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Topic: Milling GT40 heads (Read 4406 times) previous topic - next topic

Milling GT40 heads

Bothering you all again but as some of you heard I have a set of GT40 irons heads off a 97 explorer now I’m looking to mill them a little now I believe though ford says there motors are 9.1 compression I heard they really are 8.5..1 now I’m looking to go close to 10.1 compression w/out going over so ill be happy w/even just short of 9.5..1 so the question is how many thousands do I tell them to take off.
oyea pistons will be stock eyebrowed.

Milling GT40 heads

Reply #1 –
Quote from: Innes;115742
Bothering you all again but as some of you heard I have a set of GT40 irons heads off a 97 explorer now I’m looking to mill them a little now I believe though ford says there motors are 9.1 compression I heard they really are 8.5..1 now I’m looking to go close to 10.1 compression w/out going over so ill be happy w/even just short of 9.5..1 so the question is how many thousands do I tell them to take off.
oyea pistons will be stock eyebrowed.



stock eyebrowed meaning valve releafs..

and stop stressing

i don't think that motor would be 8.5to1 unless two things.. the heads where like 72cc which you can't get.. and two the pistons where TRW 2482 style..
see of you can read the ford number on top of the piston and post it and i will cross reffrence it

i forgot to ask which short block are you useing a HO or shop rebuilt?
anyway your compresion shoud be around 9.0to1

8.9 with 65.5cc heads, 9.0to9.1 give or take a tenth of a point with 63cc stock heads, about 9.2to9.3 with 60cc heads

now compresion allso depends on cubes i have a 306cid
and i use trw 2488F30 .030 over and with 60cc head i have about 9.6to1

now if i had standard bore pistons it would be about again 9.2to9.3

http://store.summitracing.com/egnsearch.asp?N=700+4294925232+4294839001+4294908331+401105+115+4294840126

i used to have the sheet that broke down all the pistons and their compresion ratio with what cc heads. i'll see if i can find it online

Nick
Quote
there's only about a half a dozen man made objects that are herd by the human ear below 40Hz,a pipe organ,thunder,the space shuttle lifting off,a jet airplane taking off or landing,a large canon,an atomic bomb ignited in your back yard and the heat wave afterward oh wait you would be dead so you would'nt hear it scratch that!,and maybe beating your hear against a wall less then 40 times a second..rap music is'nt one of them!thats 40-60Hz@100+db the moving air is under 40Hz

Milling GT40 heads

Reply #2 –
Brought the heads to a local speed/machine shop (Fulton Street Auto Parts) there in Farmingdale. For any one on Long Island I definitely recommend them they do outstanding motor work. Anyway they are going to mill them .010 he didn’t recommend more the .015 or I will have to start worrying about shimming the rocker arms and setting lash. He’s also going to check my valve springs in case they need to be replaced. I also gave him the GT40 upper and lower intake he’s going to sandblast it. It was looking pretty ugly/old.

Milling GT40 heads

Reply #3 –
Did a little research and my GT40 heads that came off a early 97 explorer I assumed the combustion chamber was 63.4-66.4 cause that’s what my book says but when I brought the to the machine shop he took the # off the and it was F3ZE-AA and the book states they belong to a cobra/HO/marine nothing about explorer. The # that belongs on explorer is F1ZE-AA. Though my book says my chamber size is 60.6-63.6 his said 62.1 so he milled off .010 and estimated I’m about 60.3.
Now I know he could of liquid filled them but he said its unnecessary besides my motor at this point is still together and there’s no way to get a real good compression ratio unless I do a piston to deck measurement.
Oh and I order a fel-pro head gasket @ .039 thick instead of stock.043. Again he estimated my compression to be 9.5.1 I actually contemplated taking another .010 off to try and bring it closer to 10.1 but I guess I could also get a thinner head gasket but then he said leave well enough alone since I don’t know exactly what I’m dealing with and every thing here is estimates.

Milling GT40 heads

Reply #4 –
Quote from: Innes;116969

Oh and I order a fel-pro head gasket @ .039 thick instead of stock.043.



i wouldnt do that if i were you

Milling GT40 heads

Reply #5 –
Quote from: jcassity;116986
i wouldnt do that if i were you


and why i ask

Milling GT40 heads

Reply #6 –
its probably one of my stupid gut feelings that a thinner head gasket couldnt be better ,,especialy when your hyped up on the performance drug.  Im probably wrong but imho i would stay stock or thicker just incase you decide larger valves are in your future or perhaps decking of the heads ect might be a later on issue with clearnce of the pistons.

Milling GT40 heads

Reply #7 –
That ant to bad you started scaring me for a second.

Hope you didn’t gincse me.