I stumbled on these two videos showing porting a Nailhead head. Any thoughts, does everything make sense? I think he took a pretty straightforward approach, and hopefully it gave him some good results. Maybe the guy who did the videos are on the board? https://www.youtube.com/watch?v=r7ytIuDbmkE https://www.youtube.com/watch?v=FaDdyfRzWI4
Some very good pointers on porting. It's kinda hard listening to Him with his accent. But you can get the gist of what he's talking about. I'm getting ready to do a set of heads and I'll go back and look at some of his details. :gp: Jim
Yeah, it's a bit tough with the accent, but I like his sketches and that he explains why he does everything so it makes sense. It would be cool to hear what someone that is experienced with porting nailheads would say about his work, since it seems easy to actually get worse results if you're not careful.
THIS!! I didn't watch the videos cause I am at the office, however if he is doing anything more than just a straight polish job or cleaning up the casting, he can very well kill the flow......easily. Nailheads are very finicky as we all already know and it very easy to kill a head. It is very unwise to do any actual porting to a head without the use of a flow bench.
On the Intake side it looks like he is just straightening out the flow. Just like his sketches show. The exhaust side looks like he's just getting extra metal out of the way. You're right tho, a flow bench seems like a Great Idea if you want them to work. Jim
It's actually me doing all those videos. Sorry for the accent and my really weird explanations, the problem was that it was recorded at night and I was really tired. It was pretty much impossible to explain the work on the exhaust side showing only the result, so I used some drawings. I was very very shy on enlarging intake ports in the areas where you don't need it. First, the main flow limit on the intake is the casting around the intake valve guide - you need to remove it, if you need more flow, and it's very very tricky to get the shape around the guide hole correct, because the burr tends to fall in the hole and you don't want it. Second, it's the bowl area, or the area around the seat. It's not round on a stock port! Air/fuel mixture can't flow from a square-shaped area into a round one without a significant loss, so you don't want the bowl area to look polygonal. I made it more rounded, but you gotta remember the most important thing ever - do not enlarge the smallest diameter of the seat! I.e. seat throat. You need it for the Venturi effect. The small radius on the nailhead is quite good, so it needs only minor rounding with a 60 grit strip. As for exhaust - it's awfully restricted, so you need to gradually increase the biggest radius you can get in the port. And shape the exhaust guide in a water drop manner. The central ports are restricted by the thick bolt castings. The area is a lot smaller than on the side ones. Combustion chamber enlargement is what you really need with bigger valves, and it's a pain to make. I can offer Nailhead porting services, if you want! Haha You can get it flowed afterwards. We don't have flowbenches here, that can show accurate CFM numbers, just some comparison. p.s. I might offer the actual heads for sale, because the owner owes me money for the engine... And he's not planning to bring them.
Cool, Do you have a background in engineering, so you can analyze all these areas and make the sketches, or are you familiar/experienced with engine porting in general, just by tinkering with cars?
Almost got my internal combustion engine design degree, but gave away in a favor of industrial design. I always wanted to make my own cars, which should've been the most beautiful and the fastest ones, haha. And so after I was done with engines, I've got onto design. I think, it's the design of cars - that what's all about. People get along with older cars, like Wildcats, because they look great! While older cars may be technically outdated, people still love them. So my point is that car design pretty much over car tech. If a car is very advanced, but doesn't look good (or very bad - I see a big trend for these in the past few years), it won't meet success. As for porting, I've read almost every book on head porting, trying to understand what it takes to make a better flowing head from the starting point, it took about 2-3 years of reading in part-time until I had actually seen and understood what's good and what's really bad. I'd say Bill Jenkins' "The Chevrolet Racing Engine" is one of the greatest books on the racing engine subject. However, a good engine is a combination of things. You can hardly improve an engine just by porting it, i.e. without changing other things. Unless you only work on exhaust side! Same goes for Chevy LS engines, even now you can get more power just by porting exhaust side (making bigger radius again, same laws). Intake and exhaust wave tuning is the real key to the power, it's not about a big lumpy cam! The camshaft/port style of a Nailhead is what gave the name to the engine. It's a little uncommon for a generic US engine of the time, but it's a more wise way to make a powerful and efficient engine. So the ports are small, the valves aren't big, how can we get a big amount of air? We need a wider cam, yet not a big lift! That trick works amazingly well on all engines with good ports. Say, 80s Toyota 4AGE (1.6L 16V straight-4) is very happy with 310/300 degree (advertised duration) cam with just 9 mm (0.354in) lift, it makes 160 hp with a big powerband on a bone stock engine (120-130hp stock, which was a lot in 80s for a 1.6L engine). The key is that you don't need a lot of lift! If the lift and ports are small enough, the engine would always want to breathe in air, even at low speeds, and that's what you really want! If you have big ports/big lift with long duration, the air would be slower velocity in the port, so the air would be a little "unsure" whether should it enter the cylinder or stay in the port, and that's what makes engine idle lumpy, ending up with a narrow powerband. And so 210/218 @0.050 in duration is not much for a Nailhead, and it makes a good driveable combination. Getting bigger valves will make them shrouded and you'd lose power, that might be a bigger case with Nailheads losing power, not a bad port work. I don't think you can fail much with port work, lol: the intake is too good to start with and the exhaust is too bad, haha. I don't see a way one could make them significantly worse than they come from the factory.
