David Vizard's PowerTec 10 EP 25 Vortec 5.7/350 Vs LS 706 w/o and w/mods, the best of basic mods.

In this , episode 25, DV investigates the advantages (or not) of going with the later LS 706 casting Chevy instead of the classic 350 Vortec Chevy. From there he looks into the mods needed to extract the most from the least work from the 706 casting. Though amongst the most numerous it is commonly considered to have the least performance potential. Here is how to make the best of a 706 castings with basic porting techniques. Including flow #'s, swirl, port energy, and Coefficient of Discharge curves
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[@michaelhargarten5118]

I like when David does the cut away of the cylinder head. It makes it easier to illustrate the work required to gain more flow, port velocity... The molds taken before and after the port job was a nice touch too.

[@boost1728]

Completely agree. It’s awesome to see where the material is thin from the factory so we know where not to mess with. Extremely helpful video

[@hydrocarbon8272]

The more you watch, the more you realize the best gains are usually at the top while the biggest screw-ups can happen at the bottom [right before the seat]

[@zAvAvAz]

. . He is the grand master.

[@paulseabrook8179]

Now we're talking. Cut-away view and molds

[@Just_someguy_2023]

David Vizard, you books are amazing and your videos are on another level. Your explanations over the years has improved my understanding and increased my love of motorsports! Thanks for all the things you do!

[@theoldbigmoose]

The information in the port castings was phenomenal!

[@daledavies2334]

77777778977777877777778977 08987

[@stephendennis7871]

David, as a Welsh Swansea boy and of a similar age to yourself and a big fan from the time I bought your book on modifying the Ford Pinto engine many many years ago it came as a surprise to me that you lectured in Swansea University. As an engineer I would have liked to have met you to talk shop. I am a big fan of this series you are doing and it's always a privilege to learn from one of the very very best in the industry and I wish you all the best going forward. Your current series is based on the small and big block Chevy and I understand the theory applies to all motors but if it's in your remit some comments and advice on European car engine would be nice to satisfy some of your British fans. All the very best from an old fan from Swansea. Stephen

[@DavidVizard]

Stephen -- yes the Swansea seminar was a blast - I am still in contact with some of the great folks I met. Thanks for youe kind comments. DV

[@mfaulks206]

@@DavidVizard I was there, wish I remembered half of what you taught, I can't make head nor tale of my notes now! Sounds like Stephen we'll have to make our way out to the US. I studied at Swansea Uni many years ago, fond memories indeed.. how little did I know best time of my life!

[@curvs4me]

Excellent! Floor hogging especially 24 degree heads is good for flow but horrible for power. Porters should always have a dyno mule to get real world results that your crazy system actually shows without it. Port energy, swirl, and efficiency are things that really give the true story on ports. I love these videos! Thanks so much David.

[@thomasleclair7418]

,,,,,,,,,,,,I think you just explained and defined the terms of port bias and design......................Love you......

[@mikebrown4429]

I’m working on an AMC 360 . I’m a rookie at this but giving it my best shot at head porting . I really enjoy your vids and have read a couple of your books several decades ago. Mike in Battle Creek Michigan

[@shaneshane1379]

Thank you sir. Remember, the majority of your students are not students at all, but the very few of them carry on with greater success. I have been building engines for over 30 years from heads up drag racing street car to dirt track engines. The limited stocker dirt engines have always been my favorite. No power adder, just skill and talent. The vortech head became a habit for me years ago. I'm now working with LS heads but my efforts are ignored by people due to the lack of knowledge they have. I can't say I'm the best, but I can say my work works! Your videos have energized me once again with that passion for gains. Because of you Mr. Vizard, I bought a 98 Chevy pu and pulled the engine. Vortech heads about to get some attention. 😁 Thank you

[@manitoublack]

"Bigger isn't always better." As a person who only ever really works with 4V Japanese heads with their steep intakes. Its always confused me just how 'low' the ports on American Push-rod V8's were. Especially on the exhaust side with the Pontiac V8's being the worst. Great to see a test to really prove the point that focusing on the port roof, bowl and seat is where the biggest gains can be had. Also showing that a good portion of the port floor on the very tall LS ports is basically just getting in the way. Keep the video's coming.

[@RobertBrown-bg2bv]

The cutter you use was Joe mandelos IFT 4529B-HP

[@RobertBrown-bg2bv]

Why are you so biased with your teaching

[@StuartBlake-iz6rf]

David very informative and your presentation is impeccable. Many engine guys are just swooning to improve their engines with all your information and know how. Thanks once again for your dedication.

[@mikedeal8659]

David thanks. Another great video. The amount of information and the way it was presented was outstanding. Sharing your knowledge with us is much appreciated. Looking forward to whatever you put out next.

