David Vizard's PowerTec 10 EP 20 Power enhancing valve pockets
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- Опубликовано: 2 окт 2024
- In this , episode 20, DV explains how to not only check valve to piston clearance but also how and why reshaping them from a conventional shape can produce more power. Not mentioned in the video but pocket clearance measurements were preformed with solid tappet not hydraulic lifters.
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Back in the mid '80's I was doing cylinder heads and fly cutting pistons on a Bridgeport. NO ONE ever mentioned this topic ! I wish I knew these procedures back in the day , I would have been a hero ! Thanks David, it's never too late to learn !
Thank you David. Very well explained. Every little bit helps to beat the competition. Length of the videos never bothers me. You can not put a time limit or value on this information. People that want to learn will pay attention no matter what. Thank you Sir.
I grew up reading your books. I still have a couple stored away. And i still crack them open for more info. Thank you Sir.
So truuuuu 😂
Same here. Wealth of knowledge.
Have you done research on radius on the face of an exhaust valve with the unshrouding of the piston. Also what about 50 degree intake seats
Mr. Vizard I would like to thank you for all of the tidbits of secrets you are giving away. Alot of these things can be done without spending alot of money. My dad had me handing him wrenches when I was 5 years old. He used to work at General Motors back in the late sixties and early seventies. I was lucky enough to have someone like that to Mentor me into what I am today. My dad passed away 6 months ago. I wouldn't be able to be a good automotive technician if it wasn't for my dad.
David, I had the opportunity to meet you at the Daytona 24hr race where I had built a TR6+, We talked for some time because at the time I had a Speedwell Mini Cooper S. You sent me your first books and a few mini parts that were a bit non factory, we did well.
I came across your Power Tea 10 and Love them. I am going to see that my son and step son attend your classes and me along with them. This will be after I return from Vietnam. You Vidioes are great and please accept my graditude for the help in the past. I had been with David Piper for a number of years also, so have been involved in some serious GT Racing. Thanks Again.
Thanks David, invaluable information for enthusiasts once again.
A true professional and gentleman!
What I don’t like about it is that it’s not my engine your demonstrating on !😂
Thank you sir!!
You are the man Mr. Vizard. Once again thank you for sharing your knowledge.
Great video as Always. Could you please do a video about Long Rods vs Short Rods and the advantages of Each. Thanks again for making me smarter. And do you still have your Trans Am that you used in your How to build Horsepower books, it would be great to see it.
I have studied a bit about aeronautics. I have never considered the parallels in cyl head flow. I have learned so much from your videos. I am presently modifying a small engine for ultralight airplane use. Always learning from you, thanks!!
Hello, what engine did you modify? Thinking of applying some of David's tech to a 4AO84-4.
I like to have the block standing on its butt to install the cam. With the rear cam plug in the cam will not fall out the back. To keep it for falling out the front, a fender washer ususlly works for me until time to install the timing set. Once cam is in the block can be mounted on the engine stand. I have installed piston/rod assemblies on Detroit Diesel engines with the engine on its butt on a bench, when no engine stand for that weight was available. Put the cams in that way also. Detroit blocks need the rear cam bearings installed first before putting the block on pieces of 2x4, for clearance.
Thanks David, I really like how you continue to honor your daughter Jacque. Do you have a fund set up for the memorial you want to put up in her honor?
Thank you and God Bless, Tom
Thanks david
I thought you weren't suppose to beat on the crank thrust bearing.
Rolling those sharp edges also reduces the likelihood of a hot spot forming....One last thing....LS motor guys don't need to worry about valve to piston clearances....Just check out the cam recommendations on any LS motor forum....as long as you can spin the motor over after the cam install? YOUR GOLDEN!
Great information.
Love your work David(long time big fan), just hope that One day you Share some knowledge about VW 8v heads. Still widely used today in Brazil and México, but I do understand thats not your Core business.
I've bought some of your books not for my engine but because I love your work.
Good job.
A interesting video Sir. I have many of your great books. A pity you don't talk about 4 valve engines. I'd like to know how big should be the head ports in % of the valve diameter to get the best possible velocity.
Once again, thanks for the information
All these little 5 hp tricks add up, thanks.
