Setting timing on KE70 corolla (4K) help?

[Big_Valven]

Non Holden question I know, but there are plenty of knowledgable people on here so I thought I'd ask.
I'm trying to set the timing properly on my 4K (not hi cam, KE70 though.) I have had issues with it backfiring into the carby and a lack of power at low RPM.

I haven't done it before but I roughly understand the process. Timing light on cylinder 1 (front cyl,) timing should be around 8 deg as indicated with vacuum advance line disconnected from distributor.

When I first connected the timing light, it indicated at least 30 degrees!? I loosened the distributor but as I adjust it back towards 8 degrees, the engine starts to hesitate and eventually stalls. Even back near 20 deg, the engine will idle but hesitate badly as I try to free rev it. I have tried adjusting idle control which helps the idle, but obviously still hesitates when I try to rev it.

I have just put it back to a point where it will free rev properly, but it still seems to be around 30 deg. It is running better at low revs now though so it must be set a few degrees differently now.

If anyone can think of anything I'm doing wrong or anything else I can try, let me know. :)

[the big fist]

are you blocking off the vacuum hose after you disconnect it from the dizzy ?
Haven't used my light in a while but pretty sure the tube has to be blocked or else you get a nice big vacuum leak.

[Big_Valven]

Ah that would explain some things. Thanks for helping out a n00b. I'm not sure if that will fix things entirely but it will help.

Any other advice is also welcome :)

[the big fist]

I am far from super knowledgeable on older cars, but know enough to get by. Try googling for some info on setting the timing on your car. Pretty important that your points are set properly (if it has points). Things like new condensor help, plug condition etc. Your dizzy hasnt been removed and put back in 180deg out ?

I moved to electronic ignition as points gave me too many dramas. From memory I also had to increase the idle speed on the carb, get timing right, then drop idle back down.

[whitels1ss]

Non Holden question I know, but there are plenty of knowledgable people on here so I thought I'd ask.
I'm trying to set the timing properly on my 4K (not hi cam, KE70 though.) I have had issues with it backfiring into the carby and a lack of power at low RPM.

I haven't done it before but I roughly understand the process. Timing light on cylinder 1 (front cyl,) timing should be around 8 deg as indicated with vacuum advance line disconnected from distributor.

When I first connected the timing light, it indicated at least 30 degrees!? I loosened the distributor but as I adjust it back towards 8 degrees, the engine starts to hesitate and eventually stalls. Even back near 20 deg, the engine will idle but hesitate badly as I try to free rev it. I have tried adjusting idle control which helps the idle, but obviously still hesitates when I try to rev it.

I have just put it back to a point where it will free rev properly, but it still seems to be around 30 deg. It is running better at low revs now though so it must be set a few degrees differently now.

If anyone can think of anything I'm doing wrong or anything else I can try, let me know. :)

Sometimes the outside of the harmonic balancer slips (worn out or loose damper rubber) and the timing mark is out of whack and shows a wrong reading for top dead centre.
I have had this a couple of times before, it could be your problem.

[SS Enforcer]

OR ... the timing belt has slipped a tooth or two which happened to my Mothers old Corolla.

cheers

[mmciau]

OR ... the timing belt has slipped a tooth or two which happened to my Mothers old Corolla.

cheers

AHHHH!!! I think you would be close to touching valves and pistons with that amount of belt tooth loss


mike

[whitels1ss]

OR ... the timing belt has slipped a tooth or two which happened to my Mothers old Corolla.

cheers

Yeah I did not read properly enough the orig post about problem backfiring in first place, belt could also have slipped as SS Enforcer says .....or another possible is those early electronic distributors had a reluctor wheel which was supposed to stay in place on the distributor shaft with a keyway which sometimes wore and let the reluctor wheel move on the shaft making the thing fire at the wrong time. (This was fairly common on late 1970's early 1980's V8 Fords.)
But I reckon SS Enforcer's idea would be my best bet. :goodjob:
Just another idea to look at!
Hope you find it easy mate.

[whitels1ss]

AHHHH!!! I think you would be close to touching valves and pistons with that amount of belt tooth loss


mike

Some will still run 1 tooth out without touching.
The old Laser 1.6 litre Mazda motor was one which would never touch, I had a belt let go on me years ago and they fixed it for me so easy and quick! :goodjob:

[SS Enforcer]

AHHHH!!! I think you would be close to touching valves and pistons with that amount of belt tooth loss


mike

My mums old car did slip a tooth and run .... very poorly though.

[10sec_rx7]

4k has a chain not a belt, its a push rod motor..

you need to set the points before setting the timing, if the points gap is not correct then you wont be able to set the timing correctly, if they havent been touched in a long time they will probably need replacing..

from memory about 35tho is around the gap they should be..
a good condition 4K will run best at around 12deg timing.

[LS1-5.7]

Check that there is no play in the base plate or shaft of the dizzy and your timing isn't affected. Statically time the motor first by winding the motor over by hand to no 1 firing stroke at the required timing mark on the harmonic balancer, eg 10 Deg BTDC. Then turn the dizzy (with cap off and ignition on) against the direction of rotation of the rotor button and when the points fire you know you've got approx 10 deg BTDC. Point gap & dwell have to be set first off course :)

[Big_Valven]

Yep it's a pushrod engine, timing chain, no harmonic balancer, only a crank pulley. Points and dizzy cap are fairly new. Would be misfiring quite badly if dizzy was hooked up 180 deg out? (cap doesn't fit on both ways anyway.)

LS1-5.7 - I tried this method today, albeit with a multimeter on continuity mode, but the same idea.

The rotor in the dizzy is about 30 deg off #1 when the timing mark on the pulley is lined up with 8 deg marking on the block. The engine runs brilliantly when the dizzy is simply adjusted for the engine to rev freely, heaps of punch, I suspect that a slipped timing chain or severely wrong timing would affect drivability otherwise. So I think that the crank pulley is simply not indicating the correct timing for one reason or another.

I'll get some help from a friend next time I have the opportunity (it's a weekend slider) but until then it's not pinging and it's running like a champ. So we'll see how it goes.

[Phonic]

Deff check the points, rotor and dizzy cap and replace if needed.

If you're sick of adjusting the points all the time, convert it to electronic dizzy. You can get electronic dizzies for these out of some 5Ks (1.5L), or easier to find 7Ks (1.8L) (out of late model Townace vans, some even had EFI!!!)

I did the full 7K-C conversion in a 2 door KE30 Sedan, set and forget with the electronic setup.

[ccclv]

try taking out #1 spark plug and insert a screw driver (or make up an extention on the end of an old sparkplug) down in to the plug hole then wind the engine oner carefully till the piston touches the screwdriver in the cyl make a mark on the ballancer then wind the crank over the other way till it stops again on the object in the cylinder and make another mark on the ballancer then just measure and make a mark between the 2 marks you have put on the ballancer and you have the true top dead cente.

another simple trick is to stick your finger over #1 plug hole and wind the engine over by hand, you will feel as it is comming up on the compression stroke and as soon as the piston is up the top, theres #1 tdc ready to fire