Charles,
I find TDC by using a dial indicator on the piston and move the crankshaft either side of TDC in both directions to get the same reading. Mark the flywheel. Repeat and repeat. TDC is mid way between the marks.
I am not sure what you are trying to imply or say. Is it that you think that I (and Jon and Keith P) have made a complete hash of this measurement? You are probably quite right to question me (I am certainly prone to measurement finger trouble!), although I did give most of the details and tried to estimate measurement errors on this topic on 12th November last year.
I trust Jon and Keith's results. I really don't think that the answer lies in suggesting that we have all made a 20/25 degree error (in the same direction) in determining TDC.
Have you measured the advance on a (apparent) bog standard engine? What result did you get?
Bruce - Have you got any results for the ignition advance angle?
Jeremy
FV Ignition Timing
Moderators: John@sos, charlesp, Charles uk, RickUK, Petergalileo
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Charles uk
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Re: FV Ignition Timing
Jeremy the problem with using the DTI method is unless it's screwed into the plug threads or better still securely fastened 90 degrees to the head, so it's always touching the same place on the sloping piston crown, it's not accurate enough, considering that the piston on a silver century moves only 4 thou, between 5 degrees BTDC & TDC.
Sorry to be a bit anal on this, but anyone that knows me, will tell you that I build Cathedrals, when all I need is an outside loo!
Sorry to be a bit anal on this, but anyone that knows me, will tell you that I build Cathedrals, when all I need is an outside loo!
Make it idiot proof and someone will make a better idiot.
Re: FV Ignition Timing
Sorry to be a bit anal on this, but anyone that knows me, will tell you that I build Cathedrals, when all I need is an outside loo!
An unfortunate image, Charles. I hope it does not feature in my nightmares...
An unfortunate image, Charles. I hope it does not feature in my nightmares...
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Charles uk
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Re: FV Ignition Timing
If I can find my camera I will try & show how I do it.
I drill & tap a pointer to the ignition base plate, mark TDC onto the lower circumference of the flywheel using the piston stop method, then attach a sticky label that has degree marks that are 1/360 of the circumference at the pointer height, looks like a ruler, & use an old strobe that doesn't have all modern dwell crap inside it.
I drill & tap a pointer to the ignition base plate, mark TDC onto the lower circumference of the flywheel using the piston stop method, then attach a sticky label that has degree marks that are 1/360 of the circumference at the pointer height, looks like a ruler, & use an old strobe that doesn't have all modern dwell crap inside it.
Make it idiot proof and someone will make a better idiot.
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Collector Inspector
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Re: FV Ignition Timing
You will drill and tap a pointer after finding TDC of course.
You do it Charles.....................saves my time etc.
Else I am just watching how the thread goes...................
Cheers
B
You do it Charles.....................saves my time etc.
Else I am just watching how the thread goes...................
Cheers
B
A chicken is one egg's way of becoming others
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Charles uk
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Re: FV Ignition Timing
Before Bruce, try it & see.
Make it idiot proof and someone will make a better idiot.
Re: FV Ignition Timing
Charles,
Sounds a very accurate method indeed.
My dial indicator method is probably only accurate to wthin +/- 3deg.
Your method is considerably better and I suspect is within +/- 1deg.
However these ptential errors are not even in the same order of the 20/25 deg discrepancy that we are looking for.
What results do you get when you measure an ordinary/standard/normal engine? Please don't ask me to define that! i am trying to say the engines that I, Keith and Jon have measured.
I hope Bruce, will use his knowledge, skill and extensive experience (nothing like obvious flattery to try to persuade somebody!) to give us some results.
Jeremy
Sounds a very accurate method indeed.
My dial indicator method is probably only accurate to wthin +/- 3deg.
Your method is considerably better and I suspect is within +/- 1deg.
However these ptential errors are not even in the same order of the 20/25 deg discrepancy that we are looking for.
What results do you get when you measure an ordinary/standard/normal engine? Please don't ask me to define that! i am trying to say the engines that I, Keith and Jon have measured.
I hope Bruce, will use his knowledge, skill and extensive experience (nothing like obvious flattery to try to persuade somebody!) to give us some results.
Jeremy
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Charles uk
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Re: FV Ignition Timing
The other Charles & I, have had this discussion before Jeremy, & as everyone seems to use this site as a reference site, including most of the other Seagull sites as illustrated by them making the same typos that we did, we decided all the "facts" posted on here, had to be as accurate as possible,
CharlesP researched the historical side due to his interest & location & I did the technical side as I have owned & worked on every model of Seagull from 1931 to 1994 except a longshaft 102+ & the little F, though CharlesP did much of the work on the little 40's as he loved them with a strange obsession.
