Ke70, missfireing only when engine warms up

[MarkIIRx12]

Hi again

I went over the dizzy, checked the point clearance on all 4 lobes, put on new dizzycap and rotor, fired it up and still the same crap.

I took a flashlight and looked closely at the inletmanifoild gasket, i could see something looked like tiny cracks. Bought a can of crc/565 with a tiny straw thingy on and put that directly into the cracks. The engines rpm changed a lot, on every cylinder as i did it on all 4 inlets. So i will have to pull the manifoilds off and change the gasket.

Since i have to take the manifoilds off anyway, i will take the head off, shave the head and get a overhual set. I also think i will get new valve springs, since this engine doesnt rev very well compared to the other 3k and 4ks i have had.

should i just go for new toyota valve springs? or maybe insert a spacer/washer underneat the old onces? or buy stiffer ones? if stiffer ones, where can i get them?

Thanks again for all ur help, i wouldnt have figured out or looked the cracks in the gasket if it wasnt for ur suggestions about lose manifoild and stuff

[toyboyracer]

Sucking air through through the inlet gasket would upset your mixture and ALSO upset its revving and power.
Might need to redo the mixture after replacing the gasket.
Next step is to take off all the ground/earth wires/straps, sand where they contact as well as their ends
and reattach with star washers.

Is the engine set at 10 - 12 degrees advance ?

If say it's on 0 - 5 it would be a lot less responsive than your previous motors.

Before just ripping the head off, do a compression test - Always do that before so that you have a base line
to compare with

[MarkIIRx12]

Thanks for ur answer.

I already sanded most of the leds/earths and stuff, cept the main earth to the engine, i will do that too tho.

I havent checked the timing yet since the previous owner said he had the carb and ignition set at toyota just a lil while before he parked the car, and now the car been sitting for many years, but i figured just leave it like it is yet until i get the leak fixed.

Only thing about ripping the head off now is since i already have to take the manifoilds off and thats like half the work, so im considering just getting the head done at the same time, but like u say, the engine prolly gonna rev a lot better and have more power when i get the airleak fixed.

anyhow, i guess it wont hurt to stiffen up the valve springs, does anyone know how thick washers/spacers i can safely use to stiffen up the springs? i just looked at toyotas stock springs and they were kinda expensive. do i put the spacers on top of the spring under the valve cap thingy?

Compression test i really need to do, just need to borrow one from a friend first.

Thanks again for all ur answers

[toyboyracer]

Springs off a 5K head may presumably be of stiffer value?

[ian]

another way to check leads etc
is start it up in total darkness and have a close look at the leads and around the dizzy cap also at the coil you may see fine blue sparks , also slightly offtune the car radio and listen for ignition crackle through it , that gives an indication whether its mechanical or electrical
ian

[allencr]

I also think i will get new valve springs, since this engine doesnt rev very well compared to the other 3k and 4ks i have had.

should i just go for new toyota valve springs? or maybe insert a spacer/washer underneat the old onces? or buy stiffer ones? if stiffer ones, where can i get them?

anyhow, i guess it wont hurt to stiffen up the valve springs, does anyone know how thick washers/spacers i can safely use to stiffen up the springs? i just looked at toyotas stock springs and they were kinda expensive. do i put the spacers on top of the spring under the valve cap thingy?

I haven't read anything that would suggest springs are needed. Why, it's not the 'doesn't rev very well'?
What's the compression & age & mileage/kilometerage & modifications????????
************
************
Also, if it runs well when cold with those intake leaks, its gotta be way rich.

[MarkIIRx12]

Hi again

Today i changed the manifoild gaskets and adjusted the valve clearance. Now the engines runs fine, not even a single missfire, so that part is finally over. Thanks to everyone for ur help, a round of + rep is on me

Im still not completely happy with the rpms this engine gives me, it has pretty good torque from the buttom wich actually suprised me (good compression im sure), but at the top it doesnt have anything at all.

Not sure what u call this in english, but directly translated from Norwegian it would be something like valve floating? i dont know if u understand what i mean by that.

I dont know at what rpms the engine/valves starts "floating" since i dont have a rpm gauge, but im guessing around 6-6500rpms, maybe even lower.

The rear axle and everything is stock, if i really push the engine i get like 80km/h in 2nd gear, im pretty sure i remember my other ke70 did easily 90 on 2nd gear, this one is really slow and painfull to get up to 80.

This is one reason i think i need to stiffen up the valve springs. What do u guys think?

Everything on my car is stock, never been modified, driven by a old farmer since it was new. He got the engine changed from the original 4k to this 3k wich supposedly came outa a starlet, but so far i dont know what kinda 3k it is.

