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Thread: C950 Distributor change.

  1. #1

    Default C950 Distributor change.

    Currently have a GM HEI distributor triggering the Commander 950. Because of some ignition module and pickup problems I'm having lately, I was wondering if anyone out there has swapped to a Hall-Effect style distributor like the Holley Sniper 565-300. It appears from my research that this swap should work, but I was wondering if anybody has ever attempted using this distributor or a similar style and had good luck with it. Thanks.

  2. #2

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    I don't know that I've ever heard of anyone having trouble with an HEI, large/small cap, and the C950. As long as you have all the setup numbers right for it, the HEI is super reliable. Why do you want to switch to a Hall-Effect when HEI is so readily available, and very affordable? Doing something other than a small block? The C950 manual, combined with forum info here and at ChevyTalk should help you get the HEI setup quickly. What kind of trouble are you having?

  3. #3
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    Connecticut
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    Default

    Quote Originally Posted by Bill C View Post
    I don't know that I've ever heard of anyone having trouble with an HEI, large/small cap, and the C950.
    Plenty of problems when not using a genuine GM HEI ignition module.

    Defective ignition modules - common problem with MSD 8366 distributors.
    Replace the ignition module with a genuine GM ignition module.
    (This same rationale applies to Ford TFI distributors too.)
    ‒ Ignition module for MSD 8366 Pro-Billet Distributors:
    GM 19179578
    ACDelco D1943A
    http://www.rockauto.com/dbphp/x,cata...CO_D1943A.html
    http://www.msextra.com/doc/ms1extra/...EI_modules.jpg
    ‒ I'd also verify the GM HEI module polarity is wired correctly:
    https://forums.holley.com/showthread...ity#post120395
    http://www.megamanual.com/ms2/GM_7pinHEI.htm
    ‒ Apply heat sink (thermal conductive) paste on the bottom of the module before installing it.
    Often times, dielectric grease is wrongly used and will lead to an overheated (failed) module.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  4. #4

    Default

    Thank you for the reply. I've been running my setup for a long time. Since 2004. The engine/tune is fine. I've driven my car tens of thousands of miles all around the midwest to shows and races. Its a '80 Camaro with a 406 small block Chevy that makes 360 HP at the wheels. The original module seemed to last forever and when it finally did give up it was a slow progression from the occasional stall up to extended crank no starts. The replacement module at that time also lasted, but not as long. Recently I've been going through modules left & right. Have tried GM and aftermarket. Added grounds. Voltage dropped ignition and signal circuits. Using paste in correct amounts. It's a small cap external coil distributor. Was just wondering if a change to a Hall-Effect type distributor might help with reliability. Thanks.

  5. #5
    Join Date
    Dec 2009
    Location
    Connecticut
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    26,785

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    Hall-Effect type sensors are the most reliable.

    The more robust Hall-Effect sensors are preferred because they're not susceptible to EMI/RFI interference/noise,
    and their digital square-wave signal strength is consistent, regardless of RPM (unlike the VR magnetic sine-wave).
    Also, the VR magnetic pickup signal is weaker at cranking speeds.

    Hall-Effect: 3-wire, square wave signal (digital), pulse generation
    VR Magnetic: 2-wire, sine wave signal (inductive), voltage generation
    http://www.electronicproducts.com/El...g_for_you.aspx (Hall-Effect vs VR Magnetic)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS T/W 11R 205 heads, 232°-244° duration/.623" lift/114° LSA camshaft, 12:1 C/R, TFS R-Series FTI ported intake, BBK 80mm T/B, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, -6AN fuel system plumbing, Walbro 255 LPH pump, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, B&M Hammer shifter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 M/T Street Comp tires.

  6. #6

    Default

    So Hall-Effect is the way to go, which leads back to my original question of using the Sniper 565-300 distributor. If I choose to pick one up and give it a try, I should wire it as according to page 109, figure 84 of the Commander 950 manual correct? Thanks.

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