Hi David, I have been your fan since the seventies when you were writing a lot of technical articles on Cars and Car Conversions. In fact I have your book theory and Practice of cylinder head modifications. Now at nearly seventy years old I have bought an MGC Sebring Replica which I intend to tune to nearly Full Race Specs. I wonder if you can do any lessons on this Truck Like 6 cylinder engine to try and get the most out of it. I am mostly interested in lightening of the crankshaft of this engine to reduce the inertia mass. I intend to port the heavyish head according to your 5 rules of cylinder head porting. The mods I am doing are the following. Forged Omega Pistons+H Beam Forged Rods+Kent 287 degrees cam with 11.57mm lift+Light Steel flywheel +3 x 45 DCOE Webers and Maniflow 6 into two into one exhaust. I will also be altering the distributor advance curve on a rolling road. Unfortunatel I cannot find a source for the Copper Lead Bearings so I have to fit the normal Aluminium /Steel Backing ones. Anyway I really would like to thank you very very much for your contributions in teaching people like us. THANKS AND GOD BLESS YOU. Regards Martin Spiteri, Car Clinic Malta.
One of the most knowledgeable guys in the head business and he says ‘I don’t want anybody criticizing me on using this hammer" lol. Nobody really has the right to say shit to you, unless it’s a polite question… screw them, don’t worry about idiots that take away that only thing to bash you. Your awesome and thank you for sharing
I'm a newcomber to your site, but have hand ported may and varied over about 40 odd years. Q. have you done a dyno test comparison between standard valve profiles, and valves that have been Back Cut? When I run seats, Intake particularly, I run them high on the valve at about .060" width, then back cut my valves to give me about .050" to .060" face below the seat. Any thoughts? A lot of my early port work was on 6 cylinder Holden heads, and various 8 cylinder heads.
I highly recommend anyone interested in building engines needs to check out all of David's books! I've used some of his tricks and they all worked. My favorite was the modified factory aluminum Quadrajet intake manifold.
THIS IS MY MOST WATCHED PROGRAM,,,,I THUROUGHLY ENJOY IT..... DAVID DOES A GREAT JOB ON DETAILS AND MANNER OF PRESENTATION .. THANKS DAVID,,,!!
Hey Mr Vizard i have the Parker Funnel Intake, when are you posting how to improve it flow by porting, Gino
Interesting, and makes sense: flame propagation is pretty much a fixed value, but piston speed being a variable things should behave a little differently at high vs low rpm. Does the general h.p. effects you found carry over from a 23 degree head to 18 [being less/more sensitive]? I have no dyno experience, so just for fun... I'm going to guess the 18 heads are less sensitive due to geometry being closer to parallel [and duck any incoming tomatoes].
Nice work as always.
Another great video. Love all your books. Do you plan to do any videos or more information about the A-series at all?
When deshrouding valve at piston Why do we loose power under say 2,500 rpm?.
I see there was no mention on valve to piston clearance, what is optimum, what is to much, what is too less, and what about side clearance ?
Thx David. Is there anything to be said about a continuous slot style valve pocket?
Thank you sir. I’ve often wondered about this and now I know. Also, there a perfect amount for quench area?
John, there is way more to the subject of quench than most think. It needs at least a 30 min video. I will get araound to this down the road in the 5 golden rules series.
This is also one I've been waiting for. Thanks David!
David Vizard Performance thank you sir.
Ever have any issues bashing out the trust baring on the main using a hammer to put the crank gear on?
There isn't anything that David leaves behind when it is time to make horse power...
Great job showing and telling,see ya next time see ya bye bye.and thanks
I’m having flash backs from the 80’s 😀, currently fixing to build one for a C10 Stepside 5.7 with a B&M 144, (looking at our notes from the 80’s and added things I’m learning from your videos.. thanks for sharing the info
Thats a mighty fine hammer your packin Dave
Another great learning curve for me. Just one thing I'm confused about is why was there some power / torque reduction at lower rpm (~2500rpm)? I thought the un-shrouding of the valve pockets would've given improvements across the rpm range?
My guess is because it acts like putting in a longer duration cam because you are getting flow over more degrees of crank angle.
Mr. Vizard, thanks for this video. This will help me with the engine I'm trying to enhance, the famously non-sporting Chevy 250 inline 6. I have many of your books, and am using bits from several of them to come up with a combination that will run decently well on 93 octane fuel, and be used on the street with some hiway. The "How to build horsepower" books (both the early book and the later one) have been great resources for me. Thank you for taking the trouble to write them.
David, I grew up reading any and all engine building topics back in the 80's, including your engine build guides. Back then I did something similar to the valve pockets as you have described here, but I did it for a different reason, I was trying to build swirl in the chamber. Today my ideas have changed a little and see that a inverted dome in the center of the piston to be beneficial. It was in one of your early books that you found that there was an power increase with a dished piston, this is what set me on this path. So I would have liked to see less depth in the valve pockets you show here (but still de-shrould the valve pockets) and then lower the center of the piston (put in a dish). This would make the chamber more detonation tolerant (thus allow for an increased compression ratio), clean up the exhaust stroke (less unburnt fuel mixture in the exhaust stroke), and allow a leaner full throttle mixture. The leaner full throttle mixture would produce more CO2 and less CO, then the combustion temperature on the power stroke would go up, the temperatures in the exhaust stroke would go down. The engine would produce more output throughout the torque/power curve with less fuel and less emissions at full throttle. Now David, this here is based on my work, (and not something I just happen to read in a book) and I would like some one of your caliber to give some feedback on. Thanks mate.
