Well I finished up the port and polishing of my 081 heads. Everything went pretty smooth, and it wasn't actually as hard as I would have thought (for anyone out there that is thinking of doing this themselves and have never done it
I have all the pics up on my site so here is a direct link to the page...

Port and Polish Page

Give me feedback if you care to...

Later!
-Ben

 

did you knoe that your not soposted to polish the intake side, just exhaust, you want the intake to be rough because it keeps the air/fuel mixture mixed up and more dense.

 

IMO polishing the intake is completely harmless and
very benificial.
I couldn't get your link to work though.

 

Hummm Looks like a bowl blend job. Should not have polished the intake ports. I would have done more shaping and less polishing.

The valve guides can be shortened and slimmed quite a bit.
They stick out right into the high flow area of the roof of the port.

Should have bought some budget 1.94x 1.60 valves.
1.50" if the 305 still has the stock bore.
The port inlet opening can be squared up to match the stock
gasket and manifold.

The roof and the common port wall are high flow areas.
Raising the roof and straightening the common wall deep in the intake port will increase high lift flow.

 

Well, now you can evangelise everyone else on the board! Just follow F-Bird'88's advice and you will have done a nice job, and wasn't that easy???

 

This is a picture of a head that was removed for inspection
from a running engine.

The intake ports were polished on these heads.

See the clean part of the combustion chamber? That is where fuel was falling out of suspension and puddling back into a liquid.
(it sticks to the polished port walls) Separating from the air.
This reduces power and reduces gas mileage.
Liquid fuel does not burn.

Often professional engine builders will dimple the ports
and certain parts of the combustion chamber to ensure enough
"boundry layer effect" ( turbulence close to the port surface)
to ensure against this fuel separation from happening.

Smoother is not better when it comes to intake ports.

 

Well that's fine, but I simply do not believe that theory in its entirety. Fuel leaking into the manifold will do the same thing. Running a very large camshaft at low RPM (street driving) will do the same thing due to low vacuum in the ports.

Signs like you see in the combustion chamber shown are most likely from part-throttle driving & not from WOT operation. At part throttle, port vacuum should be high enough that fuel cannot exist in liquid form in the port. Low pressure drops the boiling point of, and vaporizes fuel. If the engine was run very cold and had poor vacuum in the ports, then fuel will drop out of suspension even if the walls are unpolished.
I would not always assume that a problem with fuel dropping out of suspension is directly caused by polished port walls.
IMO

 

87Formula4bbl,

Here is a pic of one carbide cutter that you can get which will let you reach those tough spots. It's only about $12 or so and leaves a very nice finish, as well, on the intake ports and bowls.

 

I know about polished intakes, I've read through so many posts on TGO about polished vs rough. I guess it's all a matter of opinion, not to knock anyone's expert advise or anything. I got help from both my mechanic, and a mechanic who builds professional pulling truck's. Both of them recommended polished intakes. The reason being: I went for the increased air velocity theory, instead of the atomization theory. Obviously, the faster air can flow into the chamber with less drag, the better. I disregarded the atomization theory because, the fuel is going to atomize no matter what. You are bringing a relatively colder charge (outside air mixed with fuel) into the ports. As soon as that charge hits the surface area of the hot ports (from engine temp), its going to atomize. So I think it's all a matter of opinion on that.
About going larger, well.........it IS kind of hard to tell what you are capable of grinding away and what your not from just reading posts and seeing pics on here, ya know? I didnt want to get into something to big, and was originally planned to be just a cleanup of the heads and whatever. This is only my first time, and not having money to fix anything else I may happen to screw up (ie, going into a water port, or whatever), I figured it's not worth the risk to try and go extensive on the first set....just take it easy, go slow, and learn from it, as I am SURE this will not be my last set I ever do.
F-Bird: Ya I wasn't real sure on what all I could grind off on the seat guides. I did take them down a little bit, again not very extensively, just to make sure. Next time I'll know to take more off right? I didn't see any need to go any bigger on the valve sizes, as this will still be a daily driver, not some phenomenal drag car. Maybe on the next engine I build perhaps. Like I said, being in college doesn't leave a whole lot of room for other stuff. I am barely able to do what I'm doing without going broke as a joke. I just didn't see larger valves as a top priority. Thanks for the advise!
Sitting Bull: Ya I probably should have got a cutter blade, but I was able to reach most of the spots I was concerned with with the stones I had available already, so I didn't worry too much about it. Next time I'll make sure I get one tho. And no, it WASN'T that hard! Like I said, just use common sense and have lots of patience and time available........Think it took me about 4 weekends straight (4 saturdays, 1 sunday) of about4 hours apeice, or less maybe.
I think I'll still be happy with them, maybe I coulda gone a little more, but like I said, I didn't want to screw anything up and be TOTALLY out of a car this summer!

Thanks guys,
-Ben

 

BTW, I realized I am missing some pics of being completely finished, of the bowls. I am going home this weekend to pick them up from the valve job, so I'll post them on the page when I get them up.

And I DID do a gasket match on the ports also.

 

305SBC: This is not a theory it is an observed fact.
Well researched.
This fuel washing happenes at part throttle and at full throttle.
Resulting in higher Brake specifics #'s less horsepower
less gas mileage and higher pollutants. All because raw liquid fuel is passing right through the motor.
But once the intake port and certain critical points in the chamber are "roughened up" again the fuel wash goes away
and brake specifics improve and emmisions go down.

Internal combustion engines are funny things. They don't want to run on opinions very well.
But you can take heart in the fact that more than one mechanic and engineer has got caught having to change their theory to match what it actually happening inside an engine.
I include myself in this. So you have lots of company, many with expensive degrees in engineering and physics.

 

Thanks I needed that!

by the way I have an extrude honed intake with a carburetor and i have never had any fuel wash.

 

:hail: mechanic and engineer