Think about how an engine works. 150pds, HA what happens when the air/fuel mixture fires. Thousands of pounds???? The valve opens while the fuel/air mixture is still expanding to let the exhaust out because another cylinder of the eight will be producing power over the one that just fired. Now, how efficiently the exhaust goes out is another story. In a normally aspirated situation the intake is the PROBLEM. In a pressure feed situation the EXHAUST is the problem. I know all the old sayings say it was an exhaust restriction. Today we know better. The more fuel & air you can get in on the intake stroke, all other conditions being equal, the bigger the explosion, the more POWER it will make & the spent mixture will have MORE pressure behind it. It has to go out, it has no CHOICE!!!!!!
If it makes you feel any better the last picture in the auction has a broken valve guide. Years ago someone on the board was swearing to NEVER replace the valve guides. He was saying the valves would not seat properly again. o No: Are the valve guides still available or can you pull one from another set of heads? RIck
Ford, at least, agrees with you. EVERY FE-engine exhaust port except the SOHC shares the same archetecture; including the huge-ass Tunnel Port and similar exotica. I'd like to see the exhaust flow at least 80% of the intake port; if it doesn't you have to add exhaust duration that bleeds off cylinder pressure and increases overlap. Wasn't Buick known for longer-than-typical exhaust duration camshafts in the Nailhead era? I seem to recall that they had some rough-idle troubles in the late-50's--early '60's that took a cam change to cure.
Valve guides are easily replaceable. Press the old one out, press the new one in. They're only about $3 each. I just had my heads done. Some of the original guides had the valve stem hole off-center by 0.012"! Machinist said he had no problems cutting the fresh valve seats. Those eBay heads had the flange cut off with a bandsaw. They still need to be properly surfaced by milling. Should be easy to duplicate for what the eBay heads sold for. The BIG question is....will they flow better????
On a more positive note Street Rodder Mag in the Nov. issue has an article about "NailHeads" & mentions my Mini-Starters & Adjustable, Variable Ratio Roller Tip Rocker Arms". An eight page spread & an article about "TV" Tommy Ivo.
Valve guides ARE replaceable. You must remember to knock them out from the valve side up not from the top down. You need to be careful with some of the replacements as they don't have a tight enough "Press Fit" & are prone to falling out. Best to measure old & new beforehand. The "Nails" wipe out guides pretty quickly because of the side loading caused by the short, stubby rocker arm. Add a "Hi-Lift" cam & it makes the problem worse by many fold.
Yeah they'll flow higher CFM but that is not the holy grail that the average joe believes it to be... You can make any hole flow more by making it wider (or shorter)... but by doing so you move the peak HP RPM higher and higher (likely way past the Nails intended RPM range) If you put a fist size Top fuel port on a 400CI street engine you'll have massive CFM numbers, and an engine that wont idle lower than 3000 RPM's and wont make any power until well after the stock valve train and reciprocating bits gave up on you and headed for the oil pan... The Nail has massive low RPM torque... because they designed it to. Those ports are the reason why a Nailhead makes better torque than a much larger big block. Trust me even in 1950 Engineers understood that the shortest distance between two points is a straight line... They didn't put curves there because they were tards I'm sure that drag racers spinning the nail up to 8000 RPM's didn't care about torque at 2000 RPM's... But if you drive yours anywhere but the strip this mod is like nuetering your Nailhead. This guy has low torque: :3gears: This guy has a factory stall torque converter and cut the intake ports apart::idea2: o No::ball: Anyway I don't mean to preach like I'm the worlds Nailhead expert I'm not, but I do know that most engines don't make torque like the nailhead and that's one of the traits that make the thing so cool.
Buick exaggerated quite a bit about the nailhead's actual output. read both threads, which include the buildup of the engines.. http://www.v8buick.com/showthread.php?t=152669&highlight=dyno http://www.v8buick.com/showthread.php?t=115156&highlight=dyno barely exceeded the factory's advertised output.. so you may be killing the "advertised peak torque" by bumping it up a bit in the RPMS, but you may be improving it across the entire rpm range in the "actual torque output" so the "numbers" might be hurt, but you may improve greatly in seat-of-the-pants as well as actual ET'so No: :3gears:
I'm not disagreeing with anything you just said I read those threads a while back myself (I posted to the second one) and still came away impressed for a few reasons. Anyone who doubts that CFM is not the be all end all; should ask themselves why a 2X4 setup made less torque and HP than a single four.... I'm not surprised. But among the old school muscle car guys the dual quad is king, despite the fact that most racers run a single 4bbl... Lazy ports are just as bad for making power as lazy carb venturis, and both are caused by too large a hole (or to many holes in the plenum in the case of multi carb setups) air velocity is important,... and those long Nailhead ports were engineered by smart guys, who understood that 430-450 foot pounds in a nice flat curve from off idle to 5,000 RPM's accomplishes far more useful work than 40 or 50 extra HP from 5,000 to 7,000+ RPM;s More than 1 foot pound per cube is impressive from a gas engine designed in the 50's, hell its impressive by modern standards... The Chevy 454 has 50 cubes on the 401 and doesn't manage over a foot pound per cube, with pretty similar factory horsepower numbers. Factory numbers had multiple methods for calculation, Buick's were "net" if I remember correctly... Which basically means best case scenario. Most engine dyno's these days calculate "gross". That alone will lead to discrepancies. Extrude honing is no substitute for flow bench guided head porting. I would never extrude hone a head port, you may make the port lazy by taking out metal where the air velocities are already low...
