camaro87-alex

Hi there..

Today I started on my first porting job ever. I am very familiar with using a grinder since my job often has grinding missions, not on cylinder heads though.

I have a project going on, on my 305TPI engine. I have rebuilt the whole engine with new pistons and bearings and all other rebuild parts.

I also have installed a performance setup that includes: Higher lift cam, headers 3" cat-back system and a performance chip on my TPI.


So now it is time for my question. I have removed a lot of the guide boss at the exhaust ports. Will this affect anything?..I mean, have I removed too much of the ports?...I was thinking of doing almost the same on the intake side, but mayby that is not necessary?..

I am familiar with the grits and what kind of surface the ports should have so that one is okay. I am just wondering where to remove materials to improve flow.



Here are some pictures:

Sonix

iTrader: (1)

I've honestly never seen anyone remove that much of the guide boss before, which leads me to believe it's a bad thing. CNC ported race heads have more boss, which makes me think it's important.
Without much boss length you're bound to have more side play in the valve. I imagine it'd effect the ability of the valve to shed it's heat to the cylinder head..?

I'll wait for someone with more intimate knowledge of the subject to chime in here, I just had to sign onto this thread for information sake.

camaro87-alex

Yeah I agree with you, BUT there are still a lot of valve guide left. The lenght of the valve guide was about 46mm and now it is about 42-41mm so I don't think that would make problems when it comes to the side clearence on the valves, but of course I am no expert at all..

nascarfan7

You've removed too much material.

With that much support removed you'll see cooling issues with the valves, oiling problems and not to mention alignment problems as the valve seats.

You just want to clean up the rough areas and sharp edges. Short side radias/valve throat and the combustion chamber is where 90% the gains will be made on a street engine. Hogging out the port like that will slow velocity tremendously. Tons and tons of reading available on the web that can guide you.

One example...

http://www.pirate4x4.com/tech/billav...0Abrasives.pdf

Joe Mondello, an Oldsmobile engine specalist (go figure lol) wrote an excellent guide for home porting but for the life of me I can't find it.
I commend your efforts though. I'd try it with some salvage yard heads to get a feel then dig into your personal vehicle.

Good luck

camaro87-alex

damn...I was afraid of that..Think I have to buy me a set of new ones then, because sending cylinder heads to machine work in Norway is quite expensive....

305sbc

iTrader: (3)

In a lower power/stockish application with relatively low valve lift you will be fine. Around .450" or more lift and you will see accelerated guide & seat wear.

If you are really concerned or plan on high valve lift then you can get the guides drilled & reamed and get full-sized guides installed, iron or bronze.
Bronze does a better job of cooling the valve, and you can get them in "bullet-nosed" form.

I have actually seen this done many times, though much more often with stock Ford 302 heads. I've never seen a real problem come up as long as the stock cam was used. It's really not as big of an issue as you might think. It's more on the order of what happens when running incorrect rocker geometry, which is much more common. If there's a real worry about exhaust valve overheating, then that means there are other factors to address as well. Worn guides (also common) will also cause an exhaust valve to run a little hotter.

camaro87-alex

Wellwell. Finally somebody that made my day a lot happier and thanks for that my friend.

I see that I haven't wrote any information about my performance build up so mayby I would do that first.

I have rebuilt my engine so far with changing all bearings and pistons and measured every bearing clearences and everything was ok. My engine has about 86,000miles on it and is a stock engine.

Now I have installed a performance cam from COMP cams. It is the serial number 08-412-8. The intake lift is about .487 and the exhaust is .495.

The camshaft is recommended for my build up. Have been talking to a lot of guys that have done the same combo.

I have also installed Hooker 2055HKR headers so the exhaust flow will be much nicer now. And I have also installed a catco 9118 High flow catalytic converter with a 3" cat-back system from there.

I converted to TPI last winter also so I have the opportunity to make my own chips on the ECM. Have done a little bit of chip burning.

I know the valve guides will get a little accelerated wear time but will it be so much that in one year do I need to change heads or rebuild them in a year again?...I am not using the car for any racing at all. Just a daily driver that I want a little more performance on.

So you think I would be okay with that head?..I have not done anything on the intake side yet. I was thinking of shaping the valve boss guide more only...