Gallileo60

Have a question, or 2, or 3 on 305 heads...What is a safe amount to mill the heads on a 89 code "E" TBI 305 for a increase in compression??? How do you figure the compression increase from a amount of milling??? Also, how much must be taken off the intake face to keep the intake fitting properly??? Anyone done this on a TBI 305??? I know these heads blow, and all, but lets just say these are theoretical questions........Thanks, Tom

Sonix

iTrader: (1)

Groan.

Ok, approximate the area of the chamber that's at the face. Then calculate the volume, then back calculate how many thou's equal a certain amount of volume. It's tricky to get the area of the chamber at the face, since it's a weird shape, you might be able to get a reasonable guess, but maybe someone has already done this and can say for sure.

Why is this such a popular question to ask anyway? Is the world filled with useless machinists? Or are you going to do this yourself with your giant milling machine in your garage?? I'd make my machinist earn his $100/hr, and say "make these heads 54cc", if he asked any questions i'd tell him "hey buddy, that's your job, just make it happen".

Usually the same amount needs to be taken off the intake, but if you only mill a bit, then you can just leave it as is. There isn't much you'd really want to mill from 305 heads right? So you probably won't need to mill the intake face.
I'm not going to insult you for wanting to re-do your 305 TBI heads (i'll do that later ) But I mainly want to know why you want to mill 305 heads? They have small chambers already..?

Gallileo60

Hey Sonix,
Thanks for your reply.....As I said it was a theoretical question....I remember back when I did my Dodge heads(1980's) we had to take some off the intake face, because we took a good amount off the chamber side....I did entertain the thought of going for a little more compression while I had the motor apart...Doing a cam change...I was not going to redo the heads tho....Anyway, once again, thank you, Tom