966 F250 C/S, Rangoon Red, 445/T19
1965 Falcon Futura 4-door, Turquoise, EF! Z2363/4R70W

66FAIRLANE

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Re: Rotor phasing with digital timing control
« Reply #12 on: May 10, 2018, 10:50:27 PM »
When they first came out I don't believe the PC Software was available. Has been for a while now so you will need to plug a laptop into the Sniper or transfer the data by SD card from PC like I do. Oh..& if you want to plug a laptop in you have to buy a cable.
« Last Edit: May 10, 2018, 10:59:08 PM by 66FAIRLANE »

Pentroof

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Re: Rotor phasing with digital timing control
« Reply #13 on: May 17, 2018, 10:30:32 PM »
.
UPDATE

the Sniper install went very well. That re-grooving trick on the reluctor worked out well too. I used a small triangular file.

This little 390 is crazy responsive. After doing some more reading, I found out the Sniper doesn't really have secondaries...it has 4 primaries. By this I mean that all 4 butterflies open in unison, with no delay or progressive response built into the rear barrels.

This has caused some chatter amongst some users...and tire chirping too. Some have stated the Sniper is too abrupt for a street car and lacks driveability.  In response, Holley has released a new firmware version and a different link for the rear barrels. This gives an option of tuning the Sniper to have true secondaries. There is also an adjustable link and multiple slots that allows you to really fine tune exactly when the secondaries come on and at what rate.

I think I'm going to go this route, since my daughter will be the primary driver.
Jim

66FAIRLANE

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Re: Rotor phasing with digital timing control
« Reply #14 on: May 17, 2018, 10:43:00 PM »
Some have stated the Sniper is too abrupt for a street car and lacks driveability.

Really? Maybe my high stall softens it a bit. Responsive yes, but I don't see abrupt.