Ron the pool man, cuisinartvette has clued me in on where to get some head porting stuff, some pointers on how to do it. thanks again

Going to buy a set of iron eagle dart heads 49 cc chamber. Now I have no experience porting heads so im not touching the intake side unless it just has say a casting ridge to get rid of. Would want someone that truly knows what they were doing to do the intake side or simply invest in what may be a better head if it came down to that. But I think im going to work on the exhaust side to improve it. My plan is to increase the bowl, do some on the long top side and its width leave the short side floor alone. Its simply pushing air out can't see how some more volume would hurt as long as im keeping in mind air does not like to do curves.

Im doing higher rpm even if its a small engine so I need it to be at its best in that area. Now the 200/215/230 and 227 cnc head all show to have the same valve placement. 200 =2.02, 215 = 2.05, 230/227 cnc = 2.08 intake valves. What if I were to do ( if it can be done like think without calling ) Use a 200 runner because its at rpm and below 4000 rpm does not matter. What if I were to put a hollow stem ferrera intake valve of 2.08 in it. Now no doubt a 331 with a 2.02 valve is in nice shape. If you want to get sick do the math on a 427/ 454 on up big blocks lol. Going to do the exhaust thing. The intake valve size may be in crazy land, but remember it is high rpm only deal, What do you think.

 

25+ years ago Dart came out with the Sportsman II 200cc heads. The chambers were not madern heart shaped, but the rage on porting was to install seats that would allow 2.055 intakes for max ported flow.

210-215 heads came with 2.08 intakes because the valve guides are wider apart.

the modern 227 might have alter valve guide placement called 60/40 instead of the common inline valve placement and can be made with 2.10 -2.125 intakes. these require offset lifters/ and or offset rockers as do some of the 210-215-220 heads.

Most shaft rocker systems use offset rockers for valve train geometery

 

None of them have the 60/40 valve placement can use a standard stud girdle. when they go to a 2.10 on up that's when it looks like I see the 60/40.. would have to call dart to see if its even doable for the 2.08 and it may be silly to even do it on such a small engine.

The old trans am cars well there in a rolling momentum not trying to get anything going from a dead stop. Its a completely different type head canted valve oval or round ports. But the 302 ford had a 2.19 intake valve it made a little more power then the chevy without the use of a cross ram.

Back before they came out with the iron eagle upgraded some from the old head. There was an article done on the eagle where they used everyone of there heads on a 355 low rpm street engine like most people build the standard stuff hydraulic cam edelbrock high rise dual plane. They tested the 165,180,200,215,230 head on this engine. Before the test they felt like the 180 head would give the most overall power. Not just the most hp but they were looking at what counts the overall power all through the rpm range of the 6000 rpm engine. To there surprise the 215 posted the most overall power, the 230 came in second to it then it was 200 180 165 on power. The 230 head got just a bit to big but not the burden on the engine the 200 on down heads caused so it still managed second even at being to big.

Does this mean on any companies head use a bigger runner most likely not..

normally I take what's written on parts in the Magazines with a grain of salt for this reasoning. Big companies, will just use these two as an example, you see edelbrock and comp cams flooding the magazines with advertising. These mucho dollars are coming in to that magazine for support that they need. One reason I would more tend to believe this article was that one companies heads were being used in the test. If it were a test between different manufacture's heads, then I would wonder has advertising money and the magazines needs messed with there results reported. I know me personally I almost never trust anyone when it comes to money.

One thing im wondering about these heads are angle cut to get the smaller chamber the valve angle ends up at 21 degrees. If im not pushing close to any limits on lift, I decide to stay with a flat tappit cam, will the standard 23 piston work.

 

Just think about what less valve angle does? One is more piston to valve clearance. But you open a can of worms because you also have to angle mill the intake and you can't hardly get the heads on and off on a studded motor. I would never do an agle milled head again.

My dart 215 heads were factory race ported with 2.08/ 1.625 valves because i intended to run a two stagged 375 hp N2O

 

 

Porting Cylinder Heads is a lost art, lost to the CNC machining center. Sure You can still match the Ports to the Intake and Exhaust, and un shroud the valves, but beyond that your better off changing heads. If Your still set on porting the Heads, buy a Flow Bench, get a lot of heads to exsperimate with, devote years of time to research, and You might start to rival the CNC Heads that are made today.

 

I would highly recommend going to the junk yard and getting a junk head to play with and gett some experience. I can't count how many times I've seen people ruin heads with home porting.

 

have not bought the porting stuff yet. I threw out some old heads does sound like a good practice plan.

 

I just did an intake manifold and will do my heads in a few weeks. This video was ok it does show what you can do with old school know how and a tad of elbow grease !

 

You might want to buy this book and see what he has to say about porting.


