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Retarded Engine
https://www.ausmini.com/forums/viewtopic.php?f=2&t=1767		 Page 1 of 1
Author:  68matic [ Thu Sep 02, 2004 9:43 pm ]
Post subject:  Retarded Engine
i played around with the timing in my dizzy

now my engine is EXTREMELY quiet.
the only thing that tells you the car is on, when you are in it,
is the vibration of the steering column under your hands
and the little taps of the rockers.

sometimes when you put your foot down, it stutters twice and revs up normally
it has no trouble goin up hills

steve (and mikey) and bob told me "your engines retarded"
with a straight face
they said i could turn the car on, tap the dizzy this way
get rid of the popping in the exhaust

or tap it the other way whilst the car is on
and just listen for just the right sound coming out of the exhaust

is it so straight forward? (he did it to all of his cars and they're fine)
Author:  Anto [ Thu Sep 02, 2004 9:50 pm ]
Post subject: 
When I fitted my Aldon electric ignition, I had to redo my ignition timing afterwards (so say the instructions). I was at work, hence no strobe light. Hell, don't need one! I just drove up and down the road at high speed, tweaking the dizzy. I simply advanced it as much as I could until it started pinging and then retarded it slightly. Works a treat.

A note of warning though. I'm told it is a bad idea to leave the dizzy bolt loose whilst doing this. A friend of mine had a problem with his Morris Minor, using this ignition timing method, where the dizzy actually popped out of the motor whilst driving!! I kid you not! It made a very loud bang and the engine stopped... a bit concerning.
Author:  drmini in aust [ Thu Sep 02, 2004 10:02 pm ]
Post subject: 
68matic wrote:
i played around with the timing in my dizzy

now my engine is EXTREMELY quiet.
the only thing that tells you the car is on, when you are in it,
is the vibration of the steering column under your hands
and the little taps of the rockers.

sometimes when you put your foot down, it stutters twice and revs up normally
it has no trouble goin up hills

steve (and mikey) and bob told me "your engines retarded"
with a straight face
they said i could turn the car on, tap the dizzy this way
get rid of the popping in the exhaust

or tap it the other way whilst the car is on
and just listen for just the right sound coming out of the exhaust

is it so straight forward? (he did it to all of his cars and they're fine)


Short answer is NO,as there are too many variables involved in the build of various engines.

You can get it close, listening to it at idle, (IF the dizzy has the right advance curve and is not worn, etc) but what really matters for power production is that the timing advance is right at 4000 rpm and above.
`Power timing' involves advancing the dizzy a degree or two at a time and checking for improvement while accelerating in 4th gear. If the motor starts to ping at low speed, or it starts to get rough, you have gone too far- retard it a bit until it stops pinging.

I set mine at above 4000 rpm with a timing light, to a mark on the crank pulley that I have found gives the best (`seat of pants') power. With my particular engine (with strange bits and mods in it and no vacuum advance) this is just over 40 degrees... :shock:
I could care less what the advance is at idle. :wink:
Author:  68matic [ Thu Sep 02, 2004 10:07 pm ]
Post subject: 
thanks friends, i was gonna do it myself
but maybe wait till i have someone look at it properly
Author:  68matic [ Mon Sep 06, 2004 3:52 pm ]
Post subject: 
i was told that running a retarded engine is very bad
it can put a hole in your piston head and creak a conrod
is this true?
Author:  mickmini [ Mon Sep 06, 2004 6:23 pm ]
Post subject: 
Duc

methinks you are referring to an engine with the timing too far advanced. If you advance the timing too much or you get detonation (preignition, knocking, pinging) this basically means that the mixture is igniting when the piston is still on its way up the bore on the compression stroke. A little bit of that action is ok. The Dr says his is 40* advanced which means his spark occurs when the crankshaft is at 40* prior to the piston getting to the top.

A LOT of that kind of action, especially from detonation, means that there is too much opposing force trying to push the crank back around the wrong way, and causing imbalances. Detonation is not constant and predictable like the timed spark, so this is where the damage comes from. My brother's race car was runing leaner on a couple of cylinders because the injectors got gummed up. He did not take my advice after the detonation destroyed main bearings, to get the injectors cleaned and balanced. The next engine he put together still ran lean and the detonation resulted in a burned a hole in a piston.

don't think you'll do too much damage if the timing is a bit retarded, you just lose power, because the spark goes off when the piston is already on its way down.

michael
Author:  drmini in aust [ Mon Sep 06, 2004 7:50 pm ]
Post subject: 
If it's retarded it will feel `flat' at low revs, ie poor throttle response, no `go' when you prod it. Fuel economy will be poor and it will tend to overheat more.

If it's over advanced, it will ping at low revs and get rough at high revs- and the detonation will not help the pistons or bearings.

Somewhere in the middle between these, there's a happy medium where it goes well. Find it, then put a timing light on and mark the crank pulley, so you can set it there in future. :wink:
Author:  68matic [ Mon Sep 06, 2004 7:51 pm ]
Post subject: 
thanks meckair (thats how it should be said)
it makes alotta sense the way you say it
im not even sure if its fair too advanced or retarded, just that its really quiet.
what kinda sounds came out in your brother's case coz i cant really imagine a piston slap
Author:  PhildoD [ Mon Sep 06, 2004 9:01 pm ]
Post subject: 
Piston slap is a different thing altogether, usually from an eccentric bore, or worn gudgeon pin. Pinging(pinking, detonation, pre-detonation) is when the combustion occurs too early, trying to force the piston backards, and causing a lot of stress on all of the components. Advancing your timing too far can make the car difficult to start, cause a very noticeable rattle at low rev's and high power settingand possibly over running on shutdown.

Retarding the timing too far can also cause damage, but usually will make itself known in poor performance.
Author:  68matic [ Tue Sep 07, 2004 12:48 am ]
Post subject: 
thanks phildo
Author:  mickmini [ Tue Sep 07, 2004 11:10 pm ]
Post subject: 
Sound? at about 6000 (redlined at 8000) it went BANG :!: instant oil smoke everywhere including in the cabin. He had the video running at the time, and it's amazing he could see his way to the pits.

The first engine that destroyed the main bearing was more of a rumble.

But these were toyota 4AGE not BMC A series.

michael
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