74 2500M: ignition timing
Discussion
Guys, I've been fooling around with my M's timing to find where it runs the sweetest.
I got the best idle by advancing the timing somewhat. Car seems to run well at speed too.
But then I noticed a problem: my starter is hanging up a bit. I assume that means I'll need to retard somewhat.
Unless I'm hearing pinking (none that I've noticed so far), do you think I'm causing any harm by having the timing advanced such that the starter is hanging up a little?
Final point: any consensus on using a vacuum gauge to set timing, rather than a strobe? I gather some swear by it.
Ron
I got the best idle by advancing the timing somewhat. Car seems to run well at speed too.
But then I noticed a problem: my starter is hanging up a bit. I assume that means I'll need to retard somewhat.
Unless I'm hearing pinking (none that I've noticed so far), do you think I'm causing any harm by having the timing advanced such that the starter is hanging up a little?
Final point: any consensus on using a vacuum gauge to set timing, rather than a strobe? I gather some swear by it.
Ron
If the timing is too advanced, engine can fire early enough so that the starter is fighting the 'bang' in the cylinder. Some engines are worse than others for this, but they will all pretty much freeze the starter at some point.
Renaldo - my experience with (UK) Triumph straight sixes was that they pink easily - but I think the TVRs may have had the low compression carb engines intended for US market, which will be more forgiving.
Idle speed will rise even when timing is too advanced, I think. Probably needs to be backed off a little.
the old vac guage method does work, but the highest vacuum was still too advanced as I remember.... It's a long time ago for me though, so my memory is hazy...
May be worth checking the ring gear teeth too, and make sure starter is tight on the bolts. It wouldn't be the first to work loose !
Renaldo - my experience with (UK) Triumph straight sixes was that they pink easily - but I think the TVRs may have had the low compression carb engines intended for US market, which will be more forgiving.
Idle speed will rise even when timing is too advanced, I think. Probably needs to be backed off a little.
the old vac guage method does work, but the highest vacuum was still too advanced as I remember.... It's a long time ago for me though, so my memory is hazy...
May be worth checking the ring gear teeth too, and make sure starter is tight on the bolts. It wouldn't be the first to work loose !
Edited by RCK974X on Friday 20th January 10:34
Thanks guys!
I suppose the problem could simply be the starter working loose (among other things, as mentioned). I put a brand new starter on a year ago, so I'm hoping it's not shot.
Some of the local Triumph TR6 crowd tell me they don't even own a strobe and do their timing with a vacuum gauge. (Who knew?)
I think the theory they're operating on is that with older, worn 6 engines, "factory" precision is largely irrelevent.
And yes, it sounds like maximum vacuum is probably too advanced. But slightly lower is supposed to be about right, as I understand it.
B, sounds like you're sticking with the strobe! Maybe that's the smart thing to do...
I suppose the problem could simply be the starter working loose (among other things, as mentioned). I put a brand new starter on a year ago, so I'm hoping it's not shot.
Some of the local Triumph TR6 crowd tell me they don't even own a strobe and do their timing with a vacuum gauge. (Who knew?)
I think the theory they're operating on is that with older, worn 6 engines, "factory" precision is largely irrelevent.
And yes, it sounds like maximum vacuum is probably too advanced. But slightly lower is supposed to be about right, as I understand it.
B, sounds like you're sticking with the strobe! Maybe that's the smart thing to do...
Renaldo said:
Thanks guys!
I suppose the problem could simply be the starter working loose (among other things, as mentioned). I put a brand new starter on a year ago, so I'm hoping it's not shot.
Some of the local Triumph TR6 crowd tell me they don't even own a strobe and do their timing with a vacuum gauge. (Who knew?)
I think the theory they're operating on is that with older, worn 6 engines, "factory" precision is largely irrelevent.
And yes, it sounds like maximum vacuum is probably too advanced. But slightly lower is supposed to be about right, as I understand it.
B, sounds like you're sticking with the strobe! Maybe that's the smart thing to do...
renaldo , do you have a vacuum advance canister on the distributor ? if so ,make sure its working and not leaking, by sucking on it and seeing if the mechanism moves .I suppose the problem could simply be the starter working loose (among other things, as mentioned). I put a brand new starter on a year ago, so I'm hoping it's not shot.
Some of the local Triumph TR6 crowd tell me they don't even own a strobe and do their timing with a vacuum gauge. (Who knew?)
I think the theory they're operating on is that with older, worn 6 engines, "factory" precision is largely irrelevent.
And yes, it sounds like maximum vacuum is probably too advanced. But slightly lower is supposed to be about right, as I understand it.
B, sounds like you're sticking with the strobe! Maybe that's the smart thing to do...
next step would be to feed this with vacuum from the inlet manifold ,not from the ported take off on the carb ...this way you have max advance at tickover ,but your static advance will be less so its easier on the starter .
regards
robert
Robert, thanks very much for this.
My original Lucas 22D distributor only has a "retard" mechanism on it and I don't think it's working. (the entire distributor is getting a bit loose and sloppy -- ready for a rebuild.)
However,as I understand it, the retard isn't of much use at all -- mainly an emissions thing. Please correct me if I'm wrong.
Regardless, I bought a PowerSpark replacement distributor for my car.
The PowerSpark does have a vacuum advance and completely electronic components, so I think I can follow your advice once I've got the new dizzy in place. Any other thoughts or suggestions would be much appreciated.
Ron
My original Lucas 22D distributor only has a "retard" mechanism on it and I don't think it's working. (the entire distributor is getting a bit loose and sloppy -- ready for a rebuild.)
However,as I understand it, the retard isn't of much use at all -- mainly an emissions thing. Please correct me if I'm wrong.
Regardless, I bought a PowerSpark replacement distributor for my car.
The PowerSpark does have a vacuum advance and completely electronic components, so I think I can follow your advice once I've got the new dizzy in place. Any other thoughts or suggestions would be much appreciated.
Ron
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