I used it as my guide to porting and did not mess anything up my first time porting.
Like you I didn't make any big changes on the intake side just smoothed out/ blended transitions and turns.
On the exhaust side I did open up the long side turn as it was somewhat pinched and looked to be restricting flow as well as smoothing and blending.
I left it all with an 80 grit finish.
Mine were aluminum and it still seemed like tons of work and effort. I don't envy you on iron heads.
I did practice on some iron heads first just to get an idea how to control the die grinder, worth doing so you don't ding a valve sealing surface or something.
On the valve surfaces I put duct tape on the inserts so that if I did lightly touch the valve seat I wouldn't gouge it and that worked pretty well.
I found it easy to forget how close the seats were to the tool when you get tired after flipping the head around for the 30th time.
Here was the results of my effort.

http://forums.corvetteforum.com/c3-t...ing-heads.html

 

elbow grease ! yes !!

 

I always say there are a thousand people out there who claim to port heads, but only a handful that know what they are doing.

The biggest mistakes I see are people grinding away the floor on the short side radius and hogging out the seat throat too big. The most important area is the seat area and just before and after it. There is a lot to be gained in seat shapes and matching the valve shape valve seat width, back angle etc... to that seat shape. Throat diameter to valve head diameter ratio is very important for low and mid lift flows. Having the floor raise before the short side radius and then having a gentle radius on the short side radius that continues around around into the chamber is very important. Air doesn't like to turn, you have to trick it a little.

Most of the CNC porting is done from digitizing ports someone had to do by hand first. That is how I did it with all the heads I have designed except for the last set of Top Fuel heads I did. We did it all in the computer. Took us a long time to get them where I wanted, cad computer programs don't always like the complex curves meeting together. George (gkull) has seen these heads and the street heads I did.

I've ported heads for forty years and it really takes a toll on your body. All hunched over looking in the port as you work. Carpel tunnel both wrists, compressed and bulging discs in my neck with a fusion at C6-C7. I don't do it much anymore.

Little Mouse, where do you live?

 

I have a whole lot of respect for anyone who could do that for forty years. That is killer work and exhausting. Not to mention the noise and metal dust and chips flying around.
Think I'd rather buck hay bales for a living.

 

I am abnormal . I found it fun doing the intake manifold..

 

It was fun for a long time. It's a constant learning process, and I love learning. It's also rewarding when you see the results, especially if your work contributes to someone winning races and setting world records!

The worst porting job I ever took on was for a friend, of course. He has a 28 foot Donzi boat with twin small blocks in it. He wanted to stay with the Vortec heads but wanted 2.02 valves in them and was building a pair of 383's that he wanted to hit 500 horse with. With 4 heads to do it was a lot of grinding and iron splinters in my fingers. I had custom valves made with special shapes and put 2.02 intakes with 1.580" exhaust in. You can't put a lot of duration in a boat motor and have it very friendly to use, especially pulling into the boat lift. The idle rpm needs to be fairly low and pull hard right from idle with big props that would let it run 90 mph. I got the intakes to flow really well at low, mid and high lift flow. To keep the overlap on down I used my proprietary radius seat cutter and a 35 degree back angle on the custom exhaust valve to get really high exhaust to intake flow ratio, especially in the low and mid lift. It was flowing 100% of the intake through the exhaust up to about .350" lift and 90% from there on. This allowed me to design a custom cam with more duration on the intake and much less duration and lift on the exhaust keeping the overlap down. The cam was a hydraulic roller so I could also have a fairly high lift on the intake with moderate duration. To make a long story short, we hit 500 horse with a big broad power-band and fairly smooth idle at 750 RPM and it pulls hard right from idle.

I swore I would never touch another set of iron heads after these though!

Just a side note. A 28 foot boat is scary at 90 MPH. The ex president of the company I work for has a 50 foot MTI and it is not scary at 150+ MPH.

 

40 hours spent grinding around in an iron head will save someone a lot of pain. Better yet, spend the $ to have the scrap set pressure tested when you're done

I don't think there's a lot of benefit for a home porter any more other than cleaning up the throat, bowl and the short radius a bit...but decent heads are already in good shape there. Just one guy's take.

 

There are people who port heads and then there are people who tune heads. Luckly I have a head tuner that works for me.

 

Just read your post again. Taking material out of the bowl on the exhaust side can destroy the flow. The exhaust on most ports will flow better if you fill in behind the guide and make more of a constant radius on the roof out towards the exit. The short side radius can be helped if it is not smooth or has ridges. It should be a nice smooth radius from the seat out to the exit. That goes for the intake side too.

I've seen more exhaust ports ruined than I could ever count! They are touchier than the intake side.

Just smooth out casting ridges and leave it at that. It is far easier to ruin a head than to make it better!

 

well ill just leave it alone save my money and time.

I don't know how long ago they started doing flat top rules in some classes of roundy round racing. but to increase compression they started angle cutting heads. Dart came out with heads that already done for them.

$500.00 I spent on the 450 Honda was not in my plans. But it has 6000 miles on it zero rust pitting close to as new one on the showroom floor in 1972 I know the owner dating back to when he bought it used in 1975. I could sell it for twice that. But something tells me the modifier in me won't let that happen. Plus when I had the 160 I rode a 450 seemed like a monster. Any 250 would destroy it today but it was a have to have thing.

 

That's a good buy on the 450. Leave it stock. Some of the old 60's and early 70's Japaneses bikes are starting to have some collector value. Most of them got abused, used up and thrown out or left to rot away outside.