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porting question?

2K views 21 replies 9 participants last post by  nicefrog 
#1 ·
I have read alot of threads here and by the sound of it porting is a good thing. what exactly is porting, what parts can u port, is it tough, or how much would a pro charge? ballpark? thx finman.
 
#3 ·
<a href="http://www.sa-motorsports.com/diyport.htm" target="_blank">DIY porting</a>
check this article. i bought a grinder at canadian tire for $60cdn and buy dremel bits as i need them. it's probably more economical to buy a set of bits though. unless you're rolling in dough, don't pay somebody to do this. it's not hard to do and kinda fun - just take your time. practice on junk heads if you can, and be very careful around valve seats!!!
 
#4 ·
Cast iron head porting is an endless subject. The novice can increase flow on a stock set of heads simply by matching the intake and exhaust ports to the manifolds bieng used and deburring and polishing rough factory castings. This is done by transfering the dimentions from the manifold to the ports using a cheap set of gaskets or heavy construction paper. Relieving the valve bowls requires machine work. Once the combustion chambers have been polished, they have to be CC'd to get them all back to the same size. This can be done with a peice of plexiglass with 1/8 holes located over the chambers. You'll need an accurate means of delivery to measure exactly how much mineral oil you deliver to each chamber to determine it's exact size. Starting with the smallest chamber, carfully buzz off material, preferably from high spots in the castings, till all chambers look alike and all CC out the same.

I'd practice on an old set of junk heads first.

It's fun and rewarding - just DO IT! :D
 
#6 ·
I used to port two stokes when I was younger that was fun but there it's more about changing the timing in allready well made ports, it's heaps more rewarding in the rough casting quality you get in old Chev heads. I use a cheap air powered die grinder, get a long nose one aswell if you can, it's probably not very efficient using a compressor all day to power it but it gives you very good speed control. With that I use a carbide cutter which you can get from your local engineering supplies shop, they last just about forever. I also use cheap chinese grinding stones sometimes but really the carbide cutter cuts faster and smoother and doesn't wear out, then I polish the exhaust ports and combustion chambers with those flapper sanding wheels, as long as your carefull with the valves seats (cutting down the casting ridge right near the seat with a carbide cutter is like walking in a knifes edge, exhilarating stuff!: )) then the rest of the job is easy as you like. Everyone that owns a small block chev should own this book "How to Build & Modify Chevrolet Small-Block V-8 Cylinder Heads (Powerpro Series) by David Vizard" his other books are great too but this one, it's special
 
#7 ·
"All it takes to bowl port is a carbide burr, die grinder, and some patients."

Lots and lots of patients! Thankyou. If you can uniformly blend and port valve bowls like a good fly cutter can, your hired. a die grinder burrs and crocus paddles are only good for finish work, unless of course, you want to make a career out of destroying good vintage cast iron cylinder heads.

<img src="graemlins/nono.gif" border="0" alt="[nono]" />
 
#9 ·
steppenwolf - I was in a hurry when I posted, My mistake. I've flycut surfaces in a Bridgeport but I've never done valve bowls with them, sorry. What DO I use to rough cut bowls with? I use a Bowl Hog, on a valve guide madral with three 60-75 degree carbides. Definatly NOT a BURR in a die grinder!! <img src="graemlins/nono.gif" border="0" alt="[nono]" />
 
#13 ·
Just so ya'll don't go away mad, die grinders and burrs are great for match porting intake and exhaust ports and cc'ing combustion chambers. Using them for initial bowl relief is like using a screwdriver for a punch. There is a better way, and it's well worth the cash. I'd never sic a novice on a decent set of castings, equipped with nothing but a die grinder. I wouldn't do it and I wouldn't tell anyone else to either. There are all kinds of "Assembled" heads available that I wouldn't give you fifty bucks for, without seeing the bowls, for obvious reasons.

I've been ripped off before, can ya' tell?

:D ;) :D
 
#14 ·
Just so ya'll don't go away mad, die grinders and burrs are great for match porting intake and exhaust ports and cc'ing combustion chambers. Using them for initial bowl relief is like using a screwdriver for a punch. There is a better way, and it's well worth the cash. I'd never sic a novice on a decent set of castings, equipped with nothing but a die grinder. I wouldn't do it and I wouldn't tell anyone else to either. There are all kinds of "Assembled" heads available that I wouldn't give you fifty bucks for, without seeing the bowls, for obvious reasons.

I've been ripped off before, can ya' tell?

:D ;) :D
 
#15 ·
Once I read a guys web site where he ported his own heads and got a slightly worse flow on the after ported exhaust port at some lifts but you only had to look at the pictures to see that it was a bad port job, that's the only time I've heard about not gaining flow and he still gained heaps and heaps of flow on the intake with a grinding stone in the bowls, he just didn't grasp the exhaust concept.

