Prestolite vs holly distributor

Discussion in 'General IH Tech' started by Imperialdog, May 14, 2011.

  1. Imperialdog

    Imperialdog Farmall Cub

    I have a '78 Scout II with the 345. After having a mechanic replace a cracked valve ($$), it was recommended to me to replace the distributor. According to to the manual, I have a prestolite IDN-4000 series. When I ordered a new distributor from Scoutparts, they sent me a Holly. I installed that with an new pertronix ignitor II coded for the Holly and it would not start. I put back the points that came with it and it still will not start. Have I made a major "bonehead" move here? Non gold box. TIA
    Last edited: May 14, 2011
  2. orodos

    orodos Farmall Cub

    Any more info?
  3. Eric VanBuren

    Eric VanBuren Lives in an IH Dealership

    First mistake was ordering from Scoutparts. Your truck came with the Prestolie electronic IF you really needed a "new" distributor you could have gotten the correct one at your Local Napa for less than the Holley points unit and the Pertronix II.

    Have you checked to see if you have spark? Did you line everything up on #8 compression before removing the original distributor and line up the new one on #8 when you put it in?

    You should not try and run points on your rig w/o making some changes such as adding a ballast resistor and the resistor by-pass circuit. W/o the resistor you'll fry the points and possibly the coil. W/o the by-pass circuit you'll have trouble starting it particularly in colder weather.
  4. Will Marsh

    Will Marsh Moderator Staff Member Moderator

    First off, I'd just return the thing to Scoutparts if I could. You can buy either a Prestolite or Holley Points distributor from NAPA or O'Reilly for ~$100 exchange. I don't even want to guess what Scoutparts charged you for it. :(

    Personally I prefer the Holley Distributors. A couple of questions to get you a good answer.

    Did you get the timing right using #8 cylinder to time it? Are you getting any spark out of the distributor?

    Was your original Prestolite a points or electronic distributor?

    Did you put the Prestolite cap on the Holley with your old wires, or did you buy new wires to fit the Holley cap?


    Will Marsh
  5. Imperialdog

    Imperialdog Farmall Cub

    The original dist was electronic, stock, that big resin coated hockey puck, if my corroded brain cells serve. That failed around 1992, and I installed a pertonix ignitor then, which I never had to mess with since now. Is the Holly compatable with an engine that had a Prestolite, or do I need a Prestolite? I admit to being a chippie, electronics are confounding to me. It seems that I have no spark. I get turnover but no sign of ignition- it smells like gas after cranking for 20 or 30 seconds, no ignition at all. When I swapped everything I had it in neutral and just aligned the new one so the paddle slipped in just fine. The rotor seemed to be pointing at #1. At this point the rotor stops at random positions in the cycle, not at #1. I really want to know if the Holly will work with me or if I eff'ed up getting that. Thanks
    Last edited: May 15, 2011
  6. Eric VanBuren

    Eric VanBuren Lives in an IH Dealership

    Yes a Holley dist will work in the place of the Prestolite.
  7. RD Durham

    RD Durham High Wheeler

    All distributors used in International Harvester SV engines (305, 345 & 392) are interchangeable. What you may have to do is adjust your wiring. Points distributors used a resistance wire, so if you are adding a points distributor you need to check if you have a resistance wire or add an in line resistor, which is available for automobiles & can be purchased as most auto parts stores. If you are adding a different electronic distributor then adjust your wiring to accommodate a different electronic distributor. I don’t remember the wiring differences off the top of my head but they are shown in the shop manuals. I’m guessing but it sounds like you got your wiring mixed up when you swapped distributors. I’d go back and verify that you have the correct wires going the appropriate connections. If you got your wiring mixed up you may have also fried you Petronix unit.

    Check the wiring for your distributor, that it is properly set up & connected and if that is OK then verify that you have spark. Pull a plug wire and either use an old spark plug or a short bolt that will fit in the spark plug boot clamp. With a plug just lay it on the engine block where it will ground out and then crank the engine looking for a spark. You could also ground the plug with a wire from the plug body to the negative terminal of the battery. DO NOT directly ground out the spark plug body to the negative terminal. Car batteries produce hydrogen gas as part of the charge/discharge process and the spark could ignite this gas if it is present. If you use a small bolt just hold the free end of the bolt a short distance (approximately 1/8 inch) from the engine block and look for a spark. MAKE SURE that you are not in contact with the bolt in any way or you will get a good electric shock. Good luck.

