BB Mark Jumping around

Discussion in '1947-1954' started by destryrideagain, Dec 1, 2010.

  1. destryrideagain

    destryrideagain Member

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    Today I set the points because my dwell was reading over 50 deg. I started with .016 feeler gauge which brought the dwell down to about 40 deg and idling rough, so I opened the point some more and finally got it at 30 deg and was running okay in ballpark manners. I hook up the timing light and tried setting it to the BB mark on the pointer and everytime I got it lined up it would jump up and down around the pointer and I could hear and feel the engine stumping then it perks back to the BB mark and idles good and then jumps around the needle again. I cleaned up all my spark plugs and gapped them .035 Anyone have a clue whats going on? Do I need to work on my points some more or take the dist. out and start from there?
     
  2. 51 HHR

    51 HHR Member

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    vac advance

    did you disconnect the vacuum advance?
     
  3. destryrideagain

    destryrideagain Member

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    Howdy, yes i did! from the carby side
     
  4. Bill Hanlon

    Bill Hanlon Member

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    30 degree dwell is appropriate for V8 points. I believe 6 cylinder is higher, but don't remember the value.

    I do know that higher dwell angle = smaller points gap.
     
  5. vwnate1

    vwnate1 Member

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    Proper Tune Up Procedure

    You _always_ need to begin with a valve adjust , then , remove the spark plugs and dist. rotor , set the cap aside and connect the dwell meter , crank the engine whilst observing the dwell , adjust the gap until it reads 33° dwell and tighten the screw , re-check the dwell and button it all back up and start the engine , set the idle speed to 700 RPM's or less and adjust the timing to ball on pointer ~ it should smooth out and maybe need final idle speed & mixture adjustments .

    As you can see , each thing you touch affects another thing so it's critical to do them all in the right order else you'll chase your tail forever , not fun .

    I hope this helps , remember : if you grab the dizzy shaft and it has more than a little side play , this will cause points bounce and erreatic running , this is why adjusting the dwell while cranking the engine is important ~ it compensates for upper dizzy bushing wear...

    I assume you've checked for a white or blue spark ? points are cleaned with alcohol of new , burnished with a points file (super fine) if used ? .

    Dot every 'i' and cross every 't' and you'll get it .
     
  6. destryrideagain

    destryrideagain Member

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    Okay Nate, Today I will adjust valves, my first time doing so! Hopefully grandpa can help ~ What is your preferred method of hooking up the dwell meter? I thought you shouldnt mess with the carb idle or anything until everything else is complete?
     
  7. destryrideagain

    destryrideagain Member

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    Have not checked for white or blue spark, I will need instruction on how to do this! I need to learn all this stuff somehow! Nate you have been great help along with everyone else here.
     
  8. vwnate1

    vwnate1 Member

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    Dwell / Tachometer & Valves , Carby Tweaks

    O.K. ~


    The Dwell Meter has two leads , one should be red , this is connected to the wire connecting the points to the coil , the other lead should be connected to the coil bracket or other place as close as possible to the coil/dizzy , at the very least to the engine proper , never the body nor battery .

    If your Dwell Meter is old like mine , get some red & black fingernail polish (cheap at the drugstore) and mark each lead the next time you have it correctly hooked up so you'll always know quickly in the future .

    If you look up older posts under ' valve adjustment ' , you'll find a Tech Article written by some old geezer who claims to have worked on a Stovebolt Engine once or twice :rolleyes: .

    It is best to adjust them when the engine is fully warmed up but for now , just do them , taking your time to ensure there are proper gaps on all 12 valves as troubles come from tight valves , *never* from loose ones . if you cannot hear them click @ idle , they're TOO TIGHT ! .

    (" A noisy valve is a happy valve ! ")

    You are correct , the carby's adjustments are the very last part of any tune up rather than the first thing to touch like most folks do .

    " Carburator " is a French word , it means : LEAVE IT ALONE ! :p .

    Only touch the idle speed adjustment on the carby's operating lever , to slow the idle speed down to 1,000 RPM's or less when checking & adjusting the ignition timing ~ if the engine doesn't shake , you can simply un plug one spark plug wire and this will slow it way down , instead of touching the carby , if the engine doesn't stall out , you're good to go set the timing .

    There should be NO VACUUM at the vacuum port @ idle ~ if there is , either you're using the wrong port or the carby has a problem , maybe a vacuum leak between the intake manifold & cylinder head caused the DPO/DPM to adjust the idle speed way too high so it's pulling vacuum when it shouldn't .
    (common)

    Go buy a cheapo fuel pump tester / vacuum gauge from Harbor Freight , or your FLAPS , I got mine from the ' junk box ' at a pawn shop , they had no idea what it was for and the ruber hose rotted away , a good old gauge that's still in Commercial Service 35 years later and it was old when I bought it for $1....

    I'll address how to use it later , after you have the Dwell and Timing correctly set .

    Be aware that the dizzy's clamp make it tricky to adjust the timing , you must always re-check it after snugging up that danged hard to reach pinch screw . I have a dedicated stubby screw driver just for this .

    Keep us posted , the folks here know everything so ask away ! .
     
  9. brit 50

    brit 50 Member

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    Detail

    Nate, you have this habit of just skipping over the details, it's a bit annoying to be honest:rolleyes:
     
  10. destryrideagain

    destryrideagain Member

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    Alrighty, been in my dads gas station shop all day and had a couple people come by while I was prepping to get some work done. Nate I sure wish you were here in Kansas! Not a one person here thinks the valves need to be even tinkered with but Im with you on this one, so pretty soon here Im gonna go somewhere where no one can bother me, maybe I can find an old barn and setup shop for the day. I sprayed carb cleaner all over carb and manifold to check for vacuum leaks and none found. Got the distributor points taken care and did see that the dis. could be hopping around and got that taken care of. Plug cables and plugs seem fine. Cranked it up and got the timing light set up and the BB mark just wants to jump or drift away so I got clamped it as the best I could get. the engine is running much better than the other day...but it does not want to idle good at all even when HOT. I revved up the throttle and watched the distributor and noticed the advance was not working but there is vacuum at the carb side. Could this be here in where the problem is? I did find an older vacuum gauge but with no fittings yet Nate. Anyways, only other thing I can do is get those valves adjusted and check the float level in the carb right? Talk to y'all later on!

    P.S. I have many printed sheets from Nate and others to keep with me, I do appreciate your advice!
     
  11. vwnate1

    vwnate1 Member

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    ' Cheat Sheets '

    Oh yeah ~ I make up and use 'em too , they're quite handy , I scribble notes on them and then toss out when the job is finshed , thisa way I necver have to get fingerprints on my precious old Tech Manuals...

    I am told there's quite a few binders out there with my technical ramblings , going over many different vehicles and back many years...

    That's it for the week , y'alls have a GREAT WEEKEND ! .

    If I get a chance i'll pop in for a looksee .
     

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