i just bought a used stock '98 banshee head claimed to be milled .30 from some guy half way across the country from me.

well, i looked at it and, you know the domes (2 circles), well you know that "ridge" that goes around the domes (like a ledge)? and then the rest of the head is the same height as that ridge or ledge(where the gasket touches) well on the left side (right side when bolted on to cylinders), 1/4 of the side of the dome, the ledge is more smaller (milled down more) and it almost flush, making it look and feel almost as there is no "ledge" there.only a very small and slight ledge is left. the rest has alittle "ledge" sticking up, as does the right side.

will this work without any problems? will it leak? will i have detonation? should i have this fixed or just trash it? i would rather waste the 40 i paid for it then the 350 it would cost to have my topend done? thanks for your help.

i hope it will work. and if it wont, what can i do, have it remilled? but if i do that wont i have gone to far to run on 93 pump gas?

thanks again

 

i found out the answer from the guy i bought it from....... thank god.

it should have the same volume in both sides the ridge may or may not match. when they mill a head the whole perpose is to equall the volume and up the compression in each cylinder. it will normally true much more acurate than a factory un milled head.

 

always glad to help

 

I'm not to sure I get what your saying. I plan on milling my head in my machine shop at work. How you would do this would be to set the head up in the vise and indicated it in so that it perfectly even, then mill the 0.030 off the gasket surface. Both chambers should look identicle or the same. One way to find out if yours is uneven is to CC your head.

Mac

 

For all of you planning on milling the head, do yourself a favor and do these two simple things.

First, get a pair of calipers and measure the thickness of the head at the head bolt holes in several places. The head bolt holes are all cut to the same distance from the head surface. They should all be roughly the same, +/- 0.0010 inches. Right the numbers down, and after the shop mills the head, remeasure it in the same places. If they do it right, then the difference should be what you asked them to mill it. Mine was slightly angled after I got it back from the shop. It was off 0.001" from one side to the other. It didn't make a difference. Ther was negligible compression difference.

Also, you should cc your heads with a syringe and ATF before and after the milling. Cutting the heads 0.040" should get you to 20 cc's.

To cc the heads, lightly clamp the head to a smooth surface, like a piece of glass, and fill the chambers through the plug hole until the ATF comes up to the plug hole threads. Don't fill it to the top, just cover a thread or two. Whatever you put in is the head volume.

If you do this before you get the head milled, you should let the shop know, so that they know they are being checked. Any good shop won't care, and any bad shop will do a more careful job.

Lastly, on a motor with stock porting, don't go lower than 20 cc's unless you want to make less power...

 

Explain to me how milling the head more than 0.040 will give you less power??

Also when cc'ing the heads you shouldnt fill them up to a few threads as you measuring the volume of the chamber not the plg hole.

Mac

 

Sandman, Do you need to run higher gas than 93 octane? What elevation do you ride at? I live in Chicago where the elevation is between 600-700ft. I don't want to have to run higher than pump gas.

 

I am not sure I agree with the guy you bought it from. If the head has been milled unevenly you will have higher compression on one side than the other. Also if sufficient space was not left you will have piston slap on that side. Personally I would try to have a proffessional check the head and if its not salvageable JUNK IT. Its not worth ruining a motor over...