Been away for awhile and just seen this thread. It takes a lot of work to get past 225 com at .600 lift. Go to gsgtx. Dyno thread. We know the cam and flow numbers to see what that much air and cam at .50 does.
Bob! I was just thinking about you... Hope all is well. And of course it's easy to say now, but I somehow knew those videos were made by Whatever. Very cool, very informative.
Hehe, thanks! Actually these videos were published in the thread! But somehow they did not receive any feedback or comments at the time. Btw, I'm gonna add the rest to the thread soon, the engine was pretty much finished in October, and then the owner gone mad. So my point is to never deal with guys who may own good cars, but don't know a thing about them and what it takes to fix or make them better, i.e. with show-off guys from Moscow, lol.
Thanks for the videos and the contrabution the the nailheads whatever. Most of us love pictures and videos. Looks like solid advice to me. Once you get to a point porting on a nailhead you need a flow bench to get every bet out of it. Best numbers I have seen have been from the snake, really good to . 500 lift. You can see what 225 cfm at .510 lift does at 230 at . 50 duration. Tells us a lot , it's still needing lots more air
I'm happy to contribute something to the community! Here's the drawing, which shows the key difference on the exhaust. Basically, I tried to completely eliminate the second turn on the exhaust port. A major part of exhaust gases slide along the top of the exhaust port, so imperfections on the top are the most significant. I also made the headers to accept the new angle of approach, which points more downward (rather than to side as on stock engine). I'm not sure if this modification would give any readable CFM (though it should), however, I have no doubt that it would make an improvement on a real engine. I also managed approach angles on the intake, again to manage better flow in the manifold/port transition. Btw, I'm Alex.
the way it all came out, and a little more of the central exhaust ports [video=youtube;UbLZj_uEHjA]http://www.youtube.com/watch?v=UbLZj_uEHjA[/video] The whole stuff would be probably a lot easier to understand if you put your cylinder head against the video and compare.
Is the engine optimized, other than porting? Thank for sharing, will probely use your videos next vinter when my heads ( or some spares I bougth ) will get some attention together with the intake and probably a cam.. Would like the roller rockers, but they are quite expensive Houmark Danish member
The original engine thread is here. http://www.v8buick.com/showthread.php?270919-Da-Nailhead-adventures Since the owner was quite low on the money, I tried to do my best with stock intake manifold. The cam was TA's 210/218. I also ported intake and exhaust manifolds. Here's another little video on the intake manifold. Sorry about my pronunciation here, again. (At some points I can hardly understand what I was saying myself, lol) [video=youtube;E5Gd3XH0Yko]http://www.youtube.com/watch?v=E5Gd3XH0Yko[/video] I planned to do a second video on the intake, but, I guess, it wasn't saved on my phone for some reason.
By the way I just wanted to mention that the runner and cc molds in the picture are ported, not stock. Just in case someone might be taking a close look
Fair comment! I haven't noticed a big change, though it seemed to be not stock! As for 2nd turn removal - the force of high temp exhaust gases is much more significant when compared to cold air CFM measurement on a bench. The higher the temp - the bigger the force. Same law goes for exhaust header wrapping. Some books say that if you wrap the exhaust the tuned RPM will change significantly! So you'll need another length for wrapped exhaust headers, but the wave force, i.e. power increase, would be higher. p.s. The book: http://www.amazon.com/Scientific-Exhaust-Systems-Engineering-Performance/dp/0837603099
