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-   -   99 mazda miata, Hard to start, shaken engine after head gasket replacement ~! (https://www.miataturbo.net/engine-performance-56/99-mazda-miata-hard-start-shaken-engine-after-head-gasket-replacement-%7E-66373/)

flounder 06-10-2012 09:06 PM

I would take both of them to a machine shop and see what they say. It's good that you have another set of shims, springs and valves to work with. I don't think it would cost more than $50 bucks to get both heads checked out, our local shop only charges me $20 for a head inspection.

The problem with having zero clearence between the cam and the tappet is that it's not allowing the valves to fully close and besides causing poor running condition, it's also not allowing the valves to cool properly by not allowing them to rest fully on the seats. Who knows what happened to this head before you got it, you know?

thomas18a 06-10-2012 10:10 PM

so i should take both head to a machine shop and ask for valve clearance?
Thanks for advices



Originally Posted by flounder (Post 888211)
I would take both of them to a machine shop and see what they say. It's good that you have another set of shims, springs and valves to work with. I don't think it would cost more than $50 bucks to get both heads checked out, our local shop only charges me $20 for a head inspection.

The problem with having zero clearence between the cam and the tappet is that it's not allowing the valves to fully close and besides causing poor running condition, it's also not allowing the valves to cool properly by not allowing them to rest fully on the seats. Who knows what happened to this head before you got it, you know?


Twibs415 06-11-2012 12:58 AM

you cant set the valve clearance properly with the head unbolted from the car. with that said. check the clearances and set them accordingly. if it still runs like crap after that do a compression test. if its low pull the head and pour water/brake kleen into the runners when the valves are closed. this will show you if you have a bent valve or not.

thomas18a 06-11-2012 01:10 AM

http://youtu.be/rmEtGkpg2SQ
this is how i checked the gap, but no luck, it cant fit the thinnest feeler


Originally Posted by Twibs415 (Post 888269)
you cant set the valve clearance properly with the head unbolted from the car. with that said. check the clearances and set them accordingly. if it still runs like crap after that do a compression test. if its low pull the head and pour water/brake kleen into the runners when the valves are closed. this will show you if you have a bent valve or not.


Twibs415 06-11-2012 01:13 AM

ok so its to tight. correct this first and see how goes it.

BogusSVO 06-11-2012 10:05 AM

I watched the vid... You used a .010.. thats a bit thick to start.. get a feeler gauge set that has .003, .005, .007

Also if the machinist or the engine builder was sharp, he may have set the lash up a bit tight so the cam wouls appere a tad larger.

So if you find .006 lash on the intake and as tight as .007/.008 on the exhaust it will be ok.

I say this since your .010 would not fit down either bank of pucks


And try again

Twibs.... what can you not set the lash with the head off the engine?
I must have been doing it wrong all these years.....

thomas18a 06-11-2012 01:52 PM

i bought the feeler guages from auto zone
http://www.autozone.com/autozone/acc...fier=1931_0_0_
the thinnest one is 0.010 254mm.
i am going to get something thinner tomorrow.



Originally Posted by BogusSVO (Post 888370)
I watched the vid... You used a .010.. thats a bit thick to start.. get a feeler gauge set that has .003, .005, .007

Also if the machinist or the engine builder was sharp, he may have set the lash up a bit tight so the cam wouls appere a tad larger.

So if you find .006 lash on the intake and as tight as .007/.008 on the exhaust it will be ok.

I say this since your .010 would not fit down either bank of pucks


And try again

Twibs.... what can you not set the lash with the head off the engine?
I must have been doing it wrong all these years.....


Twibs415 06-11-2012 08:40 PM

svo,



when you torque heads down there is some distortion and can change clearances. neither is wrong or right

BogusSVO 06-11-2012 09:00 PM

If when you torque the head, and it distorts enough to distort the cam towers to affect lash settings.... The head is junk beacuse at that point the cam journal oil clearance is gone, and the casting will grab the cam.

Twibs415 06-11-2012 09:19 PM

im sure it changes but to what degree. a few hundred thou? i dunno. but for all we know op didnt clean the block or head good when putting a new hg on. did he put a new hg on? and do the feeler gauges fit any of the lobes? it would be strange if all the valves were tighter than .254mm/.010in as the exhaust side should have more clearance than that.

BogusSVO 06-11-2012 09:27 PM

I have personally set exhaust lash tighter that .010, it can add a few degrees of duration and a tad more lift.

Since the op seems to have bought a built head, it would not be uncommon to find tighter than stock lash settings.

Now if he is .003 intake and .005 exhaust.. to me, thats a bit too tight.....

thomas18a 06-14-2012 09:31 PM


Originally Posted by BogusSVO (Post 888706)
I have personally set exhaust lash tighter that .010, it can add a few degrees of duration and a tad more lift.

Since the op seems to have bought a built head, it would not be uncommon to find tighter than stock lash settings.

Now if he is .003 intake and .005 exhaust.. to me, thats a bit too tight.....

sorry for the late update
finally i bought the right feeler gauges.
Below is the numbers that i got. Do they look right?
Intake: 0.06 / 0.07 / 0.07 / 0.09 / 0.07 / 0.08 / 0.08 / 0.08
Exhaust: 0.08 / 0.09 / 0.08 / 0.07 / 0.06 / 0.09 / 0.10 / 0.07
It looks like exhaust side is a bit too tight, right?

BogusSVO 06-15-2012 11:06 AM

Looks a bit tight, but should run, and not shake the fillings out of your teeth.

Now do a compression test, and a cylinder leak down test.


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