Thread: polish and port

Tweet

The first thing I will say is stay out of the valve seats.
To many people have given me heads that require a few new valve seats because someone has gotten to wild with the die grinder.
For cast iron you will need to invest in some carbide cutters.
They are a little expensive but should last you forever.
Then you will need a porting kit.
I would try Goodson for your porting supplies.
I would first remove all the parting lines and knock off any casting flash if there is any present.
Think radius/smooth.
No sharp turns of rough edges.
In a street car I would try and keep the finish in the 120/180 on the intake side to try and keep all the air/gas atomized.
The exhaust should be made very smooth.

thanks denny

You could check out your tools on some junk heads before going after the good stuff.

The technique uses a lot lighter pressure with Aluminum.....

well i have never worked with aluminum before but i have etched alot of glass and i have a pretty steady hand. figure that when i start it i get real confortable and take my time i should be okay.

i know about the gaskets but what do i use to scribe it with. they show what looks like a punch but do not tell me that they are using.

so by doing all this i should get a better burn of the air gas mixture?

so will this also help with any fuel that might excape through the exhaust. my car runs a little rich. if i dont run it that way it has a bad lope.

thank you denny for taking the time to inform me of all this. you are very kind. i am learning so much. you have made it very clear. i am the type that wants to try everything i read and do not some times think it out well enough. now if i can get my town to come off the zoning and building permit for my garage than i can get started.

yes you were very thorough. i really enjoy your drawings as it helps me see with my minds eye how things go if that makes sense.

gotta love a american made combustion engine.

Hi JYG, So far nobody has said "why". You want to match the ports to the manifold on the intake side and leave the intake ports in the head a little rough to maintain enough turbulence to keep the fuel droplets homogenized. The ports on the exhaust manifold should actually be a little larger than the exhaust ports of the head to provide a little ledge around the exhaust port to prevent "reversion" which is a slight tendency for exhaust gas to go back into the chamber. The exhaust ports in the head are where you want a smooth surface because the hot gases expand and need as much help getting out of there as possible. I know the theory, but paid $200 to have the exhaust ports smoothed out on my 350 "882" heads because it takes SKILL to do it right without holing through to the water chambers. I know the theory but don't have the skill so I paid a pro!

Best Wishes,
Don Shillady
Retired Scientist/teen rodder

they show what looks like a punch but do not tell me that they are using.

Sharpen an old screwdriver on a grinder and use it as a metal scribe.

they guy who does my heads buys new cutters for every set of heads.

When porting out heads the Bowl area or also called valve pockets . Is were the most HP gains are . But the ports still need to be worked for the full HP potential .