I still say anyone with steady hands can make any shape they want down to +or- one millimeter _easily_ with a carbide cutter and a air powered die grinder, how can you get a good port bias going just cutting the bowl with a machine? *confused alot*. The standard bowls on my 305 were the most garbarge part of the whole engine, they were classic production line stuff, big ridges all over the place, they wern't going to do anything apart from smash air straight into the back of the valve, maybe it's a different story for high tech aluminium heads, but I really can't see how you could ever make an old iron head worse than they come from the factory especially if you read a book about it first
 
#16 ·
Primemover,
I am no professional machinist, but then again neither are you according to your profile. I do know that both of the machist I have used in the past do not use this meathod you are talking about. I guess they are just neanderthals getting lucky that they are building all those 1000 plus HP N/A engines. I know the head guy at my local shop, and he does everything by hand.

Also, if you were a machinist why would you ever suggest using a fly cutter because you are in a hurry? That is like a painter accidentally saying that he used a Wagnor Latex gun for the urethane clear coat.

A burr and paper rolls will defenately work for a bowl port job, and it is what most shops use.

Chris

[ January 15, 2003: Message edited by: TurboS10 ]</p>
 
#17 ·
I use a french scraper.

Using a tool to cut bowls out is great if your building 100's of engines of course, all the tool does is make it easier to remove lots of material in relative safety since you don't have to worry about hitting the seats. A die grinder has to eventually get in there to remove the inevitable ridge left from the cutter so what does that prove?

Either I don't get it or someone else doesn't, using a carbide cutter to grind cylinder heads is still the way all blending is done. Most of the big name Nascar guys are using CNC pocketed bowls and port match just so it is repeatable and identical from port to port, not that a person couldn't achieve the same results by hand. All these labour saving tools are just that, they are there so the guy behind the machine doesn't have to think.

Porting heads is not easy or quick, these tools drastically shorten the time to get to a hogged out port/bowl...but that doesn't automatically make it better...just faster...and more idiotproof.
 
#18 ·
Just to add to all the fun.... The current trend in Winston Cup as far as port development is concerned is that along with in-house development, outside vendors ( namely cylinder head specialists) are contracted from all over the country to develop new port shapes. The vendor will receive a cylinder head section (raw casting) and Valves. They then grind, machine, weld, Marine Tex, use a paint scraper, whatever to develop the best shape possible to produce the best flow/power numbers. Sometimes it's not how much flow, but what the shape is that generates good power numbers. From there if the port shows some promise the shape is then digitized and converted to a CNC program. A full cylinder head is then CNC machined and put together for dyno testing. The vendor is obviously paid for the submission. This is one way teams are tapping into the vast resources available across the country.
 
#19 ·
If you'll notice, I said Bowl Hogs are needed for "initial" bowl relief. What is done to them after that, is up to the "flowmaster" doing the job. Hogs get bowls all uniform to begin with, and a lot faster and more acurately than even a so called 'expert' can with a die grinder. Frankly, I enjoy spending hours on the CC bench, rather then chasing my tail around in a valve bowl with a burr... Ultimately you'll all do what works best for you, irregardless... That's the beauty of being a backyard flow genius. If it works for you, it's gotta be just the ticket for everybody. :D
 
#20 ·
You guys probably don't about know Larry perkins but he's a race car engineer/Team owner/boss/head driver and ex Formula one driver, about 10 years ago I saw him on TV in his workshop getting stuck into set of heads for his new touring car with a carbide bur in his die grinder, he then drove that car to win the biggest race in Australia, a lot of the other teams had engines built by nascar guys in the states, he just retired a couple to months ago to dedicate all his time to his real passion of restoring vintage tractors and building up a museum for them, that's the kind of thing I like to see, who knows how many more Larry Perkins are out there but get scared to try doing there own stuff? who says the guy in the engine shop can port better than the guy in the fish shop just because they happened to end up where they did, I believe there are people out there with Ayrton Sennas driving skills that have never even driven a car!: )

<a href="http://www.castrol.com.au/motorsport/print_larry_perkins.html" target="_blank">http://www.castrol.com.au/motorsport/print_larry_perkins.html</a>
 
#21 ·
Frog - look at the valve bowls on a stock set of 186's and tell me you want to wast time on them with a die grinder... I can spank those babys out with a bowl hog rough cut, and finish contour them for flow, with a carbide paddle, and be entertaining the little woman while you are still out in the garage having a tizzy, wondering if you're ready to stike water or not...

Dang! I really don't care what anybody does with a set of cast iron castings, as longs as they pull out the valves before they try to peddle thier mistakes at the swap meet. ;)
 
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