Intake port matching
Thread Starter
Racer
Joined: Sep 2004
Posts: 424
Likes: 2
Intake port matching
I am in the process of port matching my intake to my AFR heads. The size difference is substantial. The holes for the the intake bolts are larger then the bolts, so I fabed 2 studs to thread into the head with sleeves on them to match the intake bolt hole dia. I then put blue prussian on the head ports and bolted up one side. However I wonder how this will all line up when the gaskets are in place and both sides are bolted down. I am using AFR recomended Felpro gaskets which they tell you not to use for port matching. How do you guys do this??
Melting Slicks
Joined: Jun 2002
Posts: 2,844
Likes: 99
From: Orrtanna Pa.
I just did my Vic Jr intake and had the same concern.I found some nylon bushings at Lowes and they fit the intake bolts and the holes in the manifold. I tacked the intake gasket down with RTV and let it dry with just the bottom of the gasket stuck in place. Then I set the manifold on with the bushings and in "theory" the ports will line up.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
I really HATE! the fact that most new intakes are comming with "slots" instead of holes in them. The best method to Port match will be to scribe a line at each end of the cylinder head at the bolt centerline, take a "used" gasket like you are going to run and place it between the intake and the heads and bolt the assembly together, mark the intake at the same centerline, disassemble, take a thin sheet of paper or cardboard, use the sheet to cut out the openings with an Xacto knife to give you a "real" template of you port layout (if it is thin, you can run your finger or a tool around the port openings to give you a "witness mark" of the true port layout), mark you centerlines on your template and transfer the template to the cylinder head using your centerlines you located in the "mock-up" assembly. I know this sounds like a lot of work and it is but, it is worth while if you have a 7K RPM or higher motor. One last alternative, maybe a local machine shop has a set of Brezinski Racing port match templates and they will mark up everything for you for around $15-20, these templates save lots of time but, are not cheap to purchase (about $100 for one and they need at least 2-3 to cover the many gasket sizes of a SB Chevy.)
Le Mans Master
Joined: Oct 2000
Posts: 8,897
Likes: 1,356
From: Santa Ana CA
OK, here's my technique.
First port match the intake and heads using the desired gasket. Remember, you are porting them to the gasket specs and not to each other. Once done, stick the gasket to either the intake or heads using a spot of gasket sealant making sure it lines up perfectly.
When dry, lay the manifold in place on the heads. Take a piece of copper wire and "feel" along the inside of the ports at the manifold/heads interface. Slide the manifold around until you get this to feel as smooth and seamless as possible. This is the desired position.
Now take chalk/crayon/marker/whatever and mark the exterior of the manifold and heads with lines that will enable you to repeat this position. Remove the manifold and lay in the bead of silcone at the valley (as opposed to the front/rear gaskets) and let is set up. When you are ready to install the manifold, CAREFULLY drop it in place so your marks line up. (You don't want to be wiggling it around 'cause is messes up your bead.) This pretty much ensures the best match.
The key to power is in the attention to details.
First port match the intake and heads using the desired gasket. Remember, you are porting them to the gasket specs and not to each other. Once done, stick the gasket to either the intake or heads using a spot of gasket sealant making sure it lines up perfectly.
When dry, lay the manifold in place on the heads. Take a piece of copper wire and "feel" along the inside of the ports at the manifold/heads interface. Slide the manifold around until you get this to feel as smooth and seamless as possible. This is the desired position.
Now take chalk/crayon/marker/whatever and mark the exterior of the manifold and heads with lines that will enable you to repeat this position. Remove the manifold and lay in the bead of silcone at the valley (as opposed to the front/rear gaskets) and let is set up. When you are ready to install the manifold, CAREFULLY drop it in place so your marks line up. (You don't want to be wiggling it around 'cause is messes up your bead.) This pretty much ensures the best match.
The key to power is in the attention to details.
Burning Brakes
Joined: Feb 2005
Posts: 894
Likes: 91
The right and only way to gasket match
Have heads on engine with head gaskets in place, lay intake gaskets in position(on the heads) and hold in place with 4 small pieces of masking tape. Choose four corners on the intake manifold where you can drill 4 small 1/8" hole through the intake(go right through the gaskets also until the drill point rests on the head itself), one at each corner. After drilling, remove everything and use the same drill to line up the gaskets with the manifold on the bench. We use "cleco-buttons" to mount the gaskets. Mark the ports off with the gaskets still in position. To make it all a bit easier, mark the heads and the gaskets right and left ahead of time. We can actually get the intake port to sit inside the head port by
.020"/.030", it's all that accurate. And it's a "dead-on" fit. Thanks, Gary in N.Y.
A tip- If you're going to port heads, do that part first. We drill the manifold on a drill press ahead of time, just making sure we hit the gaskets when we back-drill them. It sounds really involved but it's real easy!
.020"/.030", it's all that accurate. And it's a "dead-on" fit. Thanks, Gary in N.Y.
A tip- If you're going to port heads, do that part first. We drill the manifold on a drill press ahead of time, just making sure we hit the gaskets when we back-drill them. It sounds really involved but it's real easy!
