I recently had the distributor gear snap so needed to readjust timing.
Its a Turbo 202, i adjusted the timing to 10degrees advanced and it seems to be running a little smoother and blowing a bit less smoke.
The engine is a little harder to start tho (but still no problem) just takes a little longer cranking and splutters a bit as it starts. Also turning the engine off is a little rougher, after the engines been off maybe 4-5 seconds later the car will backfire.
But it does run smoother, does this sound right?
Im guessing the timing used to be less advanced before, so thats probably why it used to start easier, but not run quite as smooth.
I dont know too much about adjusting timing, so can anyone advise anything? such as maybe a better adjustment for my timing, does 10 sound ok?
Thanks
Adjusting timing for a turbo 202
Started by
_mike_nofx_
, Jun 24 2006 03:31 PM
11 replies to this topic
#2
makka
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Posted 24 June 2006 - 03:50 PM
i would back it off, its over advanced if it keeps going after its turned off? does it ping under hard acceleration? put it in third while cruising and accelerate hard and see if it pings
#3
_torana_
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Posted 24 June 2006 - 04:55 PM
hi mike
turbo/supercharger timing is a totally different ballpark to non forced induction timing.
First off all, turbo/supercharged motors love the timing to be advanced. But to much and POP. Youll detonate your motor. So finding that point where the motor just starts to ping, and then back off a bit seems to be the nicest spot.
Where is you dissy vaccum advance connected to?
It can be in either of the two.
1: Pre the turbo, so it does get vaccum, but this is a bad sceanrio, as this will advance your timing when you give it a boot full, which could kill your motor and make it ping.
2: After the turbo, it will get vaccum when not in boost , but under boost will do nothing, so you may as well remove it all together, and your car may run smoother when not on boost.
What you ultimately want is a distributor that attaches after the turbo, so when it comes on boost it retards the timing, but holden never made one ( unless the turbo slt had one ( can anyone help ) )
You can buy boost retard diaphrams for distributors, and if youre handy with the tools you could mod a dizzy for this sceanario.
But if you aint, leave the dizzy unconected, set your timing and drive. If it pings, back it off a bit, and test again. You may have to compamize for ease of starting, plus be carefull as backfires can and will damage your turbo if done to much.
Hope this helps
cheers julian
check this website for a more info on boosted timing
http://www.fefcholde...ge/norman5.html
turbo/supercharger timing is a totally different ballpark to non forced induction timing.
First off all, turbo/supercharged motors love the timing to be advanced. But to much and POP. Youll detonate your motor. So finding that point where the motor just starts to ping, and then back off a bit seems to be the nicest spot.
Where is you dissy vaccum advance connected to?
It can be in either of the two.
1: Pre the turbo, so it does get vaccum, but this is a bad sceanrio, as this will advance your timing when you give it a boot full, which could kill your motor and make it ping.
2: After the turbo, it will get vaccum when not in boost , but under boost will do nothing, so you may as well remove it all together, and your car may run smoother when not on boost.
What you ultimately want is a distributor that attaches after the turbo, so when it comes on boost it retards the timing, but holden never made one ( unless the turbo slt had one ( can anyone help ) )
You can buy boost retard diaphrams for distributors, and if youre handy with the tools you could mod a dizzy for this sceanario.
But if you aint, leave the dizzy unconected, set your timing and drive. If it pings, back it off a bit, and test again. You may have to compamize for ease of starting, plus be carefull as backfires can and will damage your turbo if done to much.
Hope this helps
cheers julian
check this website for a more info on boosted timing
http://www.fefcholde...ge/norman5.html
#4
_mike_nofx_
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Posted 25 June 2006 - 07:57 AM
Thanks for the advice Julian, thats great help.
I'll have to check where the vacuum is connected later, cause im not sure!
I also have water injection which should help a bit.
Thanks
I'll have to check where the vacuum is connected later, cause im not sure!
I also have water injection which should help a bit.
Thanks
#5
_mike_nofx_
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Posted 25 June 2006 - 08:29 AM
Just read this in that article:
"A 'hot' motor operating on 10 to 1 with a fifteen pound supercharge has an effective ratio of about 13 to 1, which methanol easily copes with. This fuel has another very great advantage it has a latent heat value of about three times that of petrol, of which more later. This means that it is a far better coolant of superchargers, valves etc. As a fuel however it suffers from the disadvantage that it has only about 40% the energy content of petrol, pound for pound, and must therefore be used in much greater quantity. This problem never seems to trouble its advocates even at $1 per gallon."
Is he saying thats cheap or expensive for the fuel?
"A 'hot' motor operating on 10 to 1 with a fifteen pound supercharge has an effective ratio of about 13 to 1, which methanol easily copes with. This fuel has another very great advantage it has a latent heat value of about three times that of petrol, of which more later. This means that it is a far better coolant of superchargers, valves etc. As a fuel however it suffers from the disadvantage that it has only about 40% the energy content of petrol, pound for pound, and must therefore be used in much greater quantity. This problem never seems to trouble its advocates even at $1 per gallon."
Is he saying thats cheap or expensive for the fuel?
#6
rodomo
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Posted 25 June 2006 - 10:20 AM
I was talking to my engine builder buddy about timing and advance yesterday.
