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SIV diagnostic advice ??

Discussion in '"Stock" Alpine' started by SIVAllan, Mar 24, 2009.

  1. Ron67Alpine

    Ron67Alpine Silver Level Sponsor

    Um, isn't the valve cover insulated from the motor, by the gasket? When grounding the plug, to determing spark, I usually use the frame or a good place on the motor.
  2. SIVAllan

    SIVAllan Donation Time

    Thanks - I'll try that in the morning.

    The valve cover does sit on a thick cork gasket but I has assumed it was grounded via the studs/washers/nuts fastening it to the block.

  3. puff4

    puff4 Diamond Level Sponsor

    Correct, it is very well grounded by the studs, nuts and washers.
  4. Ron67Alpine

    Ron67Alpine Silver Level Sponsor

    good point, I didn't think of the bolts grounding it. I had a hell of a problem figuring out a non spark issue, it turned out the insulator on the set of NEW points was no good, and was grounding.
  5. Bill Blue

    Bill Blue Platinum Level Sponsor

    Always be suspicious of new parts when a problem arises.

    I have installed more bad new parts than I care to remember. We tend to forget them as a problem and it drives us nuts. Some of my biggest issues when ironing out the Alpinto were due to a new condenser that was bad, a defective electronic ignition reluctor, a spark module that died after 100 miles and a defective narrow band oxygen sensor.

    Is that run of bad luck or what?

  6. SIVAllan

    SIVAllan Donation Time

    A positive note today!! :) :)

    Spent most of the day trying the old 25D distributor, and getting weak spark, and the new 45D distributor, and getting no spark.

    Looking through my impressive pile of debris, I found an old 45D and studied it.

    The old 45D (a modified distributor by Alden (sic)) had different points, and the difference proved to be the key to no-spark resolution.

    Where the points/condensor wires join on a 25D, they use a plastic "gasket" that keeps them from grounding.

    On the 45D, no such gasket. That end of things sticks out in the air with no plastic gasket above and below.

    My new 45d allowed a short to occur against the floor of the distributor.

    I took the old and new 45D's to the local parts house, and the salesman disowned the Holland 45D as it's part number is not in his book.

    But a mechanic from the attached MGB restoration shop happened by, pulled out his Buck Knife, and bent things into proper form, VOILA no short.

    So, once re-installed spark returned.

    Airpine finally cranked again!

    Still a few issues.:confused:

    1--engine turns over "hard." It spins freely, then sorta "freezes" but then spins and finally cranks.

    Low battery maybe?

    I put the battery on charge overnight just in case.

    That's ok, right? It's positive ground, but with the ignition off I just hooked + to + and - to - ... ??

    2--The coil gets hot. Almost too hot to handle without gloves.

    How hot is too hot ??

    Why so hot ??

    3--carbs idle very rough. Not a surprise as much as they have been tinkered with over the last few days.

    Is there a 'rule of thumb' for an initial setting?

    As in for example, turn the air/fuel screw all the way in, then turn 1 1/2 turns of the fuel/air screw out from "stop" ?

    If one turns that screw in the opposite direction, all the way out, then all the way out for the fuel/air screw has no stop, so going in 1 1/2 turns would introduce automatically error between the two carbs as the start point would differ slightly ...

    Same for the idle speed screw? Maybe those can be set initially all the way out, then turned in 1 1/2 as a beginning ??

    4--if the spark remains good, fuel pressure is good, any other thing comes to mind to check before another test drive in the afternoon ??

    If all goes well, the car is set to run 400 miles competitively Sat. A. M.

    Again, thank you!!!

  7. Alpine Bob

    Alpine Bob Donation Time

    Just think, as the old saying goes, "If it wasn't for BAD luck, you wouldn't have any luck at all" Quote "Is that run of bad luck or what?
  8. Nickodell

    Nickodell Donation Time

    One of the cheapest, easiest to use but most effective ways to check the health of the ignition system is the Gunson's Spark Tester.


    You just hook it up to a plug lead and hold the other end on the plug top, then keep opening the gap until the spark can no longer jump the test electrodes. It will let you know instantly what voltage is being pushed through. The scale shows both the gap at the electrodes, and the nominal voltage in Kv. It's made of plastic, so you won't do a world record high jump.

    Re. hard to turn over: One of the possible causes is an over-advanced static ignition timing, but you state that the vacuum gauge showed a steady 20. Over-advance would have the needle jumping around at 20-22.
  9. SIVAllan

    SIVAllan Donation Time

    That is one of the coolest tools I've ever seen.

    I'll look into obtaining one.

    I did get a Uni Sync tool today and tried to use it. It's probably best to use two of them in concert.

    As a result, the car now idles rough, and the vacuum gauge no longer reads steady 20.

    The vacuum gauge now on idle fluctutes from 10 up to abt 15 I guess as the Smiths gauge I'm using only has 10 and 20 indicated, with color zones to indicate "drive" and "idle" for example.

    The needle moved from the "idle" zone to the "drive" zone due to my tuning effort ...

    I'm at a loss, and guess it's time to open the carbs and see if debris is inside.

    The engine is hard to start, spins in an odd manner, normal then seizes up, then spins, eventually starts

    The battery charged overnight so it is presumed Ok and not the cause of the odd spin, seize, spin etc then start.