Thanks again for ur help

[Scoobzd]

Valve bounce / valve float

http://en.wikipedia.org/wiki/Valve_float

And yes we are a helpful lot

[lexsmaz]

Check that you are actually getting mechanical advance from the distributor, as that will cause very sluggish acceleration further up the rev range if its not working ... To check disconnect the vacuum advance if it has one & rev up the motor & use a timing light to make sure the timing does advance ( & the correct amount too ) its not uncommon for the dizzy to seize up the advance weights etc, on some old motors ..

Also you can take off the dizzy cap & try & turn the rotor button in the direction of the shaft rotation, it should turn some degrees & then when released come back to where it started from ..

[TheToyman75]

MarkIIRx12,

If the engine is stock you are not only wasting your money but REDUCING performance by putting in stiffer valve springs. The stiffer the spring, the more power gets consumed compressing them, and hence the less power you have at the wheels.

Its a K Series engine, the factory cam is designed to have power at lower RPM, its SUPPOSED to be gutless at higher RPM as the factory cam is well out of its efficiency range, here is an idea for you.... Change gears

If you want it to rev harder for longer, get a mild cam grind.

[Scoobzd]

When Dad sets up rocker clearances he doesn't go for the "0" tolerance gap.

Ever so slight amount of clearance is what he aims aims for because valves are always
seating themselves firmer with every closed action n its better to have them open a few
thou' less than not having them closed properly. As time goes by the valve will naturally
close its own gp between the valve stem n the rocker.

So say you messed up with your clearances, you may have a number of valves not closing
all the way n that will cause loss of power n sluggish revving.

Compression test, then adjust, then compression test

Hope thats of help Mark

[river]

Hi,

Ever so slight amount of clearance is what he aims aims for because valves are always seating themselves firmer with every closed action n its better to have them open a few thou' less than not having them closed properly. As time goes by the valve will naturally close its own gp between the valve stem n the rocker.

So say you messed up with your clearances, you may have a number of valves not closing
all the way n that will cause loss of power n sluggish revving.

I don't get this. What you are saying is you don't set the valve clearance to factory specs, but set them a fraction more (ie open), as the valves will eventually close themselves?

How long does it take the valves to close themselves?

How do the valves close themselves? Is it through wear and tear? And, until the valves close themselves, they must be open a tad, which means the engine is not running at optimal performance?

As mentioned, maybe I am interpreting what you're saying as something else, and hope you can enlighten me.

seeyuzz
river

[MarkIIRx12]

Thanks again for all ur answers.

Maybe u reduce the engines power a tiny bit by stiffer springs, but lets say the stock springs are soft, wich its pretty normal after 30 years and maybe 150-200 000 km, u will get valve float at a lower rpm than with a stiffer spring. my other corollas with k engines has been very willing to rev high, but maybe i just been lucky with those engines. I dont expect the engine to get top power like a twincam engine, i just dont want it to start floating at a lower rpm than they would do stock. Anyone know how high u can rev a stock 3-4k by the way?

Im gonna check the timing and timing advancer and set it perfectly within the next days, i will also do a compression test and adjust the carb since i got all the stuff i need for those things today.

3K engines has a pretty big valve clearance, so it shouldnt be a problem with them closing, the clearance is 0,20 and 0,30 so its pretty big gaps.

I hope and expect the car will run much better after i get the timing and carb set perfectly.

I will come back with the compression results and how it turned out when i get everything adjusted.

Thanks again for all ur help, and keep throwing in ur thoughts adn suggestions

A lil off the thread topic, but im hooking up a relay to get driving lights to go on when i switch on the ignition, does anyone know if i hook it up to the main headlight, will the park lights also go on or do they go on separete wires? like will i have to wite both park and head to the relay or just head?

Im also looking for a mid console thats a lil more fancy than the ke70 one, it will need to fit without major modifications, like about the same length from the gear stick to the handbrake, does anyone know if theres another car i can take the console from, like carina, camry etc etc? I have a mazda midt console that fits pretty good, but i rather not bring bad luck to this car with putting in any mazda parts

[MarkIIRx12]

Hi,



I don't get this. What you are saying is you don't set the valve clearance to factory specs, but set them a fraction more (ie open), as the valves will eventually close themselves?

How long does it take the valves to close themselves?

How do the valves close themselves? Is it through wear and tear? And, until the valves close themselves, they must be open a tad, which means the engine is not running at optimal performance?

As mentioned, maybe I am interpreting what you're saying as something else, and hope you can enlighten me.

seeyuzz
river

I think he might be thinking of hydrualic lifters, wich in my opionion too is safer to relase the pressure to get a bigger gap and they will close them selves to the right clearancer as soon as the pressure builds back up.

[Scoobzd]

I guess it relates to who would want to buy a NEW car with a slightly rattly motor ? LOL

And I'd rather have the valves fully closed than slightly open but its all horses for courses
in the end. About every 20,000k seems to be an adjustment time River

Done right = no rattle . Done wrong = valves not closing.

Done Dads way n theres less chance of a boo boo