He reckons for any any track work disconnect the vacuum advance as it is only effective at cruise with steady throttle position. Obviously reconnect for highway work. Anything with high compression or forced induction needs less overall mechanical advance as the high comp or forced induction advances ignition (not spark) anyway. He club races a turbo 2litre bluebird and has a "fixed" (no advance) dizzy and runs about 15 degrees static advance.
He reckons for any any track work disconnect the vacuum advance as it is only effective at cruise with steady throttle position. Obviously reconnect for highway work. Anything with high compression or forced induction needs less overall mechanical advance as the high comp or forced induction advances ignition (not spark) anyway. He club races a turbo 2litre bluebird and has a "fixed" (no advance) dizzy and runs about 15 degrees static advance.
#7
Litre8
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Posted 25 June 2006 - 10:55 AM
My old Turbo 6 had a total advance of 34 degrees, static of 16 degrees and mechanical of 18 degrees. It was a draw through setup so the vacuum advance was connected to upstream of the turbo.
I had an ignition killswitch that allowed the engine to get cranking before I switched on the ignition (overcoming the hard cranking issues with big initial advance). I think Wayne mahnken with his 650hp 202 circuit car used to run a locked timing of 32 degrees.
I had an ignition killswitch that allowed the engine to get cranking before I switched on the ignition (overcoming the hard cranking issues with big initial advance). I think Wayne mahnken with his 650hp 202 circuit car used to run a locked timing of 32 degrees.
#8
turbotrana
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Posted 25 June 2006 - 02:34 PM
I run a maximum timing of around 28 degrees at max load and boost. A friend of mine with a similar setup said he can advance it more but he gets no more power on the dyno.
Prior to programable EMS I used to run a blue mtr dizzy, take it apart, bend one of the tabs on the dizzy to lock one side of the balance weights (sorry cant remember which side but I think the side with the thicker tab) so that the mechanical advance only advanced around 7degrees fom memory.
I then set the base timing at around 20 degrees.
I still used the vacum advance cause this is what gives you your fuel economy and only works under vacum, not boost.
But remember only use 98 octane fuel
Prior to programable EMS I used to run a blue mtr dizzy, take it apart, bend one of the tabs on the dizzy to lock one side of the balance weights (sorry cant remember which side but I think the side with the thicker tab) so that the mechanical advance only advanced around 7degrees fom memory.
I then set the base timing at around 20 degrees.
I still used the vacum advance cause this is what gives you your fuel economy and only works under vacum, not boost.
But remember only use 98 octane fuel
#9
_mike_nofx_
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Posted 29 June 2006 - 05:36 PM
Ok, The vacuum hose goes to a plastic box above the thermostat, then another hose goes from that small box to the carbs. As its a suck through set up, its before the Turbo, so what does anyone make of that?
Does that sounds like how it is supposed to be?
Thanks
Does that sounds like how it is supposed to be?
Thanks
#10
Litre8
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Posted 29 June 2006 - 09:24 PM
I think in your case the vacuum advance is disabled until the engine reaches a certain temperature. If your dizzy canister isnt one that supports retard and advance then it sounds like its plumbed correctly.
#11
_mike_nofx_
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Posted 29 June 2006 - 10:57 PM
Ok, cool. 1 question on the temperature activated advance, can this be adjusted? As i dont know what it would be set to, and maybe its set at a higher temperature than my cars engine could reach (maybe paranoid)
Of the 4 or 5 bigger bars on the thermometer gauge, mine sits pretty much always on the first big bar. In winter its just under the first big bar, and in summer its just over. It sounds low to me, (i would think around half way would be normal?) so maybe this isnt enough for the vac advance to fully work. just a thought.
And, i suppose theres no way to tell what the vac advance reaches without a dyno, is there?
Mechanical advance can be checked just by revving in neutral right?
Sorry bout all the questions! im a bit thick sometimes
Of the 4 or 5 bigger bars on the thermometer gauge, mine sits pretty much always on the first big bar. In winter its just under the first big bar, and in summer its just over. It sounds low to me, (i would think around half way would be normal?) so maybe this isnt enough for the vac advance to fully work. just a thought.
And, i suppose theres no way to tell what the vac advance reaches without a dyno, is there?
Mechanical advance can be checked just by revving in neutral right?
Sorry bout all the questions! im a bit thick sometimes
#12
Litre8
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Posted 29 June 2006 - 11:24 PM
You can test the vacuum advance by the idle method too.
Run a piece of rubber hose from the canister to a T piece. One side goes to a vacuum guage, the other to a vacuum source (either pump or your mouth).
Evacuate some air, note the vacuum guage reading and also note the timing change as shown with a timing light. Repeat this for different vacuum readings.
Unless you car is fully ADR compliant (maybe not with the turbo ?) bypass the vacuum /thermostat fitting and just run the vacuum line from the dizzy canister to either a constant or ported vacuum source (which one you use may be determined by the idle quality when its hooked up).
Run a piece of rubber hose from the canister to a T piece. One side goes to a vacuum guage, the other to a vacuum source (either pump or your mouth).
Evacuate some air, note the vacuum guage reading and also note the timing change as shown with a timing light. Repeat this for different vacuum readings.
Unless you car is fully ADR compliant (maybe not with the turbo ?) bypass the vacuum /thermostat fitting and just run the vacuum line from the dizzy canister to either a constant or ported vacuum source (which one you use may be determined by the idle quality when its hooked up).
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