OK. I gotta chime in here... If for nothing else, the knowledge gained (for all of us!) by the "Rotted Honda" idea is worth persuing. I, like many others, have been looking for ways to clear up the "bottlenecks" in what has been coined the "asthmatic" nailhead. Intake runner LENGTH is responsible for torqe RPM! Make it flow faster by straightening it out, porting/polishing, or taking out inherent casting flaws, should only improve on the design. I refuse to be believe that an engine designed so many decades ago can not be improved upon today using modern principles and technology that was "voo-doo" science in the 50's! A person can get a lot out of the comparisons of the diffferent aftermarket intakes I tested to prove this point. It was hard for me to judge where to go with my build because there is so little data to draw comparisons from- only theory and listening to others perceptions and opinions of what they have done. I for one, will listen and pay attention to hard data over conjecture any day. Yea, I just broke over factory numbers on a modern caliberated dyno. Crazy that I'd like to know what a stock build would produce. SJ- Im a little confused by your statement: a 2X4 setup made less torque and HP than a single four...." What are you referring to? Erik
First off, I've never even SEEN a nailhead head, so I don't have any real experience with them. That said, the logic of working the ports seems backward to me if they are anything like any other typical factory head. The ports are usually the last place to find air flow. Bigger valves and the bowl area seem to be the places to start, and only then are the ports worked to provide as much flow as possible while maintaining high velocity. In David Vizard's series of articles on head porting, he points out the fact that, for the biggest torque for a given compression ratio, the valves need to be as large as is physically possible. He dismisses outright the notion that smaller valves produce more torque. Seeing that these are Nailheads we are talking about, I can see the risk of getting the ports to flow a large amount of air, only to be met by the restriction of the small valve size, and in the process losing all velocity and ending up with a head that has worse performance overall than a stock head that has been ported in a more conventional way. http://www.gofastnews.com/board/tec...chool-5-identifying-primary-restrictions.html http://www.gofastnews.com/board/technical-articles/1130-porting-school-7-power-port-volumes.html ________ Kids Wellbutrin
"The ports are usually the last place to find air flow. Bigger valves and the bowl area seem to be the places to start, and only then are the ports worked to provide as much flow as possible while maintaining high velocity." This is true to the nailheads. The bowl and Valve are CRITICAL to flow! "In David Vizard's series of articles on head porting, he points out the fact that, for the biggest and widest torque curve, the valves need to be as large as is physically possible. He dismisses outright the notion that smaller valves produce more torque. " This isn't entirely true; looking at todays Big block Chevy's. Of course, Vizard is making a general point. Again, lets remember that it's not all about the numbers. I can make any SBC show big numbers but the driveability and the practical use can be thrown out the window for 20 minutes on the flow bench to show some big number on a piece of paper. Back to the topic at hand. I have my test head in the mill right now and am slowly working down the flange. If all goes well, I will have some quantatative numbers about the middle of next week. And Could I test that Algon on the dyno with my 364? :grin: Mike Bangin' away
Can't wait to see the results! I had to correct what I said above after re-reading the article. He doesn't say anything about the widest torque band, but is speaking about the most torque within a given RPM range. from: http://www.gofastnews.com/board/technical-articles/1247-porting-school-8-optimal-port-areas.html "The first and most important of factor is that if we are seeking to make the most torque from a given compression ratio over a specified rpm band then the valve sizes needed are the largest that can be installed without incurring a mechanical problem. I make the afore mentioned point because there is a misconception that if torque at a lower engine speed is the goal then this can be had by using smaller valves. I recently was talking to a seriously good head designer who had the job of developing a cylinder head in terms of flow where the customer had specified he wanted valves smaller than usually used so as to make more torque. My seriously good head designer did not have the heart to tell this customer that what he needed to do the job was smaller ports not smaller valves. Still on the same subject the Avenger engine I did for Chrysler that had a power band from 400 to 8000 rpm had valves that almost filled the cylinder. This car drove like it was powered by an electric motor rather than a gas burner. OK so rule # 1 here is that if you are seeking to maximize output over a specified rpm range the biggest valves possible are where you should start. From this point on it?s a question of port area and cam selection. " ________ ARAB RECIPES
Thank you! That David Vizard quote should speak for itself. I'd recomend reading his books to, but his porting school articles on GFN are incredible and free. Its amazing how fast people on the various automotive forums I read are finding sites like speedtalk and GFN... I'm damn curious what the results will be too, but I think a big loss of low torque and a big bump in horse power high up in the RPM's with a very peaky no longer flat torque curve, is a safe bet... I'm betting torque lost will outnumber HP gained by 2 to 1, unless the experiment includes an amazingly well designed sheet metal individual runner intake. If you make the ports TOO big or short you will put peak HP RPM up into the 9, 10 or even 11,000 RPM range, and you'll never see it. Or if you do you'll only see it once :eek2:.
