I was about to re install the J2 intake manifold on my Rocket motor when I decided to check the ports against the gasket. The gasket was pretty close to the port shape of the heads. The intake manifold was another story. I didn't think to take any pictures so nothing to show. I cleaned off the intake ports and brushed on some machinists blueing. When it dried I bolted the intake gaskets to the intake. Then took a scriber and scribed the port shape of the gasket to the intake. Out came the air grinder with a carbide burr in it. I opened up the ports in the intake manifold to the scribe lines, which match the gasket. I really don't know if this helps much, but I have always done this whenever I removed the intake manifold. What is your experience with this. Does it help any?
Only port match if the head is smaller than the manifold. If it is the other war round than the intake creates "anti-reversion" dam [which can be desirable at low velocity] Do not gasket match the intake and head ports ,it is ok if the gasket is slightly larger. When idiots do this ^^^ they stall the air velocity by creating the reverse effect of a venturi [think of 2 trumpets facing each other] I have seen the results of simple DIY gasket port matching on a flow bench and the CFM went down slightly. If you do get the urge to hogg out the ports , trace the intake face onto paper and superimpose this to the head face. Don't use the gasket as a template
I've done it to just about every motor I've built. From mild street and up. Seen dyno tests and on a dyno with a hot street motor it was worth almost 20 horse. Cheap horsepower.... ....
So you've built an engine and dyno'd it. Then pulled the heads and intake off , dis***embled and port matched them. then re***embled and dyno'd the engine again Almost 20 hp gain from just port matching and nothing else. I've seen bigger gains because the savvy dyno operator re-installed the distributor in a different position
Years ago I funnel ported some old bb chevy oval port heads to match a rectangle port TR2X Edelbrock tunnel ram Worked pretty good .
There's a bunch of guys that have run rectangle port intakes on oval port heads for various reasons, and the results are surprisingly good. Not saying it's ideal, but the airflow through a port can be counterintuitive. Unless one does a real world test, there's no way of knowing, but in your case, (Olds), it probably can't hurt.
The ports on both my Cad. engines were miss-matched almost 3/8", intakes ports were high on one side and low on the other. Didn't hog them out, just made them match. I've port matched every "performance" engine that I had the heads off of for 60 years now.
I've used the grinder on some sbf heads in an attempt to use '77 air pump heads and went through a port, ruining the head. Not that ruining the heads was a bad thing in reality. Just made me buy a pair of aluminum Edelbrock heads, which are working out quite well with roller rockers. The gaskets matched perfectly to the heads and extremely close with the intake manifold. I'm not going racing, just want to enjoy my hotrod sooner than later.
In my nearly 60 years of building engines, port matching I rarely do and depends on the characteristics of the engine. To me, it is all about intake velocity and fuel suspension. In some cases, I agree with @Kerrynzl in which port matching can be detrimental. I have had numerous discussions with the Martins about Nail Head engines along this line. 250/292 Chevy engines lump port pieces are a good example of enhancing velocity. Shorter stroke/ high rpm motors may benefit along this line, especially for racing.
depends on application , stock or mild motors, usually like intake a little smaller than head. Some aftermarket intakes are so horrible that they need cleaned up regardless , like this Olds victor
Not on a street motor. I don't drag race. I would inspect the gasket match on the dirt track motors, but unless the mismatch was radical, I didn't do it.
Yes. I try to leave a Venturi effect if I can. At low to mid rpm where we all drive it defiantly helps..
I think it can help most any motor breath better, so I do it. Many aftermarket manifolds are made with smaller runners near the flange with the intent to port match, so I like to check to see what's going on. I've always used the method Smokey describes in his book of secrets, and feel better knowing what I have.
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