So I was cruising the web looking for a safe way to remove the carbon build-up off the back of valves and stumbled across this write-up on basic DIY head porting.

http://www.sa-motorsports.com/diyport.aspx

There's nothing too radical in the procedures, just basic port matching, cleaning up the bowl, and blending/smoothing contours. This does not fundamentally change the shape of the ports. On the 5 liter SBC used for the write-up, these basic procedures provided the following flow bench results:

Average increase in intake flow - 6.3%, more at lower valve lifts
Average increase in exhaust flow - 7.5%

If these results transfer over to the 2.8, that could be good for 8-9 Hp for a few days with a grinder, not bad.

Still looking for a safe way to remove carbon build-up from valves, anyone have suggestions?

Cheers

I usually just pull them out and use a wire wheel on the carbon. Check for excessive play in the valve stem area because the guides might need to be redone (machine shop job). Use some duct tape (at the bare minimum) to protect the seats while you are doing bowl work. Don't mix up which valve comes out of which hole and lap them when you re-install. The work itself isn't difficult but it can be very time consuming.

David

I was worried that a wire wheel might be too aggressive, didn't want to scratch up the mating surface on the valve.

Cheers

The fiero V6 does not need to be opened up !! just cleaned up and 0f course leave the fins,,just a clean flow to the valve.. Port match is advantagious on the V6 ..It is the exhaust manifolds that strangle the V 6,, the sheet metal blockage needs to be removed,it is very obvious ..then the weld blockage which is like a gate at a dam..Opening up the exhaust manifold is the single best modification you can do to a V6..Do it right this single modification will yeld 5 to 8 hp this is more important than head porting..you only have to look in the manifold ports to see why..A custom professional port job on the ex manifolds will give 7 to 10 hp but this is beyond the tools and expertise of the average forum member because you have to work inside at the curve
Do not forget to open up the Y pipe and clean this up the 1 to 3 hp here are more important than the numbers because you recieve mid range acceleration and better MPG from the y pipe & the manifold..
Port match well worth it on the fiero I have recieve flack on this before as not worth it ..I have little fiero port experience but have many years on scooters harleys triumph and use to build race bikes,,My bikes were fast because of attention to detail.I had no secrete and attention to detail is where the performance is in the V 6

With porting of intake ports, port match ,ex manifold & Y pipe you can have a V6 with 130 hp that gets 25 mpg around town(4or5sp) this is a win win situation but a lot of work

Well, when I get to it, I'm not planning anything radical, just a gasket match blended into the runner, clean up the "short side" and generally smooth things out and fix casting flaws. No plans to remove the sharkfin, just clean it up. Might consider whether unshrouding the valves is worthwhile - need to take some measurements first.

Porting the exhaust manifolds and y-pipe as you have suggested is in the plan, as is gasket matching the intake manifold components (noticed a number of areas where the three intake pieces didn't fit that well.

I have no real pressure to get this project done, so lots of time to fiddle with porting. Puttering around in the garage is relaxing.

Cheers

The curtain is the most important part of the airflow.. The intake manifold and intake port depend on this available air.. this is the start the most important part of the power increase
I will not go into the port match detail post I did.. it is in the archives
Port match is IMPORTANT The people on this forum that slam others for wanting this are not knowlegeable,,The performance magazines now only list performance products that benefits there sponsors (good policy) and many have not been told of the benefits of port match
If you want top power your ports better be aligned perfectly PERIOD
On a street engine not so important but the better the job the more power .it is difficult to have perfect port match
just smooth the entry and straighten the walls open up the top
If you have the time ,to match gaskets to port, you only have to go in an inch smoothing to a smaller diameter as you move in
Do the same to the intake manifold of course you want no wall block!! the intake manifold is smaller than the intake port!!
the exhaust port is smaller than the exhaust manifold inlet!!
Read the many post on intake manifold porting
I would only cut the valves if you have a very steady hand make them all the same
Porting is far superior to a cam install because it improves with out loss,and increase MPG ..porting !! win win win win
This post and my detail port match post is based on my own experience and information plagerized from artcles by the real pros like Modello & Helgesen,I know little

[This message has been edited by uhlanstan (edited 05-14-2008).]

When I took a turn doing porting for the first time I posted the pics. The outcome of that porting job is that the engine develops its power between 4,000 and 6,000 rpm. I have found it is not the right power band for the street, but a great road racing power curve.

My next set of heads will not be hogged out quite so much. I will probably try to match the throat of the intake runner volume to the valve airway volume, do a lot of smoothing on the curves, with re-cutting around the valve stem opening to ensure smooth air flow. Also cure the shrouding of the valve opening in the intake bowl. So, the intake will not be quite so free flowing, but still way more than stock.

On the exhaust, it does not hurt to have a stepped exhaust. In the first porting I matched the exhaust runner to the exhaust manifold (ported +Y pipe port). On the new build, my exhaust headers are 1.5" pipe so the exhaust will be stepped. The exhaust runners need to be like mirrors in smoothness if you can do it. The hump beside the spark plug weld needs to be ground down. It is interesting that if you measure the D shape in the exhaust runner and the D shape in the Y pipe, they aren't very different.

As for working around the valve seats "DANGER WILL ROBINSON". I have a friend doing boost and he smoothed the inside of the combustion chamber to remove the potential hot points for detonation. I did not do this because to smooth the combustion chamber lowers your compression.

Also, what I learned from my first port is that the Fiero cam will support high rpms. I added 1.6 rockers, but the cam did ok. The engine keeps pulling when I chicken out. It probably revs to 6,500 or even 7,000 rpm but I don't have the guts to do it.

On the next build I am putting in a cam with higher lift and I am advancing the cam timing 4* to bring my power band down. It is my intention to have the torque come on at 1,000 rpm. (after discussing the project with the Crane Techies). I'll be aiming to have the power drop off at 5500 rpm. Why so low? The gearing on the 3.65 Muncie seems to like the original rpm band of the engine. I am betting the power coming on lower than 4,000 rpm is what the power train wants. If it doesn't work, I'll simply put the cam timing back to "0" and if that doesn't work, I'll leave room for more porting if I need it.

Porting is a almost voodoo to the amateur and the pro's who have bench flow testing equipment still experiment on a frequent basis. Quite a science for a hobbyist.

Arn

------------------

quote Originally posted by TiredGXP: So I was cruising the web looking for a safe way to remove the carbon build-up off the back of valves..Still looking for a safe way to remove carbon build-up from valves, anyone have suggestions? Cheers

I use Marvel Mystery Oil in the gas because it removes the carbon on the back side of the valves and the piston tops, too. MMO also provides lubrication for the top end and helps keep the injectors clean. You can also get an instant cleaning by injecting water or Sea Foam into the vacuum line coming off the intake.

I would keep the basic ports the chevrolet engineers did a good job here ,it needs to be cleaned up as mention earlier I would do the port match but not open up the whole port,, arns is correct and his post is a wealth of info but keep the internal ports small,, do not open "wide".. The exhaust manifold & Y pipe is the most important link in this chain

Yeah, I've been spending a bit of time googling this and that since starting this project