DTL504

iTrader: (1)

I call the machine shop and they wanted $450.00 to port and polish these heads that I have on a 283. I was not about to spend that much money on a engine that I will only use until next spring.
Well I took a liitle time this week end and done the port and polishing job on the heads. Check out the picture and let me know what you think. I could not get all the way in the intake runner but I got plenty of it.
Here is some before and after pictures.
http://f1.pg.photos.yahoo.com/ph/dtl...r=/461%20heads

a73camaro

It appears that you did not gasket match the ports.

Sitting Bull

I think it looks pretty good! Congratulations--you'll feel a real difference once they're buttoned onto the engine

radiateu2

You probably could have taken more out of the intake runners. I agree that it appears that you didnot gasket match your porting work.

formularpm

As long as the head port is bigger than the intake port, gasket matching doesnt yield much if any of a gain. The heads look good, looks like the bowls/valve throats have been worked more than the runners. Many times the runners arent a restriction, removing material from them often adds a lot to port volume while contributing little or nothing to the flow potential.

radiateu2

I was actually referring to the exhaust ports. Most of the gains will be made by opening up the restrictive exhaust ports. Gasket matching is mostly important here since the gasket will become the restriction causing turbulance in the exhaust pattern. The most restrictive part of these heads are the small narrow exhaust ports. I agree that more can be gained by opening the exhaust ports is more beneficial than opening the intake side. On the intake side turbulance is a good thing it keeps the air and fuel mixed and atomized. Thats why we dont polish the intake side only the exhaust. On the intake side unshrouding the valves is more beneficial than cleaning out the runners. Valve shrouding in my opinion is the biggest bottle neck on the intake side.

AJ_92RS

Don't try to hog out the exhaust ports either. That's not the way to make them flow well.

The trick is to concentrate on the high side of the port, smooth and blend the valve guide, and very lightly smooth the short side radius.

You can bring the roof of the port up a little, but try and keep it a smooth radius.

Don't think you'll gain a lot from grinding a lot off the short side because you won't. There's a dead flow pattern there and you want to keep it that way. If you make it flow too well it can cause the exhaust flow to come off that short side so fast, it will literally crash into the high side and cause turbulance. Not good. :nono:

Like the intake side, it's OK to have the exhaust port coming out of the heads a little smaller than the header tubes/manifold ports especially on the low/short side. It helps prevent reversion, which can also cause turbulence, poor mixture at low RPMs, and other things.

It actually looks like you're on the right path. It looks good.

Next set you do, try to get rid of the flat spot on the roof of the exhaust port where the valve guide sits up against it.

Try to make it look a little more like this.

formularpm

People have actually had gains in exhaust flow by making the short side radius flat perpendicular to the valve seat, might be something to try as well.

MrDude_1

i just thought you or anyone else browsing thru there might want to look at this..

its kind of a beginners how to on porting.. http://www.sa-motorsports.com/portdiy/diyport.pdf

ShiftyCapone

iTrader: (7)

That is a great link. I have been searching for awhile for a great DIY porting guide. Thanks for the heads up MrDude.

AJ_92RS

Would those be professionals, with access to flow benches and dynos?

ShiftyCapone

iTrader: (7)

I would say yes. But not necessarily professionals. From I read all the time small block heads typically are really restrictive on the exhaust side and can improve dramatically from just the simplest port job.

formularpm

If you consider David Vizard a professional, then yes.

AJ_92RS

A-B conversation...

Exactly my point.

Unless you have access to a flow bench and dyno, don't mess where you don't now exactly what the results will be.

formularpm

Thats probably the best advice you could give a novice porter. Id add a velocity probe to the list of essential tools, though.

DTL504

iTrader: (1)

Here is a few more articles that I read:


http://www.ws6transam.org/ported.html

http://www.babcox.com/editorial/us/us110128.htm