Here is a few pictures of some 425 heads that I am porting for my boat. Please excuse the untrimmed guides and unfinished chambers. Next week I will have them on the flow bench to get an idea on how well they preform. They are going to receive 1.94x1.50 valves. I have a couple of ideas and I was wondering if anyone else out there had tried them 1. Raising the exhaust port floor (this seems to work great on Ford 460's and 351C engines. ) Has anyone done it to a nailhead? 2. Same as the exhaust, raising the intake port floor to remove the dip and raising the roof an according amount. It would be limited by the water jacket but there is still a fair amount of material to be removed. Looking at the cutaway head I am thinking you could make a much straighter shot into the chamber. Much like cutting the stock intake flange off. 3. Switching to a 30 degree intake valve seat angle. Applying a theory from a different engine David Vizard gets some very impressive gains from 30 degree seats in an SBC head. If anybody has any results from my ideas I would sure love to hear about them. I will have some cfm numbers up next week and I am going to use some clay to investigate the raised port floor.
on the lower floor have you ever tried to create a rymth section similar to a cnc set of heads. if you have access to a smoke machine you can see it create the turbulence and make the air move up off the floor and into the air stream that is coming over the dip?
I have never experimented with port texture, I did read an article a while back that stated polishing the CNC finish off exhaust ports on some AFR 190's yielded a 5 cfm gain across the board. On the intake side they advised to leave the CNC finish as it helped with revision.
Finally! You've got a head to split! That's pretty interesting! Can you show the thickness of the combustion chamber wall near valves. That's a crucial info for unshrouding. Do you mean that you want an all out head porting? The upper curve of the intake port is made like that to easy up technological aspect of the head: it's easier for production with a 45 degree and easier to service, when the surface of the intake flange is parallel to the engine, when the head is intalled. And so the curve is made to have a smoother transition from the intake manifold, which has the same curves inside. So if you want a more straightshot intake port, like the one you drawn, you'll need a new intake or an extensively modified stock one. Again, according to David Vizard, the air has no restriction if a curve has approx 3 inch radius. So there maybe no actual reason in such a straightshot, and so the curves inside the intake manifold would have more restriction than the actual port.
487nailhead, you are thinking in the right direction.:idea2: You will have to do extensive ssr work to get any good results from what I have seen:grin: The intake manifold is a big bottle neck. I was flowing the heads with the intake on to see what kind of restriction there was. We are talking small amounts of air. I am going to be trying a couple of new ideas this coming winter, first I want to see how the work I did on my heads reacts on my car. Should be next month. Also look at manifold comparison thread. Also gsgtx just dynod his nailhead with a ported factory 1x4 intake and got 426 hp and 549 tq. I am going for the straight shoot path way and seeing how it works. You are going to have to slow down the velocity at the ssr or you will have lots of turbulence.Good luck
When I was analyzing my cutaway head last night I wasn't thinking on how the intake manifold reacts with the port. Trying to remove the dip from the floor would more then likely damage flow. I am still optimistic on the raised exhaust port floor. On my test head (the one I cut away) I had the combustion chamber opened up to about 4.060 across, it did taper at the bottom by the valves slightly. The scribe line around the combustion chamber in the pictures right now is 4.250. I will drill some holes in it and get some thickness measurements. For an intake I was running a completely stock B262. The flow bench I have access to has the provision to do wet flow so if time permits I may run a wet test with the intake. What form are you using on the SSR? I am always really cautious when reworking, many years ago I lost 18cfm across the board on a pair of small block Ford heads from what I thought was a great form for the short side. 15 years ago Ed Mosler (Formerly of TA performance) had a shop here in town. He was a really nice guy, taught me a lot about porting in general. The form I have on the short side now is a duplicate of the heads he helped me do years ago. If someone has learned something new I would love to see it.
