Cleveland head porting
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Fleet Mechanic
Joined: Jul 2000
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From: SE Iowa
Cleveland head porting
I'm looking for a site that deals with specifically porting cleveland style heads. I've seen most of the ones that are generic, dont list those. I have a set of '72 2bbl C's that are begging to be opened up. Besides the exhaust bump and port matching, any other suggestions?
Stryder
Stryder
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Joined: Aug 2000
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From: (near) Denver USA
Cleveland head porting
There is a difference between port matching and "gasket matching."
Port matching entails modifying both the heads and the intake manifold to match the ports on those parts. It is a complex (and expensive) procedure. When done correctly, it matches the flow rate of all the cylinders, so the actual port work is different for each cylinder.
I would not recommend you attempt it unless you are already very skilled with grinding tools and experienced with a flow bench.
Port matching entails modifying both the heads and the intake manifold to match the ports on those parts. It is a complex (and expensive) procedure. When done correctly, it matches the flow rate of all the cylinders, so the actual port work is different for each cylinder.
I would not recommend you attempt it unless you are already very skilled with grinding tools and experienced with a flow bench.
Freshman User
Joined: Feb 2003
Posts: 28
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From: El Monte, CA
Cleveland head porting
Torque1st,
Where can I find thread on polishing the ports in the 400 heads, I'm especially curious about this bump in the exhaust. Do you remove it completely?
Thanks in advance,
Jerry
p.s. making any headway on the front end swap?
Where can I find thread on polishing the ports in the 400 heads, I'm especially curious about this bump in the exhaust. Do you remove it completely?
Thanks in advance,
Jerry
p.s. making any headway on the front end swap?
Senior User
Joined: Jan 2003
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From: Saraland AL
Cleveland head porting
I put '72 Cleveland heads on my 400. Got a really strong air powered pencil grinder (long, tapered grinder) and some carbide and stone bits. Be careful with the carbide, it removes material quickly.
I then ground down the hump completely. Then went to lightly open up the area around the exhaust pocket. After that, smoothed over with stones and smoothed out any casting flaws. Don't open up the ports, they're good enough.
Then I done some light work on the combustion faces. Make sure you are very careful around the valve seats.
I had stelite (hardened) valve seats installed so I could run stainless valves and cheap unleaded gas.
I then ground down the hump completely. Then went to lightly open up the area around the exhaust pocket. After that, smoothed over with stones and smoothed out any casting flaws. Don't open up the ports, they're good enough.
Then I done some light work on the combustion faces. Make sure you are very careful around the valve seats.
I had stelite (hardened) valve seats installed so I could run stainless valves and cheap unleaded gas.
Posting Guru
Joined: Dec 2002
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From: chicago burbs
Cleveland head porting
here are some pics of some porting work. http://raceabilene.com/kelly/hotrod/newmotor2.html
don't be afraid to explore the rest of the site. lots of territory everybody here keeps asking about.
don't be afraid to explore the rest of the site. lots of territory everybody here keeps asking about.
Posting Legend
Joined: Sep 2001
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Cleveland head porting
The exhaust port cutaway shows the most restrictive cross section in the passage. If you sliced a little farther below that surface or above it the port opens up more. The passage wraps around the valve guide bump. That cross section makes it look worse than it is.
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Posting Guru
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From: chicago burbs
Cleveland head porting
i didn't mean to bring it up again, but what good does the more open part do if it is right behind the not so opened part? me thinks it will cause the velocity in the port to crash, tumble, and roll as the gasses come into the larger cross sectional area. generally not so good for smooth, efficient exhaust flow out of the head. but like i was saying, my intention was only to offer the porting pics at this time. the 72 C heads are not of the restricted design.
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Posting Legend
Joined: Sep 2001
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Cleveland head porting
It is not "behind" the restricted part it is actually beside it as the gas flows. It is like looking down your own throat... You have that hanging down part that gets close to your tonge in back but there are big openings on either side. picture that hanging down part as the valve guide... The port is like that -Get the picture???
Some people can see things in their heads in three dimensions but others just can't, you may be one of the latter.
Some people can see things in their heads in three dimensions but others just can't, you may be one of the latter.
Elder User
Joined: Jun 2003
Posts: 886
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From: Houston/Hope BC
Cleveland head porting
I'm kinda guessing but I doubt there is anyone who does ONLY Cleveland heads. I really like the guys that worked on mine hear in Houston TX. They just did the finishing work, however. I spent about 20 or more hours on the heads at home first. About 3:1time on the intake side. The exaust is pressure flow so once the big improvements are made there is diminishing returns for time spent. The "fluid power designers handbook" says one 90 degree turn is like 10' of straight pipe in a vacuum system, so spend the time there.