    I also agree with the others about Scout Parts. How they manage to stay in business is beyond me. Their prices far exceed what you can readily get from most auto parts stores, and their prices for used items is ridiculous.
  8. scoutboy74

    scoutboy74 Y-Block King

    This sounds like a case of fixing something that wasn't broken...and then breaking it in the process. You had a cracked valve. That was repaired. Shouldn't that have been drive happy time? Why were you encouraged to replace the presto? Had it failed?
  9. 1975IH200

    1975IH200 High Wheeler

    Send the point dizzy back to where it came from.

    Go to NAPA,
    buy a Prestolite electronic distributor: NRD#4844822 or NRD#4844451,
    New cap: Eclin # AL162,
    New rotor: Eclin # AL163,
    New Plug wire set: Belden #700259,
    Eight (8) spark plugs: Autolite #ASP85 - gap to .035"

    Set timing off of #8 cylinder - which is the aft cylinder on the right bank (pasenger side). Initially set to 5 degrees BTDC (before top dead center)
    Timing makes are on the front of the engine, on the harmonic balancer, behind the crank pulley.

    IH SV-8 Engine Firing order is 1-8-4-3-6-5-7-2.

    Left bank is 1-3-5-7 from front to rear (driver side).
    Right bank is 2-4-6-8 from front to rear (passenger side).
    The distributor rotates clockwise, as viewed from the top.
  10. Imperialdog

    Imperialdog Farmall Cub

    The vacuum advance was not working, thats why I decided to replace the whole thing as an upgrade. By adding the ignitor II I was hoping to increase mileage. I replaced the stock electronic hockey puck in the dist in the 90's when it failed with an ignitor and never had to touch it since. With the engine rebuild, it seemed to make sense for just a couple hundred more to have a new ignition and save on gas for the next 10 years....
  11. RD Durham

    RD Durham High Wheeler

    You are not going to get much if any increase in fuel mileage out of an electronic ignition. You may see one or two MPG increase. It really depends on how well the point’s distributor was working when it was replaced. It really helps more with emissions than with any mileage increase. Electronic ignition gives a more consistent burn while running and helps a lot during cold weather. You also no longer have to do regular checks on your point’s gap so it’s a lot easier on your truck maintenance.
  12. Thomas

    Thomas Dreams of Cub Cadets

    ---Check to make sure the rotor is installed. When you pull the dizzy cap, pull the rotor and dust cover and snap a pic for us, then snap a pic of the wires coming off the dizzy. The caps work on either distributor. Male or female, no difference. The Prestolite body needs the dust cover for either cap to fit. The Holley's dust cover seats internally, so either will fit the Holley with or without a dust cover. Rotors are not interchangeable as they are keyed differently. They do however, have the same resistance, same reach, same height, etc., so again, the caps could have been switched at one point.

    ---You won't tell anything about TDC by turning the key on and off, there is no cycle of which it will stop at the beginning/end. As stated, clean around the #8 (... rear left bank when viewing from the engine) plug and pull it, pull the coil wire off, rotate the crank clockwise (only* ever clockwise) until the timing mark is on 0 and then use a screwdriver to see if the piston is at the top. If not, rotate the crank (clockwise only*) one more revolution and stop on 0. If you pass 0, go around two more times... remember, only* ever* rotate clockwise*.

    ---Now, pull the cap, and the rotor should* be pointing either forward or back. Most models point forward, some specs I have seen show the rear. Doesn't matter, but what does matter is that you have the vacuum advance pod half way between the thermostat housing and ear of the intake manifold and the rotor pointing at a tower. If not, pull the dizzy and set it back in so it is set up that way. TIP: When you lower the dizzy down into the block, the shaft will contact the oil pump about 3/16" before the drive gears start to mesh. drop the shaft into the oil pump and spin the rotor wherever you want it to point. Then seat the distributor. Where your rotor is pointing is #8 and to eliminate confusion, to train you to remember #8 #8 #8, I will just say to skip the 1-8-4-3-6-5-7-2 and start saying 8 - 4 - 3 - 6 - 5 - 7 - 2 - 1. We time on #8, firing order should start with #8. #8 and #1 aren't both at TDC at the same time, so #1 won't work so move it to the end and fughettaboudit.