Looks like good porting work. If you were lucky enough to have Mr Mosler teach you nailhead tricks I would stick with that. I would love to be able to talk porting with him. :TU: I just play around with this in my shed. The wet flow stuff will be great to hear results:TU: Also just wondering what your mcsa is. Thanks, Bob
I was just at an instructor seminar and this came up and we plaied on the flow bench with it. try finishing your intake port 120 grit 220 grit and watch the difference in the turbulence. we finished a exhaust with 80 to create good turbulence. not all turbulence is bad and making the air move into the air stream by using turbulence was pretty cool.
What you said about turbulences along the walls due to rougher finish improving flow makes complete sense to me. Several years ago I was watching a video online of a SBC cylinder head on a flow bench. I cannot remember where it was but the air going through the head had a blue tint through it, midway through the test they changed to red tinted air. Almost instantly the air movement through the center of the port changed color, what was really interesting to me was that the air on the roof and short side of the intake port remained purple. Another article I read on Joe Mondello's website talked about port finish, he recommended 60grit finish on the intake side to "hold air in suspension". Prior to this I thought that all air moved in the port at all times, but according to him air sticks to the walls of the port as the engine is running. My heads are initially finished to 60 grit on the intake , then I do a light polish with 36 grit paper of a flap stick. On the exhaust I finish them with 125 cartridge rolls then 60 grit flapper. I do not have any formal training on porting but when I first got into porting heads about 15 years ago I was warned that if you see a strange bump or curve in a port leave it alone because it is there for a reason. I think (mind you I do not have any proof) that the small lip that rolls up at the end of a nailhead exhaust port is to create turbulence and push airflow back up towards the roof of the port. If I am correct then building up the exhaust port floor to remove the dip after the short side radius should keep air movement close to the port roof and eliminate disruption at the exit. We'll see, my valves will be here Monday and I should have them up on the flow bench by Wednesday or Thursday.
Looks like very nice work! I've done head work, but without the use of a flow bench, I stay conservative on the mods. Bob is one of the few here that has done lots of flow testing. TelRiv (Tom) has worked with guys like Mike Lewis to produce NH heads that work. Greg Gessler is another well known NH porter, but doesn't post here much anymore. There was another guy here, from Mondello, that was doing some experimenting. If I had my own flow bench, I'd probably make some molds of the ports , then make some plaster replicas to experiment with. Interesting stuff, keep it coming!:TU:
:TU: exactly!! Bigger ports are not better and it is more important to promote mixing of the air and the fuel and ]increase velocity of air through the ports. I call it the pelota valve that we used on the flow bench but we would introduce smoke from the evap machine and you can see the magic happen. one thing I found interesting is how the formula for intake plunem volume and the nailhead is way unday size. That's why the carb spacer makes them up . Your going great work and cant wait to see your work Paul 66larkgs
If raising port floors were the big thing the old timers would have already figured it out. These heads are not chevy or ford. Not a Whole lot you have to do just port matching and bowl work, take down the short side radiuses and valve guides , polish the exhaust and chambers with a bigger intake vlave with a good 3 angle should get good results. Check out the thread http://www.v8buick.com/showthread.php?265921-Ported-425-heads-flow-s
I know I am not working on a Chevy or a Ford head; I’ve been porting those for 15 years. There is no R&D left to be done on those engines. ou: The entire reason I started this thread was to seek out some information about what other people were doing, and if what I was attempting had tried and failed (or succeeded). I spoke to Mike Lewis (lives here in Fresnoand is a very renowned Nailhead porting guru), he has never attempted raising the port floor or changing the face angle. I called Tom Telsco and he as well had never attempted the modifications I am working on. I never did contact Gressler but I have heard they are out of the porting business. I don’t think that any of the old timers ever even tried raising the floors. When nailheads were being raced in the 60’s port design was not that advanced. A Nailhead port floor takes a sudden drop after the short side radius while the roof remains level. A 455 Buick and nearly all V8 Oldsmobile engines do the same. At that drop airflow begins to break away from the floor and create turbulence. On Oldsmobile and 455 Buick heads Joe Mondello and Edelbrock both raise the port floor, if I recall correctly Mondello claims a 15hp gain by raising the port floor level with the SSR. I did look at your thread Snake and I have to tell you those numbers are AMAZIANG! :TU: They are up 10 to 20cfm across theboard from anything Lewis, Gressler or Magnotti have done. I think I might pee my pants if I could crack 230 on the intake and 150 on the exhaust, but you’re already there. Congrats on your port job, they sure look shiny. :grin:
Sorry for being to blunt, but I have saw some of Modellos old work on a nailhead, not sure where now? but he actually broke into some bolt hole bosses creating more flow hogging out, I was lucky in the selection of the port runner, but the Guy flowing the heads chose it told me to do some extra work in certain areas before he flowed them. Im sure all the ports might average out to good numbers, but he didnt do all of them just a couple and had me use as a guide. His father ( Charlie Slover) passed the buisness down to him ( Michael) he is 50 yrs old and has been taught since a youngin. He liked what I did and knows I have alot of hours into them( probably 60) he has experience with alot of heads and how to make them flow. He remembers little on Nailheads but said his father knew alot and specializes in big block Lincolns. His father was doing alot of the Rods in the day and Isky recommended him.