Excellent video and explanation David as always........thank you for the great information and back up to your awesome books....best regards
Excellent info as always David, but one suggestion: it would be good to caution that unless one is certain that no interference is present, the engine should be rotated very gently, feeling for possible V/P contact. Also one nit: at the 19 second mark, proven is misspelled... MB
I enjoy watching all your videos. They’re a great source of good information, that you’ve proven works for squeezing every ounce of horsepower out of an engine. Thanks for sharing! I’m always looking forward to seeing more!
These videos are awesome! I’m not in the middle of an engine rebuild, but it’s a wealth of knowledge that I will definitely use for my next build! Heck! I’m sorta looking forward to tearing my present engine apart, so I can use your expertise to help me make some more power! Thanks for all you do!
You know so many small tricks and stuff it’s crazy to even think how many hours you put into this! Thank you! I have one thing to ask you ? Will this trick you just showed help with pinging .
Thank you sir!
Awesome
What happened to the bowl mods?
I have an ooooold flycutting tool I got back in the late 70s, that has a 11/32 stem on it and it goes right through the valve stem guide of the head. I space a junk head up off the deck, and use it to center the cutter for the valves. It's all manual, and you have to be good at using it, but it still works in the engines that use the big valve stems.
Am I right that on a sub 6000 RPM engine that deshrouding just the intake valve relief will gain torque?
Thanks David. More good stuff, well worth more than 10 minuets. Regards.
Excellent video, again. Could the space between valve & piston be considered a quench area? Thanks dale
I really didnt like that there was absolutely nothing I dislike!
Thank you Mr.Vizard
David produces these videos to share his knowledge which is great but, it is also worth buying his books to get more information.
The gorilla wrench! Installs or removes about anything! @2:54, (the Hammer)
Really great that you are doing this. I had to remind myself how lucky we are.
Is this piston in the correct hole? Looks like it has the intake and exhaust in the wrong placement. I know it works for example.
Mr. Hawk eye Halbleib - that's exactly what I thought when I reviewed the video. The piston was a scrap one with overly large cutouts already,
@@marvingvx1 thanks for the reply, I seem to be one that looks at details like this.
This is an honor. I feel like learning from the einstein of mechanical and automotive.
_marvin put the translation in order not to lose details thank you_
thank you marvin
Audio sounds great in this video. 👍💪
Good - and Marvin and I really do appreciate the input to help us get our broadcast quality up to scratch. Keep those comments coming guys!!!
Thanks again David
Sometimes the simplest and most obvious things get left on the table...
This guy is a GURU of high performance V8's
Day number 2 of asking for a 4 valve performance series of videos.
--- and you are going to get just that but please remember there is only 24 hours in a day.
@@marvingvx1 I totally understand sir, please forgive my insistence I’m merely so eager to learn from such a legend as yourself. I’m truly ashamed to sound so insistent.
Like👍
Love these videos. Thanks for sharing.
@ 2:54 lol… DV trolls hater
Yep just destroyed the main thrust bearing in a 50K racing engine! LMAO That is the kind of comments I get all the time. I reckon they are from people that only read about building engines.
The Power tech hour!
Hint , hint, ha-ha, but for reals, I'd watch for a hour!
So would I!
You should get together with a CAD designer and design the perfect port, then look into making a full head.
Rusty, At first sight this sounds like a good move. The tech level in our shop is capable of doing such but the results will not be as good as a talented head design engineer. Computers are not intelligent - they don't do well at inventing stuff - yet!
@@marvingvx1 even with computational fluid dynamics (CFD)?
An evening with a pencil grinder . or do i grind up a radius cutter for the mill
That's a good question Dave. I have a bench top mill here at home. Don't think it's the way to go though. Because the head is fixed, and making a fixture to hold the piston would take about as much time. And I'm only interested in low end torque. So I think I'll just soften them up by hand. I've built a couple of 350's using the book ''How to build max performance Chevy small blocks on a budget'' By David Vizard, in the past, and have been very satisfied with the result. His porting book should be at my door tomorrow. Let us know how your method works for you plz?
This is the exact stopping point I'm at with my 383 sbc build. I swapped cams from a 110 lsa to a 106 and with an indicator my clearance is way too tight. I haven't checked with clay yet (building a garage to get the engine out of my living room) but I'll need to do that. I have the tools to perform the massaging, and that's the obstacle in front of me at the moment. Now I know what needs to happen.
Thanks Mr. V