Oh come on man!? Are you serious? Voo-doo? :rant: You are talking about the generation that won WWII! Made the atomic bomb! How about Jet fighters? Do you know what the SR71 Blackhawk is? Guess which generation of engineers built that? NASA... Man on the moon... I wont dispute that the last couple decades aftermarket products have come a long way. I will be happy to argue why though... Mostly it has to do with the industries (the air flow side) early products often being power losers, that did a poor job at anything but wide open throttle down a drag strip... Not until OEM engineers started coming over to the big aftermarket companies did they start designing things like the Edelbock Performer RPM Airgap intake... Or AFR Heads... etc. Look at the stock cast iron "voo-doo" technology Nail intake. Hey wow that thing looks just like a Performer RPM made 40 years later! Holey crap... split plenum, AirGap design, long rounded smoothly curving runners. Ask yourself why fuel control ribbing on the bottom of plenums are commonplace on OEM manifolds but haven't shown up on "performance" aftermarket designs until many years later? I'm not saying it can't be improved on, I'm saying its a very smart design that does what they intended... It makes more torque at 401 Cubes than a MUCH larger big block. The first link Jaybird posted shows a 2X4 dyno'ed after a single four barrel on the same Nail. Unless I misread it? Seriously man I'm not trying to be a dick, I just think there's a point to be made here that may keep some guy with a street driven nail from cutting the balls off for HP he'll never rev to. I've said it already if you're building a drag car knock yourself out... But realize the SBC became overwhelmingly popular and knocked the nailhead off the top of the hill for a reason... If you want to rev to 8,000 RPM's and make 500hp at 7500... there's a much cheaper way Either way be prepared to lose big at every stoplight to even a garden variety Nailhead...
I think this quote sums up what I was trying to say: "Before winding up this feature there are two points I want to make clear. First that a port a little too small will be a far better deal to drive than one that is a little too large. 20 cc extra in a small blocks intake port can easily cost 25 lbs-ft and sometimes as much as 40 lbs-ft at a point in the rpm band that is most often used for a true street driver. Also a port that continues to increase in flow at more than say 0.050 above the maximum lift that will be used shows almost conclusively that the port is too big. That is a real mismatch of port size to cam/valve train spec." from http://www.gofastnews.com/board/technical-articles/1130-porting-school-7-power-port-volumes.html I agree with the others here... this will likely not be a good thing for a street motor running at low RPMs. ________ Tube ****
Hey SJ 66 Lark. If you are going to rant at someone else at least get it right. "Do you know what the SR71 Blackhawk is?" I guess you don't. It is a SR-71 Blackbird. http://en.wikipedia.org/wiki/SR-71_Blackbird
In looking at the shortened intake ports, it appears the biggest advantage would be that we can control (with intake manifold design) the entry angle of the inlet charge into the bowl....that characteristic alone may make the Nailhead bowl and valve design flow much better....or screw it up totally. Only testing will tell for sure. Mike....what will your flow testing use for an inlet to the port? will it be anything that resembles am intake manifold port? Do you feel the entry angle to the port can significantly vary the results? With the proper intake manifold design, we can use smaller runners to keep the VELOCITY high to produce good torque, and (hopefully) the revised head will flow more VOLUME to produce good hp numbers at higher rpm. Hmmmm...I wonder if the exhaust flange can be milled???:Brow:
Okay you're right, to have an opinion I must be absolutely perfect and infallable... LOL whatever, blackbird sorry, I've got that Jet on my Licence plate you'd think I'd remember that. The point is 1950's engineers weren't toothless hillbillies who put S curves in the intake track because they were too stupid to know a straight line is shorter than a curved one.
The original 322 had a shorter deck height than the later 401/425.....I wonder if they had to angle the port up to clear the valley pan? Or maybe they went with that design so they could machine the valve cover and intake flange in one step. That would save some bucks on each head, and we know the bean counters often had priority over the engineers and hp figures!