Greetings. I own a set of "D" heads where the roof of the exhaust port is raised and regrettably the floor of the port was lowered. When Ed Mosler checked out my "D" heads some time ago he agreed that raising the floor of the exhaust port would achieve more flow................"stock" head or "D". The major problem would be.....how do you raise the floor when the port is so long? In fact, while I was at his shop he was welding up the exhaust port floors on a Ford head. I guess the alternative to welding could be a "port plate", or some tongue from the exhaust manifold to raise the port. On a 401 nailhead, Ed flowed a cylinder head with the exhaust manifold sitting higher than the port floor (enlarged bolt holes) and picked up some flow. You are correct.................raising the floor works. Marty
Is Ed still around and porting, If so where? It has been at least 10 years since I have seen him. A friend of mine told me that he had a stroke, and I was not sure if he was still porting. If you could please send me his contact information. If you look very close at my cutaway head you can see it cracked during the brazing, I had the entire head pre-heated to 600 degrees and it still cracked when cooled, It's too long of area to braze. A few years ago I discovered a single part high temperature repair compound called Thermosteel. It is rated to 2000 degrees and I have used it to fill heat crossovers in several different styles of heads with great results. Assuming I see the gains that I am thinking I will see in raising the floors I am going to use this compound to do it. I have already used it in the two center cylinders to fill the heat port and reshape the bowls to match the two end cylinders. I don't think that they are going to make the flow bench this week. Possibly first part of next week. Still trying to get the boat back in the water by Labor Day.
Good morning. My last contact with Ed was when he was still in Fresno. My understanding was he moved to San Diego................I do not have any info on him. Please let me know your efforts with Thermosteel. Thank you, Marty
Ed is still alive and living in San Diego. He has not done any head porting in years. His mother passed away about 2 years ago. He lives near the boarder of Mexico near Crower. I would have to get is ok before giving out his number. The one set of Nailheads I ported I was able to get 241cfm out of the intakes, don't have the exhaust on my mind any longer. I have always said after that job, that every wannabe head porter should be required to port a set of Nailheads. To get a nice radius on the exhaust ports I remember having to sand it with emery sand paper. Wore my fingers out.
I am looking forward to 487nailheads results. I think most people in the know agree that cfm on a flow bench is not the end all hp and tq indicator. But on a nail head it is so starved for air for the C.I. is why it falls off like it does. Cross sectional area is small and speeds over ssr are very fast and ssr is like a drop off. Air crashes and stalls on a stock runner at around .450 lift or so. I found the more I played with the ssr and a little more air was let in I was getting higher speeds at ssr. When I finally got what I think was right velocity wen from 390 to 420 along ssr to 350 to 380 fps. Now my test head is very quiet all through the lift range and at .700 it still went up to 253 cfm. That is the highest lift I tested at. I did open the runner a little bigger than gasket match. My mcsa is 1.92 sq inch. 11/32 1.94 valve I have a few ideas I was gonna try this winter, one was also playing with filling the floor and raiseing the roof some. Same on the exh. side. Good luck 487:TU:
