Stock 4K, Ignition Timing And Idling Speed?

[TheHeadShaver noob]

Hi

 

I have two Ke70's with stock 4K engines and I'm having a bit of a problem with setting the timing perfectly.

 

In my Tune-up book it says the ignition timing should be set at 8 degrees with a strobe light, idling between 700-850rpms.

 

However, set to idle at 800rpms and ignition at 8 degrees, both my cars idles kinda rough, like jumping a bit up and down on the idlespeed.

 

One of my ke70's i bought just a few days ago and it was ideling pretty nice, but timing was at like 15degrees and idlespeed was set at 1000. That idlespeed feels and sounds kinda fast but I'm not sure whats normal on theese engines.

 

I don't notice any diffrence while driving tho either when its set at 15 or 8 degrees.

 

I'm thinking if the numbers in my book is wrong, or if it should be set diffrently cuz of wear and tear over the years, or should u just adjust the timing at 800 rpms, then when its correct just turn the idlescrew in until it idles nicely?

 

What do u guys think? any tips on how to set it? and do you guys know what idlespeed and timing ur cars run on?

 

On both cars the points and valves are newly adjusted and new sparkplugs and airfilters.

 

Thanks in advance for all ur help :yes:

[Evan G]

did you adjust the idle mixtures? screw on the bottom of the carby. screw it in till it runs rough then back it out half a turn.

 

ilde should be around 800 manual 850 auto. timing around 10 degrees

 

 

i currently got my timing set to around 12. idle around 700 and the idle mixtures set a little lean (has a mean idle :D)

[altezzaclub]

Mine's at 1000rpm as it drops when the headlights come on, it's idling lean around 19:1. Timing is 12ish, and it doesn't pink if you boot it at low revs on 95octane alcohol.

 

What octane fuel are you using Tom, and what altitude are you at? Orange is at 850m and in the past I've had it running fine here but pinking down at Sydney from the thicker air. Its doesn't do that with the current settings.

[TheHeadShaver noob]

Thanks for ur answers.

 

I'm running on 95 octane and I'm around 140 meters above sealevel, but I'm in Norway, so its pretty cold here now during winter.

 

I havent touched the mixture screw since I'm worried about messing it up, i did that on my other ke70 and i had a heck of a time getting it all back to normal, but maybe i will try screw it in a lil.

 

So basicly i should aim for around 12 degrees and just set the idle where it runs smooth, anywhere from 700-1000 rpms?

 

when it was at 15 degrees i didnt get any timing pinging/knocking so I'm sure i wont get that at 12 either.

 

Do you guys disconnect the vacum advance hose/tube when u set the ignition? if so, should i block the hose that goes into the carby so it doesnt suck "false" air?

 

I also wonder about that adjusting knob on the dizzy thats covered by a plastic cap, what is it really for? does it matter how it sits when i adjust the timing? is it just for fine tuning the timing or does it have another mission?

 

Thanks again for all ur help :)

Edited January 16, 2011 by TheHeadShaver noob

[KENut]

Yep pull the vac advance hose off and block it, and the little knob thing is an octane thingy, quickly adjusts the timing if you change what octane fuel you're using.

[TheHeadShaver noob]

Thanks for ur answer, i will give that a try as soon as it stop snowing. Just spendt 5 hours with the snowblower :bash:

 

Is it any point in getting a electronic dizzy? any advantages cept u don't have to mess with the breakerpoints?

 

If so, are they hard to come by and do i need anything else like coil etc?

 

Thanks again :yes:

[Jlews88]

My ke70 has Webber carbs and lumpy cams I have tryed setting the electronic ignition distributor.and I can't reach the timeing mark the vacuum advance is not working on it when I accelerate.can u please help me! I'm lost for everything else

[Banjo]

Lumpy cams rarely provide the luxury of a smooth steady idle.

What sort of electronic ignition dizzy have you got ?  Is it one of the 5K Toyota ones, or an aftermarket electronic module inside a 3K or 4K dizzy, that simply replaces the points ?

We can certainly assist you, but a few pics posted here of your setup, including inside & outside the dizzy, & any vacuum lines to the Webbers & manifold, would help.

A picture usually tells more than a thousand words. More pics, & more details, the answer will be easier, & quicker will be to you sorting this out.

P.S.  Any idea what the grind on the lumpy cams are ?  Is it a 4K engine block ?

Cheers Banjo

[altezzaclub]

Take the dizzy out, turn it one tooth and put it back in.  One way or the other will get you in the 10deg timing range, and even if you turn it two teeth it won't worry it. Just play with it until you get it where you want it.

While you have the cap off the dizzy, suck on the vac advance tube and make sure the dizzy base plate turns. If its jammed it is likely rust under the base plate where there are three ball-bearings it rotates on.  Maybe your electronic setup runs on a different method, but it should rotate under vacuum.

Make yourself a series of timing marks with whiteout correction pen around the crank pulley. When you have the motor running check the advance against it every 500rpm and generate a timing curve.  That curve is generated by the centrifugal weights under the baseplate, and that's the ignition advance that is important. I've got a topic about it here-

Most race cars disconnect the vac advance with Webers. The vac advance is just to advance the timing advance at cruise speeds for emission purposes, the moment you open the throttle to overtake someone it retards back to the centrifugal weight's setting, and then when you lift off and cruise again the vac advance sucks the timing up a few degrees to make sure the burn is better in a lean cylinder. So just disconnect it and see how you go.

4Ks can run with a lot more than the factory advance, they seem quite resistant to pinking, but too much advance does cost power. The whole reason for it is that flame propagation in the cylinder takes place at a constant speed, so to get the fuel burnt before the exhaust valve opens you have to light the fire earlier as piston speed goes up. Obviously from this it depends on compression, throttle opening, points gap, fuel octane, cam timing...  there is no 'right' answer between different motors.

 

It sounds like a fun motor! Can you balance the Webers yourself? Its not hard once you know the tricks.