    Someone more knowledgeable and experienced will come by in the morning.

    Increasingly I believe it's time to open the carbs to see if any debris can be spotted.

    Thank you.

  10. Bill Blue

    Bill Blue Platinum Level Sponsor

    Allan, as a SWAG, you have set the carbs to lean and compensated by opening the throttles. Try richening each carb a 1/4 turn, see what happens. If I'm right, the idle speed will increase. If it does, lower the speed with the throttle plate adjustment and see how it runs.

    As for the funky starter action, I think Nick is correct about the timing being too fast.

  11. SIVAllan

    SIVAllan Donation Time


    I did the 1/4 turn, that seemed to help some.

    Now the idle continues to speed up, slow down, over and over, but the range on the vacuum gauge is better, no quite so low as before, and also a little higher going to the border line of the 'idle zone' on the Smiths gauge.

    I can loosen and turn the distributor, not hard to do anymore :) . The 45D does not have the vernier as on the 25D.

    So you and Nick are saying to turn it counter clockwise a little bit ?
  12. Bill Blue

    Bill Blue Platinum Level Sponsor

    Allan, the surging you describe is typical of a lean condition. Give them another 1/4 turn.

    As to the direction of dizzy movement, I don't know the specifics of the Alpine dizzy. Just move it in the direction the rotor moves. That will retard the spark.

  13. SIVAllan

    SIVAllan Donation Time

    Bill, thanks,

    I gave them another 1/4 turn, which did not change things much, but retarding the distributor caused some change.

    After loosening the clamp, then goosing the distributor a bit, then another tiny bit, the engine started better, and once started, surged much less.

    Now it idles in the gauge's "idle" zone, surging some but staying in the color zone for "idle."

    It idles very fast, so I'd think to back off on the idle control screws, 1/4 turn at a time...?


  14. Bill Blue

    Bill Blue Platinum Level Sponsor

    Yeah, that should work. Just don't make any radical changes and do the same to each one. Have you put the timing light on it? May trying pulling the vacuum line to the dizzy while its running, see what happens. Keep the line plugged, though. Where are you getting the vacuum for the dizzy?

  15. SIVAllan

    SIVAllan Donation Time

    Ok, I can put a timing light on it but have a little confusion on this :) .

    Is the goal to remain within the static timing range (6 -- 10 degrees BTDC) ??

    The distributor vacuum line runs to the first carb. It's a thick, sturdy replacement line that should be Ok. The factory line broke.


  16. Bill Blue

    Bill Blue Platinum Level Sponsor

    More or less.
    As you have discovered, excessive advance can cause erratic idle. Manifold vacuum to the dizzy can cause this, so we need to be sure that is not part of the problem. So lets do this: Set the advance in the 6-10 degree range, with engine running at tickover and the vacuum line unhooked and plugged. Then, hookup the vacuum line. The Zeniths have port vacuum so the timing should advance only a few degrees or perhaps none. If it advances 10 or more degrees, there is a problem. Rev the engine while watching the advance. At low to moderate speeds, the timing should dance around, more dependant upon throttle setting than rpm or engine vacuum.

    Just making sure everything is operating correctly.

  17. SIVAllan

    SIVAllan Donation Time

    Hi Bill,

    Sorry for the delay; the spring monsoons are blowing through...

    1--Set the advance in the 6-10 degree range, with engine running at tickover and the vacuum line unhooked and plugged.

    Done: (Distributor already was static set to 6--10 BTDC although I DID move it a little in the retard direction.) idle sped up to fast, but stayed steady; vacuum gauge went to 20 then just beyond, to upper edge of "idle zone" on gauge, held steady

    2--Then, hookup the vacuum line. The Zeniths have port vacuum so the timing should advance only a few degrees or perhaps none. If it advances 10 or more degrees, there is a problem.

    Done: idle went down; vacuum gauge stayed in "idle zone" but went down closer to 20 also began to surge a little while staying within the "idle" color zone

    Rev the engine while watching the advance. At low to moderate speeds, the timing should dance around, more dependant upon throttle setting than rpm or engine vacuum.

    Done: when I step on the gas, vacuum reading goes to almost zero, then as engine returns to idle, needle goes to upper end of the idle zone, then down a little bit back toward 20.

    Just making sure everything is operating correctly.

  18. RootesRacer

    RootesRacer Donation Time


    You shouldnt have vacuum on the advance port at idle.

    This says your throttle is opened into the progression circuit of your carb and the vacuum port orifices are unblocked by the throttle plate.

    Not sure if you are saying this, its worth a check if you havnt.
  19. SIVAllan

    SIVAllan Donation Time


    You guys are pushing the envelope :) -- my envelope that is :) but what a great way to learn more about the Sunbeam :) .

    I'm not sure if I understand this:

    "You shouldnt have vacuum on the advance port at idle."

    I'll guess that to mean the vacuum gauge should read zero at idle with the vacuum line between the distributor and front Zenith WIP removed ??

  20. RootesRacer

    RootesRacer Donation Time


    The ported vacuum on the carb is supposed to be closed off (throttle plate blocking the vacuum passage) when the throttles are in their idle position.

    Its supposed to give some vacuum to the vac advance unit as you just tip into the throttle, where you need some extra advance and knock is not very likely.

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