Hi all,

I have a set of 993 heads I am about to port and polish (any tips there greatly appreciated!) and then have a 3 angle valve job done. While it was in for the valves, I was considering getting the head milled (76cc chambers giving low compression). I have checked the archives here, and one post was made regarding milling these heads, stating that they could only be done a maximum of .005". Has anyone any experience of milling these heads, and can either confirm or refute that claim? I would like to mill them a safe amount, without risking anything.

Thanks for any help

Andrew

As for porting, you don`t want to do anything heavy, just smooth out the bowl under the valve, there`s a ridge left there, smooth it over, the valve guide boss, smooth it also. If this is your first time porting, that`s all I`d do. Try not to leave any pits anywhere while doing so, keep the cutter moving.
The 993 head can be milled more than you posted, these are heavy casted heads, although, I don`t really like to have heads milled unless I have no other choice. Depending on what you plan to do with your engine, to get a decent compression ratio with these heads on a street machine, I would have them milled .010, have the block decked .020, and a speed pro hyper coated skirt piston flat top with 2 valve relief. if you go this route, you`ll have to check the valve train geometry, as it`ll likely be out of whack. I would just get some small chambered heads.

those are heavy cast heads and will take the shaving that you are looking for but i think i would install them on your block with clay on top of your piston to see just how much you want to have cut off them and still be safe.also mr. gasket has a head gasket that is only .018" thick and is coated.i have a set of these heads and i took mine apart and took them to the machine shop and had them cut for 2.02/1.60 valves but have not had the chance to use them yet as i ended up getting a new set of iron bow ties.before i use them though i think i will have them cut .010-.020's".that and the big valve i'll bet will wake these heads up.i have a set of 462 camel humps i cut .030's" and still use them on the street so it should be ok.

i also have these heads on a 383 stroker with flat tops.. says my compression will be 9.6:1... is that high enough to use a cam with .520 gross lift?? also... i was thinking of using cranes h-11 tool springs.. they say they use the stock retainers and such.. they are stock diameter and can handle up to .600 lift... so would i still be able to enlarge my valves to 2.02"/1.06" or does spring O.D. have nothing to do with valve size?... does anyone know a decent kit that has springs.. retainers locks sealse valves all in one package?

The duration and especially leb sep will determine. If the lobe sep is 112 or higher it should be ok. 110 is pushing it as far as throttle response is concerned. Also a cam with 290 adv. duration is the absolute max. Too much spring for 520". you will lose power and have excessive lobe wear. Also cam breakin will be scary. spring seat diameter and valve diameter are not closely related. Comp K-kits.