jeffro22

Ok, thanks, ANy idea on the cost of milling the GT-40's and what specs I give the machine shop to have them milled?

MBDiagMan

3/8 studs, 1.6 ratio.

paddy187

Thread hijack time,

I have 289 heads think they are orginal car i.e. 1965 and I have trouble adjusting the valve lash so is it the the studs coming out of the head? if so what is best way forward can I push the studs back in with a rubber hammer or something, or do I remove them and replace with new ones or is there any easy way for me to do a conversion to threaded studs? I don't have access to a machine shop so what is the best way forward?
Cheers

rmodel65

do you have adjustable rockers?? the rail type rockers arent adjustable you just tighten them down although they are on a stud style setup

paddy187

rmodel,

Not sure to be honest, I assume adjustable as I have overtighted before and stopped the cylinder working according to a mechanic. what is the best way to tell? Attached is picture that makes me think non-adjustable.

rmodel65

do the studs have a shoulder on them? the pic doesnt show a bare stud or the valve side of the rocker

rmodel65

heres a link to a pic of the tyoes of rockers arms the rail setup is on the right http://books.google.com/books?id=1TF...um=2&ct=result

Norm Peterson

If you mean that it won't hold a lash setting, either the studs are pulling out or the cam & lifters are going bad. Those are about the only places where extra lash will creep in at (though it is also possible at the pushrod/rocker and rocker/rocker ball surfaces).

If it is the studs, my advice is to go directly to screw-in studs (do not pass "GO", do not collect $200). It would take more than a rubber mallet to drive them back down anyway. Figure that the stud has to be still capable of resisting 200 lbs on the valve side plus 1.6*200 on the pushrod side and you're driving down against over 500 lbs total - not gonna happen with a hammer that "gives" at the surface it pounds with. Even if you got it done with a "real" hammer, you still have studs that will start backing out as soon as you turn the engine over, and they will probably back out faster than they did the first time.

How are you adjusting them? If they are hydraulics of any sort and you can't watch for pushrod seat movement relative to the lifter body it's not hard to keep "adjusting" - you're just driving the hydraulics' seats down and squeezing the oil out. Not like with solids where it comes up with a sudden and very obvious stop.


Norm

my77stang

jeffro, you'd wanna have a valve job on the gt40's anyways - and a valve job w/ resurface should be 200-250 bucks. you'd want them to knock at least .010 off the heads, .020 or even .030 would be better. you have to watch out about taking too much off, or you'll have trouble getting the intake to line up properly.

paddy187

Norm,

Yeah I was being dumb regarding the push in studs. I have adjusted them as per the FAQ and now going to try with a cut off valve cover and go by noise, unless better suggestions are forthcoming!! Rmodel mine are the rail type.