Between Charles & I we have managed to obtain a large collection of Seagull's R&D technical reports & engineering drawings, that we pool to assist each other in our chosen research areas.
The communication between Charles & myself with regard to facts & fables about British Seagull, has been going on for more than 10 years now, & seldom have I seen him as happy as you made him with the data you've started pulling out of your little 40's database.
Seagull's own timing figures for their CDI ignitions were 22 to 25 degrees BTDC (see service manual) & these were ignitions that were quoted as being suitable for fitting in place of faulty Villiers mk 1, though it's possible that this might be in error in this case.
I can't remember where CharlesP got the 23.5 figure from, but our normal arguement stopper is "show me documentary evidence" he must have shown me where this came from as I don't remember fighting over this.
CharlesP researched the historical side due to his interest & location & I did the technical side as I have owned & worked on every model of Seagull from 1931 to 1994 except a longshaft 102+ & the little F, though CharlesP did much of the work on the little 40's as he loved them with a strange obsession.
Between Charles & I we have managed to obtain a large collection of Seagull's R&D technical reports & engineering drawings, that we pool to assist each other in our chosen research areas.
The communication between Charles & myself with regard to facts & fables about British Seagull, has been going on for more than 10 years now, & seldom have I seen him as happy as you made him with the data you've started pulling out of your little 40's database.
Seagull's own timing figures for their CDI ignitions were 22 to 25 degrees BTDC (see service manual) & these were ignitions that were quoted as being suitable for fitting in place of faulty Villiers mk 1, though it's possible that this might be in error in this case.
I can't remember where CharlesP got the 23.5 figure from, but our normal arguement stopper is "show me documentary evidence" he must have shown me where this came from as I don't remember fighting over this.
Make it idiot proof and someone will make a better idiot.
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Charles uk
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Re: FV Ignition Timing
Just had a thought how we can answer this, I belive CharlesP has a crankshaft drawing for the SJP that gives the angle between the Woodruff key & the center of the bigend pin, can you dig this out Charles if you read this.
Jeremy do you have a little 40 crank that is at liberty that you can measure this angle on, within 5 degrees should be close enough, as the flywheels are exchangeable.
Jeremy do you have a little 40 crank that is at liberty that you can measure this angle on, within 5 degrees should be close enough, as the flywheels are exchangeable.
Make it idiot proof and someone will make a better idiot.
Re: FV Ignition Timing
That sounds an excellent idea. Yes, I will have shortly (probably 3 weeks away) an FV crank assembly. I will have a go at measuring it.
Comparing the angular position of the woodruff key from the big end to the similar angle on the SJP drawing might not be conclusive. If the angle on the FV crank turns out to be the same as the angle on the SJP crank drawing, then we can conclude that the FV/FVP has the same timing as the SJP/SJM.
I apologise for being a bit of a bore on this subject. I am merely asking what is the timing advance on early series 40. (ie F, FV, FVP and LS).
By the way, I don't think it is, as you suggest, a 'strange obsession' to love the Lttle 40s - well not much of one!!!
Thank you also for pointing out the significance of this site in respect of it being a reference source and facts should be just that - correct and precise.
My Early Forty data base is an attempt to record the physical reality of surviving engines for people to use as a reference. The measuring of the timing advance and trying to collect that data from other engines - preferably Early 40 engines - is a similar exercise in recording the physical reality. We must note, measure and record the data ina systematic way.
Jeremy
Comparing the angular position of the woodruff key from the big end to the similar angle on the SJP drawing might not be conclusive. If the angle on the FV crank turns out to be the same as the angle on the SJP crank drawing, then we can conclude that the FV/FVP has the same timing as the SJP/SJM.
I apologise for being a bit of a bore on this subject. I am merely asking what is the timing advance on early series 40. (ie F, FV, FVP and LS).
By the way, I don't think it is, as you suggest, a 'strange obsession' to love the Lttle 40s - well not much of one!!!
Thank you also for pointing out the significance of this site in respect of it being a reference source and facts should be just that - correct and precise.
My Early Forty data base is an attempt to record the physical reality of surviving engines for people to use as a reference. The measuring of the timing advance and trying to collect that data from other engines - preferably Early 40 engines - is a similar exercise in recording the physical reality. We must note, measure and record the data ina systematic way.
