Author Topic: Timing on BIS  (Read 500 times)

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andyzeetec

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Timing on BIS
« on: July 19, 2020, 10:47:43 PM »
Hi all. Adjusted contact breaker points today, then checked and set the timing using the static timing method. I also decided to try the strobe gun which gave a different result so required adjustment, rotated the dizzy which resulted in decreased idle, subsequently I increased the idle rpm to compensate. Yet to go for a test drive to see if satisfactory.
So my question is.. any ideas why I get differing results using static timing vs strobe method?  :-

Thanks.
« Last Edit: July 19, 2020, 10:49:34 PM by andyzeetec »

ChrisRLewis

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Re: Timing on BIS
« Reply #1 on: July 19, 2020, 11:05:55 PM »
Did you disconnect the vacuum advance on the distributor and blank it off when doing the strobe timing?

andyzeetec

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Re: Timing on BIS
« Reply #2 on: July 20, 2020, 08:50:59 AM »
Did you disconnect the vacuum advance on the distributor and blank it off when doing the strobe timing?

Disconnected vacuum hose at dizzy, but didnt blank it off.

ChrisRLewis

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Re: Timing on BIS
« Reply #3 on: July 20, 2020, 08:58:08 AM »
Another few things to check is that the centrifugal advance on the distributor is working correctly, not worn, sticky or problems with the springs. Timing using the static method is a bit hit and miss if you have a worn distributor, if you have a dwell meter check the readings.

With the strobe light timing setting what is this reading giving using the static method?
« Last Edit: July 20, 2020, 09:01:28 AM by ChrisRLewis »

andyzeetec

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Re: Timing on BIS
« Reply #4 on: July 20, 2020, 06:49:25 PM »
Another few things to check is that the centrifugal advance on the distributor is working correctly, not worn, sticky or problems with the springs. Timing using the static method is a bit hit and miss if you have a worn distributor, if you have a dwell meter check the readings.

With the strobe light timing setting what is this reading giving using the static method?

The advance seems to work when revved, not sure how to check springs etc..

Tried timing up again as per fiat workshop manual with strobe, but plugged vacuum pipe this time, but made no difference.

When attempting to read the timing, the marks are jumping back and forth making it difficult to determine exactly where I have it set. Should the mark be steady?
Could that be worn bushings in the distributor or just rough idle issues.

Thanks.

ChrisRLewis

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Re: Timing on BIS
« Reply #5 on: July 20, 2020, 07:33:58 PM »
The timing mark should be fairly steady when using a strobe. Sounds like you have a worn distributor or something is wrong with centrifugal advance/bob weights etc.

Guldbergdk

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Re: Timing on BIS
« Reply #6 on: July 21, 2020, 03:39:38 PM »
Im doing the excact same thing at the moment. With the stobe my mark is jumping around some as well. Ill try and do video when I get back to the shop.

andyzeetec

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Re: Timing on BIS
« Reply #7 on: July 21, 2020, 08:53:26 PM »
I'll be interested too see your video Guldbergdk

Anyhow just had a look, if I rotate the shaft, positioning on cam (points open) and apply sideways/radial pressure, I can open the preset 0.5mm gap by a further 0.2mm (watch first part of video showing gap opening/closing), totalling 0.7mm, so clearly I have some cross axis/radial play on the shaft. Not sure how significant that would be?

At tickover I believe this maybe the cause of the strobed eratic timing marks? At higher revs I would imagine the timing marks will be steady. Any thoughts?

There is also some up/down or axial play (second part of video) which I believe is normal.

« Last Edit: July 22, 2020, 07:17:43 AM by andyzeetec »

Guldbergdk

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Re: Timing on BIS
« Reply #8 on: July 21, 2020, 09:30:11 PM »
Interesting. I have to try that as well.

Would sure be nice with an electronic distributor.

Im having a hard time getting it idle at lower rpm than
1000. Probably because I didnt blank of the vacuum before adjusting. Ill have to try and readjust.


126redbomb

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Re: Timing on BIS
« Reply #9 on: July 30, 2020, 10:31:43 AM »
Hi to all.
  Where is the best place to buy a new dizzy (Cheapest).
The ball bearing/clip (haven't got a clue what it's called) which is on the base plate doesn't flick back very easy. Would this cause the same issues.

andyzeetec

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Re: Timing on BIS
« Reply #10 on: July 30, 2020, 02:57:30 PM »
Hi to all.
  Where is the best place to buy a new dizzy (Cheapest).
The ball bearing/clip (haven't got a clue what it's called) which is on the base plate doesn't flick back very easy. Would this cause the same issues.

Unlikely you will be able to buy a new one, but there are companies out there which will recondition yours. Not sure what you mean by ball bearing clip. If its a BIS, is it a Marelli (alen key adjustment)  or a Zelmot (screw adjustment)?


126redbomb

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Re: Timing on BIS
« Reply #11 on: July 30, 2020, 10:07:38 PM »
Mine is a Zelmot. I will take a photo tomorrow (if I can figure out how I can post it ::))
So if I bought a Marrelli it would fit a Bis?. I bought a spare zelmot of ebay but I don't think it was any good.

126redbomb

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Re: Timing on BIS
« Reply #12 on: August 13, 2020, 09:56:49 AM »
Doh, I forgot to post a picture  ::) I did try to post a video but I gave up :$






 

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