[JBurnz400]

So Im building my first engine, and just got my heads back from the machine shop. Everyone I've talked to said I should do gasket matching before I install the heads. I have a basic understanding of what needs to be done, but I could really use some help if anyone knows of good technigue as far as what dremel head to use, how to line up the gasket properly, pretty much any advise, or link to web page, book, ect would be greaty apreciated and helpful.
thank you

[JBurnz400]

So Im building my first engine, and just got my heads back from the machine shop. Everyone I've talked to said I should do gasket matching before I install the heads. I have a basic understanding of what needs to be done, but I could really use some help if anyone knows of good technigue as far as what dremel head to use, how to line up the gasket properly, pretty much any advise, or link to web page, book, ect would be greaty apreciated and helpful.
thank you

[quicksilver97ta]

The gaskets should have a round plastic insert that fits in the bolt holes I beleive. In any case use the bolt holes for proper alignment. With the gasket in place, take a scribe or something else thats sharp and outline the inside of the intake passages making sure you leave a mark you can see. Do the heads and the intake. Open the passages up to the outlines and blend them back at least 1/2". A metal bit will remove material the fastest but will also be rough, switch to a stone bit once your close for a smoother finish. Always keep the tool moving across the material, dont just grind in one spot and good lighting is important. I'm sure others will chime in here soon. Good luck.

[critter]

Here's how I do it.

www.arkansaspontiacs.org\techstories\Gasketmatch.p df

[dwainm]

Either way will work fine. I usually do mine before they go to the machine shop though, for cleaning puposes. If you're going to do it now, I would completely dissasemble them, and make sure you get all the metal powder out before reassembly.

[Steve C.]

So now you've port-matched everything on your Pontiac motor.... make sure you don't install the intake incorrectly, all your port-matching can go out the window and the flow numbers can deteriorate. You might consider cutting off the water passage and install it on the heads seperatly. Butt it up against the timing cover so that it doesn't leak.
Or... like many you can "slap-it-on-and-go" and probably never know the difference. But all the little details will add up.
Nice story and photos Chris.

[critter]

Thanks, Steve.

He's right about the port matching. You'll notice I mentioned that in the heading of that story. That's going to be in our next newsletter. With out getting the ports aligned you're just spinning your wheels doing the gasket match.

[455firebird1969]

What about the heads? My experience is the heads need more work that the intake. I figure the heads need to be opened up to RAIV specs first.

[455firebird1969]

I guess I should have read the story first...

[455firebird1969]

What happens if you port the heads but you leave the intake alone? When you open up the intake to the same as the heads (RAIV , the air/fuel charge hits that pushrod buldge in the heads, what happens then?

[critter]

Smaller to bigger is OK but not optimum. Bigger to smaller is an absolute train wreck. Matched ports are best.

Think of air like you would water flowing down a stream bed. If it hits a smooth, narrow channel it pics up speed. If there are smooth river stones in the bed it will flow gently around them without much disturbance.

If it hits a narrow channel plugged up with broken bricks, the water gets very turbulent and backs up. There will be tons of eddies and swirls.

If a stream hits a wide smooth channel, it slows down and spreads out.

Your objective is to keep air moving smoothly at a high velocity with as little disturbance as possible. This gives you the most efficent cylinder charge. (Velocity discussions get us into volumetric efficiency which is a book in itself and I'm not smart enough to talk about it)

Not much you can do about pushrod bulges except round them off as smoothly as possible. In my case (#16 Super Duty heads) the push rod tubes can't be altered so you optimize what you can and live with the rest.

Have you ever seen the intake port of a RAV head? That tube in the center of the intake port is shaped like an air foil to keep the disturbance to a minimum.

[455firebird1969]

Critter,

I guess you answered my question. "Smaller to bigger is OK but not optimum". Thats what I was guessing anyway, my last engine I did the heads but not the intake. I think I will open up the intake next time I have it off.

[critter]

It might help. The real key is port alignment. That's what Steve was talking about. Here's a down and dirty on that.

1 - Center the gasket on the intake. Mark four places on the gasket and matching marks on the intake. You want these on the top front, top back, front middle and back middle. Pardon my ASCII art but like this-

_ - - _

This will give you marks to keep it level, front to back and top to bottom.

2 - Take that same gasket and center it on your heads and make the same marks on the heads to match the ones on your gasket.

3 - Now comes the fun part. Make all the marks line up. You might not be perfect but get them as close as possible. This will give you your port alignment.

Cutting off the water crossover is the only way to go. This lets it pull forward independent of the intake and get a proper seal with the water pump while NOT pulling the intake ports out of alignment. Does that make sense?

[JBurnz400]

thanks for all the replies, After working on them for awhile, I notice some of the ports, the Gasket sticks over the port. IN this case, should i remove material from the gasket as well to match the port?????

[critter]

Sure. That way you keep that smooth transition. I had to do that when I used a set of Butler's intake gaskets. I won't use them again. I think the Felpro's are a much better gasket for this application.