Jeremy
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Charles uk
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Re: FV Ignition Timing
I spoke to Jon (headdownarseup) last night & it seems he has run his FV with a CDI ignition set in the 64cc position on the woodruff key, which ran perfectly with no problems at all, which would imply that the FV, F, FVP timing is set at the standard 23.5 degree position.
I can't work out where the 50 degree reading is coming from, other than from incorrect usage of the modern strobe light.
Can anyone offer any clues?
I can't work out where the 50 degree reading is coming from, other than from incorrect usage of the modern strobe light.
Can anyone offer any clues?
Make it idiot proof and someone will make a better idiot.
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Collector Inspector
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Re: FV Ignition Timing
Woodrufffffffff key.
Now there is an interesting extra indeed.
Ads something else to the initial.
Evolves as we go aye?
And so it should as this is now getting some thought going between parties.
B
Now there is an interesting extra indeed.
Ads something else to the initial.
Evolves as we go aye?
And so it should as this is now getting some thought going between parties.
B
A chicken is one egg's way of becoming others
Re: FV Ignition Timing
Charles,
You wrote:-I can't work out where the 50 degree reading is coming from, other than from incorrect usage of the modern strobe light.
Can anyone offer any clues?
The simple answer is that Keith P, Jon and myself have measured a total of six, Forty series engines and have all got results of 40 to 50 degrees.
We have been over and over this, and I know that you fully aware of it. It is no good blaming these unexpected results on the inability to use a strobe light, or to set TDC accurately, or anything else. The results are the results. The fact that they are unexpected to you, does not make them wrong.
Jeremy
You wrote:-I can't work out where the 50 degree reading is coming from, other than from incorrect usage of the modern strobe light.
Can anyone offer any clues?
The simple answer is that Keith P, Jon and myself have measured a total of six, Forty series engines and have all got results of 40 to 50 degrees.
We have been over and over this, and I know that you fully aware of it. It is no good blaming these unexpected results on the inability to use a strobe light, or to set TDC accurately, or anything else. The results are the results. The fact that they are unexpected to you, does not make them wrong.
Jeremy
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Charles uk
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Re: FV Ignition Timing
Jeremy I'm not say that you don't have the ability to use a strobe, just that a strobe designed for a 4 stroke motor might not be the right tool for this job.
It's quite possible that your right with the 50 degree figure but to my sense of logic, I'm not convinced that a motor from the same basic family tree would have an ignition point so far advanced.
Prove me wrong in my assumptions & I'll be only to pleased to apologise.
Bruce did I make a mistake in my spelling?
It's quite possible that your right with the 50 degree figure but to my sense of logic, I'm not convinced that a motor from the same basic family tree would have an ignition point so far advanced.
Prove me wrong in my assumptions & I'll be only to pleased to apologise.
Bruce did I make a mistake in my spelling?
Make it idiot proof and someone will make a better idiot.
Re: FV Ignition Timing
Charles,
I am not trying to prove anything. I am certainly not interested in trying to prove your assumptions are wrong. I am also not after any apology.
I am just collecting data concerning early series 40s - specifically in this case the timing advance figure.
This topic started because I had trouble starting and running an FV (not for the first time and I am sure it will not be the last!!).
In trying to resolve this, I wondered if the ignition timing was correct. I thought that perhaps wrong components had been fitted. I measured the timing advance and found 50deg. I thought this was large and wondered whether any other FV/FVP owner would measure their engines. Keith and Jon did and reported simliar figures in the 45 - 50 deg. I therefore looked elsewhere for the poor running and starting problems. I eventually resolved this without any more concern about the timing.
Jeremy
I am not trying to prove anything. I am certainly not interested in trying to prove your assumptions are wrong. I am also not after any apology.
I am just collecting data concerning early series 40s - specifically in this case the timing advance figure.
This topic started because I had trouble starting and running an FV (not for the first time and I am sure it will not be the last!!).
In trying to resolve this, I wondered if the ignition timing was correct. I thought that perhaps wrong components had been fitted. I measured the timing advance and found 50deg. I thought this was large and wondered whether any other FV/FVP owner would measure their engines. Keith and Jon did and reported simliar figures in the 45 - 50 deg. I therefore looked elsewhere for the poor running and starting problems. I eventually resolved this without any more concern about the timing.
Jeremy