    ---All IH SV8 distributors are interchangeable. What you find on a 266 will work on a 392, all in between and vice-versa. However, I have to stop you before you make a mistake... if in fact you are heading that way. The original ignition on a 1978 Scout II was a Holley External module. They didn't start using the Prestolite until `79... well, sometime after 09/1978 cause my 07/1978 (now StoneThrower) and my 09/1978 (gone) both were stock with a Holley.. If you're asking about a Holley points ignition then that's different. It will work, you just need a 1.4 Ohm resistor in the coil circuit or a coil with internal resistance... for points ignition.

    ---Now, if you're asking about the Holley Electronic Ignition, it is called a Holley External Ignition (AKA "Gold Box")... for a reason. The module is remotely mounted... external (on the firewall to the right and below the hood latch) rather than integrated like the Prestolite. No, you can't just install the Holley electronic/breakerless distributor and it will work. You'll need the module as well. So, that's $80-$100 (dizzy) + $60-$90 (module).

    ---The Holley is a much better design than the Prestolite. FWIU, the Prestolite's never held up well for GM even. The Holleys run much better when condensation is a factor, which it often is in regards to distributors. Neither electronic ignition will like the key being left ON when the engine is not running (same with most aftermarket ignitions) and no matter what ignition, you need to make sure there is a a solid ground. When it comes to the Holley "Gold Box", I would run a 16g wire from the battery (-) to the mounting screw that houses the ground strap. They're too pricey, too prone to burning up from misuse/abuse and a quality ground (steel is subpar compared to copper) will do nothing less than help protect your ignition.
  13. Eric VanBuren

    Eric VanBuren Lives in an IH Dealership

    The Prestolite is a superior ignition system to the Holley Gold box. They were both designed and built by Prestolite, use the same pulse induction technology and even share the exact same pickup and reluctor. The difference is the Prestolite figured out that they needed to do something about the problem of the transistor frying when the key is left on w/o the engine running and they fixed that problem before selling it under their own name. And it worked as there are lots of trucks still running their OE module over 30 years later. (you can easily spot a module made by Prestolite because it is fully potted to protect it from moisture with a gray conformal coating, the aftermarket units leave the printed circuit board bare) The only aftermarket ignition system that will fry if the key is left on w/o engine running is the Pertronix I. The only OE style system that key on engine not running problem wasn't fixed by the aftermarket is the Gold Box.

    Prestolite was never used by GM in automotive applications though you'll find them on marine engines. Chrysler and AMC used the heck out of Prestolite pieces and that is why if you go to Napa for a cap and rotor for a IH application Prestolite it will have a Chrysler prefix because that is the most common automotive application.
  14. nickl

    nickl Farmall Cub

    If the timing mark is at 0 and #8 isn't at the top, you have some serious problems. It will be at the top on every revolution since the timing mark is attached to the crank. Now one revolution will be the exhaust stroke and the next one will be the compression stroke. You want the piston to be at the top at the end of the compression stroke. Then make whatever wire the rotor is pointing at #8

  15. Thomas

    Thomas Dreams of Cub Cadets

    ---Did you get discouraged, step over to .org or where you minionated via PMs Imperialdog?

    ---I respectively disagree. I have ran both on systems with good grounds as well as sources and I will take the Holley over the Prestolite any day and FMO, not all* OEM IH/Prestolite modules came completely* "smothered" with epoxy.

    ---Sorry, I fell to the habits of others with "the screwdriver". What I always say is to pull the #8 plug, plug the hole with a wad of plastic shopping bag or similar, small enough to fit in the hole but large enough not to fall in, then bump the starter till you hear the audible "POP!" (won't happen unless exhaust valve is closed), then rotate the crank (clockwise only) past the 0 one time and stop on the 0 the next. The whole point was TDC vs TDE with cam timing as nickl explained. Crank can be at 0, but TDC requires both valves closed... and if on TDE, the exhaust valve will be open. Which is the loping sound heard in the exhaust long before the unburnt fuel blows the power valve with a big cough through the carb.

    ---I have got to figure out what is wrong with my eMail notifications for "threads to which I have replied"

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