Port matching questions

[cOmpressor]

Well I'm ready to port/gasket match my intake manifold to the head and the head to the exhaust manifold. I just have a couple of questions about sizing and all. Are all gaskets the same size or is OEM smaller/larger? I bought a RockAuto rebuild gasket kit and the gaskets don't seem to be OEM, no way to tell that I know of, and are much larger than the runners. About 3/8 inch all the way around each runner on the intake and a little less for the exhaust. Is that the normal amount that needs to be removed to match?

I know this topic has been beat like a redheaded stepchild but I couldn't find anything pertaining to my exact questions. Thanks in advance and any other tips on porting are welcome.

 

[cOmpressor]

Nothing? I'm out in the garage doing it right now so hopefully someone has some input soon.

 

[bazeng]

I can tell you that oem gaskets are slightly larger than the stock ports.

 

[prove_it]

glad to hear someone is spending some time on port matching.
here ya go...
your aftermarket gaskets will be a bit different than oem. always will. not sure in which way but it doesnt matter. just as long as you size the ports to the gaskets your using.
Biggest thing is make sure you have a step.
going from the intake to the head you will want to make sure that the is a step so that the head has a bigger hole than the intake.
do the same on the exhaust only make the exhaust manifold bigger than the head.
this helps with keeping the reversion alive and well. without it you'll actually lose power and may cause some drivabilty issues.

 

[cOmpressor]

I've gotten a couple of PM's about this with varying answers. One I trust over everyone else says not to open the ports to the gasket size and not to "step" the runners either. I was told to match the intake to the head and the same for the exhaust and that's all. If anyone has data stating otherwise I am interested to hear and pictures are also welcome.

 

[Olson]

Scott
When you do the porting
On the intake side dont make it super smooth you want it a little rough so you get good atomization with the fuel and air.
On the exhaust side make it glass smooth.
When i ported mine up last year i used a good carbid bit and opened up the exhaust side alot on the sides and the spliter in the middle.
The intake side i just cleaned up the casting flaws and hit it with a sading barrel.
On the valve seats or right under them you can put yuor finger in there and you will feel a lip in there. use your sanding barrel and smooth that out and thats it unless you know what you are doing. You can make alot of power right there or you can lose alot of power right there. so i just cleaned that lip up.
Hope this helps
Take your time and messure your ports to the same size and eyeball them up as good as you can since you dont have a flow bench.
Jake

 

[cOmpressor]

Who says I don't have a flow bench /ubbthreads/images/graemlins/wink.gif all that info is good to know, most of it I've heard but thank you for the info. I'll post some pics when I'm done and your right about those stupid lips on the bowls.

 

[Kenny_Kline]

What I did was install +1mm oversized valves to take out most of that lip that you guys are speaking of then blended the rest of the bowl into what was cut on the seat.

On the intake side, I took out the casting flaws and then port matched the intake manifold to the head openings. I left the head intake openings alone as far as the size goes. I am aslo using a 2G head and 2G intake manifold...

On the exhaust side, I took down the divider and then opened up the entire exhaust side to almost a gasket match. The exhaust manifold, have it stepped just a little bigger than what I ported the exhaust ports on the head at.

Also in the chamber, I took down the inperfections near the valve seat and on the sides of the chambers to help the air flow smoothly out and around the valves.

I dont know if I am going to make more power but I sure as hell hope I do. I didnt do to much and if anyone would like to test my head (flowbench) and put up the results, that would be cool. All you will need a is a stock 2G head. I would even put up this head against a stock 1G or even a ported 1G