im finally starting to work on an extra set of heads i have and i was wondering if this will be good.. so far im just rounding off all the lines and edges inside the intake ports to smooth the flow and i was wondering how much to actually port it?? i know porting to much will hurt the performance..

stock intake port=26mm wide
82mm tall,

so i was think porting 2mm on the perimeter to = 30mm wide
86mm tall

to much? to little??

 

Did this work? Wanting to port and polish my truck heads as well

 

i wouldnt go too much. i think you are in the correct range. but i would definately spend some time smoothing it all out. ive seen 15rwhp gains throughout the rpm range from guys who only smoother out the heads. good luck

 

Well "Turbo" you just made up my mind on what I am going to do to my heads. What about milling them down some. I have seen guys on here mill them from .015 to .040. What is the magic number? How much more performance do you guys get from milling the heads down?

 

I think the most common is .030. I have a set of 862's at the house that will get that as soon as I get the money.

 

Hey "Red" do you have to shorten your pushrods when you mill the heads down? I am about to install a TR224 Cam and have hardened .740 pushrods.

 

there is no magic number when milling heads, it all depends on what the combustion chamber size is on the heads you start with and what compression you want to end up with. more compression=more power but there are TONS of variables to think about also. if you have forced induction (super charger or turbo) you dont want to go over about 9:1 compression ratio. if you are naturally aspirated it all depends on what your intended use of the vehicle is and what supporting mods you have to go with the compression ratio.

and yes you need shorter pushrods when you mill the heads...get a pushrod length checker and measure to see exactly what length pushrods you need

 

Well, I guess the bigger question would be, is it worth cleaning up the heads and milling them with a TR224 cam and will have a built trans with a 3000 converter, 3:73 gears in a 72 pickup that I want to drive daily but still have a little fun with it? I am a do it yourself kind of guy so I can learn different things and wanted to give it a try and clean up the heads, mill them and see what it does. Opinions?

 

After milling my heads i ordered 30k Rocker shims from crane and they work great, I think i paid around $25.00, I've had no problems w/ them at all...

 

I am porting my 317s at the moment and I am going a little bit more than just 2mm, but this is the second set that I am doing, so I am getting ballsy. I am monitoring the port size through 7 different measurements in the port, going for a 15 to 20% increase in volume overall, while trying to retain some shape...hopefully I don't ruin them.