How do I change the valve rockers? M20

[nando]

Don't think I'm getting this right. Is the shaft going to be pushed towards the radiator or the firewall?

I'm only going to chance cyl nr 1 rocker.

it really should be pulled forward towards the radiator.. you could do it the other way but I don't know if there is enough room.

btw it is easier off the car of course. for fun I took apart my old head to see how fast I could do it, took about 10 minutes with a 10mm wrench (to remove the eccentrics for clearance) and a flathead screwdriver. no hammer at all.

[Syncro325is]

no, they are held in with a key at the front of the head. they are not an interference fit.

You're right, I forgot about the key...
But just because the shafts do not come out easy does not mean that they are bent. Its a tight fit.

[Mr. Horsepower]

Looks like I just have to fit my S14 into it :P

Problem is that I have to use the car every day to work...!

If I just could push the shaft far enough against the firewall to get the rocker out. What is the key you are talking about?

[Syncro325is]

[Mr. Horsepower]

Have you posted a pic?


Now I have got one rocker out of the part engine, and it seems to me that I have to pull the head of on the other engine :( The rocker shaft, should it not be pulled out easily?
If I was going to get this one anywhere I had to hammer it!

[Syncro325is]

yes i posted a picture. its showing up for me... heres the link: https://80-75-156-107.colo.gravityin.../M20head-4.jpg

On a cylinder head that has not been taken apart recently the rocker shaft is going to be hard to pull out. Did you remove the key yet? (picture link i posted)

[nando]

yes i posted a picture. its showing up for me... heres the link: https://80-75-156-107.colo.gravityin.../M20head-4.jpg

On a cylinder head that has not been taken apart recently the rocker shaft is going to be hard to pull out. Did you remove the key yet? (picture link i posted)

mine was 185,000 miles, untouched. it came apart easily, and it wasn't the first one I've done. It wasn't even clean, this motor had oil/coolant mix for almost 20,000 miles. yuck! 8)

[ZombiE30]

Wouldn't it make sense for there to be a fair amount of resistance to movement in the rocker rod?
Otherwise, it seems like it would slowly begin to rotate while operating, which would put the oil paths out of alignment.
I mean, it wasn't super hard, but I'm glad it was out of the car and it was pretty reluctant until I got it halfway. Then I just pulled it.

It's also in the realm of possibility that my head sucks.
Damnit! Now I'm worried about that!
How do I tell if the head is warped?

[nando]

NO, because the key holds them in place! if you built the head and left out the key, the rockershafts WOULD rotate and you'd destroy your head. Just as Ranger Gress..

[ZombiE30]

oh, that makes sense.

....and nevermind about the head-warp issue, I'll just pester my Engine Assembly teacher when the semester starts in a couple weeks. He's gonna be real tired of M20s by the time I'm done with him....

And hopefully when all the internals are done getting sandblasted/steamed.....everything will just slide back in like it's supposed to.

(back on topic)
OP: basically you could do it either way. If it's your first time messing with that stuff, it would be a lot easier out of the car. And getting the head itself out is really not a big deal (provided you have torx sockets) though it will require a replacement head gasket and head bolts. The hardest part is getting the intake manifold off, just because of the bolt placement. You could also try pushing it towards the firewall and you might get just enough clearance to get that one rocker out. I have never tried that. You could try measuring the clearance vs distance required first, and see if it even seems plausible.
Your car=your call.
Good luck!

[Mr. Horsepower]

I have now detached the head cover, radiator and timingbelt cover. There is no chance to get the shaft backwards to the firewall to get out just one rocket I think. The timing belt was not tight at all, it had loads of slack!

There is possible to remove the head with the intake mounted on, so that I'm not worried about. I most worried about finding the marks for the timing belt again when putting it together.

Do I have to remove the fan to change alternator-, servo and timing belt?

The key I found before seeing the picture!

[ZombiE30]

yes, you have to remove the fan to do the alternator belt (and it makes everything easier).
also remember that it is a reverse thread, so to get it off, you have to turn the nut clockwise.

[StereoInstaller1]

BTW, it is easier to remove and re-install the windshield than it is to remove the head.

[kishg]

FYI: the rocker shaft will not just "come out" or "slide out".
It's a pretty snug fit, and I had to use a drift and a BFH to get mine out. (With the head out of the car, on my kitchen table).
You may want to keep that in mind if you're trying to do it in the car. (ie much smaller clearances)

+1

take head off and do it.. it's not that bad.

[Mr. Horsepower]

BTW, it is easier to remove and re-install the windshield than it is to remove the head.

Now that is obvious! To get the windshield out of the gasket is not difficult at all. Is is not difficult to remove a head eater, just a lot of work and many things to remove. Hope I get the head off today.