M20 head work questions...

[xLibelle]

having pulled this b25 head from a junker, im trying to pull it appart to have it cleaned up by a shop.

how do i get the valve guides out?
having looked at real oem, whats this valve seat ring shown?

well... thats all i need to know at the moment unless you have suggestions on service attention to the head and crank when i bring them in to be inspected and surfaces polished, etc.

[xLibelle]

lmao, i forgot ive never posted here... hello

[xLibelle]

ok, figured out the valve rings, couldnt see them under all the sut. basicly, dont harm these because i dont see these coming out.

but i still dont know how to get the valve guides out. ive taken a heavy hammer to them with no luck. leave them to the shop guy?

[rs4pro3]

Leave them to a shop, ussualy you have to heat the head and then press them out.

[Madhatter]

you cant remove them yourself. The head has to be heated and they are driven out, same thing to have new ones installed.

[xLibelle]

damn, price keeps on adding up.

im sure the shop will fill me in, but ill ask here anyway.
whats that called to have the head and crank checked for cracks? should i have that performed on the head for this stock rebuild?

i really only need this to last for a half season, but with being boosted ... and not knowing its history.

is hot tanking it necessary or just a good cleaning enough?

im new to engine work; any advice is welcome. :)


a certain spot on each lobe of the cam looks like a bit more than a polish is needed... if its at a reasonable cost to have them turned, since there will be a low boost blower involved, should i consider a change in the intake/exhaust overlap? any other thoughts here?

[xLibelle]

bump

[T.Dot E30]

Its called a pressure test for the head......donno what its called or if it can be done to a crank?
Before they pressure test it, they have to clean it up. I paid $75 to have one hot tanked and pressure tested, up here in Toronto

[xLibelle]

pressure testing is for the valves. this is something where the components are submerged in some chemical and coated and the cracks are visually accentuated and can then be welded and smoothed out. since this procedure hasnt gotten any real responce, then i think it not often performed

other procedues done is smoothing of rough spots where known weak areas are so that cracks have nothing to start from.


i found this about valve guide removal yesterday:

http://www.grmotorsports.com/board/viewtopic.php?t=12465

[joshh]

I had my E head rebuilt. Found a crack in it. It needed a new casing so the whole thing cost me $600.00. Now I'm going M50.:loco:

[88325isboy]

Take it to a shop and have them pull them out and have them put the new ones in.

[Jordan]

It's not worth doing valve guides yourself.

Also ANY TIME guides are replaced, a valve grind is needed. No way around this. No guide will ever press in perfectly in the same plane as the old one, and the valve will never seat/seal right.

[xLibelle]

i brought the head in today for guides and valve grind.

i suggested the heating the head and freezing guides ordeal to inquire about his procedure. the guy said that they dont like to freeze the guides because if they dont get it in quick, it makes it a lot harder to work with.
That makes sense. for example, if you want to boil water, you would start with cold water as it takes less time to reach boiling point with calm molecules then it is if you were to use warm water to begin with.
So a frozen guide might obtain heat at a rate which expands the guide more than "normal" and locks it into place after gaining heat from the head.

just a thought

[325Projectz]

if you want to boil water, you would start with cold water as it takes less time to reach boiling point with calm molecules then it is if you were to use warm water to begin with.

Holy shit, is that true?

But yeah, do the head rebuilt the right way.

[SA E30]

They X-Ray the crank, to check for cracks... well at least they do here, they also do it to cam shafts.