The work calls for a steady hand and a good eye. I highly reccomend you find someone who will teach you, or get a set of practice junker heads to learn on.
I helps a lot you are a sculptor!
If you are just dying to mail those heads somehere, I guess I can email you a number, but I am counting on you finding a guy where you are. Ask around and find out who is doing dirt track cars or someother semi-serious racing valve jobs/heads in you area.
Highly suggest going SS valves!
The work calls for a steady hand and a good eye. I highly reccomend you find someone who will teach you, or get a set of practice junker heads to learn on.
I helps a lot you are a sculptor!
If you are just dying to mail those heads somehere, I guess I can email you a number, but I am counting on you finding a guy where you are. Ask around and find out who is doing dirt track cars or someother semi-serious racing valve jobs/heads in you area.
Highly suggest going SS valves!
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Fleet Mechanic
Joined: Jul 2000
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From: SE Iowa
Cleveland head porting
Well, I just pretty much SCREWED the pooch. Here I am smoothing away on the last intake port, when the stone catches a rouch part of the casting and POOOF. It skips and there goes half my valve seat! Take about pi$$ed!!!
Do I even have a prayer or will I be okay going to 4V valve size?? What about putting in hardened seats?? I guess if there junk, I could try cast rod and regrind. Any suggestions???
Side note. Thought of a way to do actuall port matching (not gasket match) Bolt freshly planed head and intake together, no gasket. Of couse they are both of the block. Pour the machinist dye down the intake and roll the assembly around. This should mark the difference between the two and tell you what to gring away. It sounds good anyway. I've got a couple of junk 302 heads/intake laying around. If I get time, I will give it try and let you know.
Stryder
Do I even have a prayer or will I be okay going to 4V valve size?? What about putting in hardened seats?? I guess if there junk, I could try cast rod and regrind. Any suggestions???Side note. Thought of a way to do actuall port matching (not gasket match) Bolt freshly planed head and intake together, no gasket. Of couse they are both of the block. Pour the machinist dye down the intake and roll the assembly around. This should mark the difference between the two and tell you what to gring away. It sounds good anyway. I've got a couple of junk 302 heads/intake laying around. If I get time, I will give it try and let you know.
Stryder
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Cleveland head porting
The dye is thin and will run all over.
The problem is the parts will never quite bolt up the same each time which will result in disruptive "shelves" on one or two sides of the port. In order to avoid this the intake manifold port is always made a little smaller than the head port. The manufacturers figure in core shift in the heads and the head manufacturing tolerances as well as the core shift and man tolerances in the manifold. Then of course you have your own assy tolerances.
You can carve a little out of these tolerances with a little careful matching. Unfortunately if you have to change out one component or rebuild the engine again your port matching is gone and you have to start completely over. You can save some work with careful component selection. People use the gasket as a reference point but gaskets vary between manufacturers, lots, and also from gasket to gasket (I used to design the machines they are made on).
-Get a new valve seat installed
The problem is the parts will never quite bolt up the same each time which will result in disruptive "shelves" on one or two sides of the port. In order to avoid this the intake manifold port is always made a little smaller than the head port. The manufacturers figure in core shift in the heads and the head manufacturing tolerances as well as the core shift and man tolerances in the manifold. Then of course you have your own assy tolerances.
You can carve a little out of these tolerances with a little careful matching. Unfortunately if you have to change out one component or rebuild the engine again your port matching is gone and you have to start completely over. You can save some work with careful component selection. People use the gasket as a reference point but gaskets vary between manufacturers, lots, and also from gasket to gasket (I used to design the machines they are made on).
-Get a new valve seat installed
Posting Legend
Joined: Sep 2001
Posts: 30,255
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Cleveland head porting
IMO- The only problem with the 4V valves is during low lift when the intake is partially shrouded by the cyl wall. This does not make a lot of difference in a big cam high rpm engine but in a lower revving street/daily driver engine it can make a difference.
Compromises, compromises, -always compromises in Engineering...
Compromises, compromises, -always compromises in Engineering...
Senior User
Joined: Jan 2003
Posts: 217
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From: Saraland AL
Cleveland head porting
Don't worry about the valve seats. I dinged mine up a lot. I intended on replacing them anyway.
I know it may not look like it, but the valve seats are removeable. Your machine shop can pull out the old ones and replace them. See my post above. You'll be better off getting hardened seats for modern fuel.
Torque1st; That's interesting. I used to work in a gasket shop. Getting good gaskets was easy then.
I know it may not look like it, but the valve seats are removeable. Your machine shop can pull out the old ones and replace them. See my post above. You'll be better off getting hardened seats for modern fuel.
Torque1st; That's interesting. I used to work in a gasket shop. Getting good gaskets was easy then.
Last edited by Coondawg; Jul 16, 2003 at 07:05 PM.