[@BearFulmer]

Thanks for all you hard work and information you put on youtube

[@jmc6940]

Thank you for sharing your years of experience.

[@gothicpagan.666]

Would be fascinating to see the result of cutting away the valve guide boss to make it a constant radii and then fill the floor to make a 7deg taper all the way to the seat The more you learn the more you need to know.

[@landonthompson5604]

This information will be absolutely used on my 706 heads and I'm going to have a well running 4x4 truck after these modifications plus my 5.3 is going to become a 383 so the fun factor will be at a all time high. Absolutely brilliant!!!

[@Dane33781]

That's really cool. I've always thought about filling the floor.

[@jeffwooton7138]

So glad you're dipping your toes into the LS world. I have plans for a 6.0, with 706 heads. I've always wondered why LS cams ALWAYS have 4* to 10* more duration. Based on this video, you could almost follow the small block cam logic, and be successful. The caveat being roller cams. I do hope you shall dive into that soon. I truly like the idea of a square cam in an LS. I like torque! Please keep up the great work

[@derrelcarter9401]

I have always wondered why they have such wide CL and are Always split duration, always

[@indyrock8148]

The BTR truck cam is a good example of a single pattern tight lsa cam. Makes solid gains over stock everywhere. I too would be interested to see a larger say 220 or 230 square cam on 108 in a ls1 or ls3 etc.

[@jeffwooton7138]

@@indyrock8148, I'm sure they would rock. My thought process right now is 112/112, .585 lift, 109 LCA, with ICL at 105. I've been reading David's work for years. This cam falls in line with everything he has taught me. There was a shop out of Georgia, that built a Engine Masters build back in 2012. It was basically a carb'd LY6. Dang thing made 525 at 2500. Torque curve as flat as the West Texas plains. That's the numbers I like. I've got the build sheet saved, somewhere.

[@indyrock8148]

@@jeffwooton7138 I agree. I think say a ly6 lq4 etc with that cam would have the broadest torque curve from idle. And you know what? I bet peak hp would still be about 6000. Tires frying from idle forever. I think the 'traditional' ls cam is a response to two historical factors. 1) primitive tuning encouraging a wider lsa 2) early c5/third gen owners chasing chassis dyno peak hp bragging rights. This of course encouraged increased exhaust splits, wider lsa's Personally a cam I would like to see in an otherwise stock lq4 would be 225/225 108 104. .600 lift. I think that would be a solid min 500tq/500hp street engine

[@jeffwooton7138]

@@indyrock8148, I would agree.

[@mrvwbob156]

Have applied this great info to my 509 BBC, With DART 325’s ported at Racing Head Service I would love to send some CANFIELDS I have to you with the intake manifold Engine dyno’d at 790 hp at 7200 with a of the shelf ERSON ROLLER I see the Terry Walters builds and am always amazed Love going to school with you David

[@Between2Turns]

Superb content! I really enjoyed how thoroughly the concepts were covered and compared.

[@JaapGrootveld]

So there is a lot more to it than the fow figures show. Good to know.

[@jayramirez3646]

Thank you Mr.Vizard for another fantastic lesson, I will be applying these techniques soon. If you have the opportunity, could you experiment with the improved Ls3/L92 Rectangular port heads? Thanks

[@silentknight9509]

Would love to see you do an ls build David

[@gregsmith9457]

Thanks for imparting your knowledge. I look forward to each new video.

[@323gtx88]

Love watching a legend

[@323gtx88]

Sad at the end

[@avibuilt9]

Thank you so much for all your videos

[@joeyjojojr.shabadoo915]

The filling of the bottom of the 706's Intake port for an increase in top end performance coincides exactly with Chevrolet's own Cylinder Head basic port models for Gen3 and Gen4 LS motors, with the tall and skinny Cathedral Port being designed for low RPM performance, with the Rectangular Port LS3 heads being shorter, mostly evident at the bottom of the port, for more mid range with increased top end performance, with the more square raised port LS7 style intake ports being the shortest and widest for all out top end performance. It looks like the Engineers at GM produced solid OEM units with specific applications in mind.

[@marvingvx1]

Joey, filling in the port as shown here will increase output from, bottom too top of the rpm range.

[@idoewannautewno]

Thanks Mr Vizard.

[@StupidFastNova]

Another great video, thanks for sharing this wealth of knowledge

[@evanarthur7535]

My porting guy back in the day used to grind a “ramp” in the floor of the port to direct air toward the roof.

[@hazel-annpadilla9208]

Thats where the air flows, the roof. Thats why they keep raising the roof for more flow. Then fill in the floor for more velocity. Building that ramp, or some kind of directional airfoil, could have possibly caused great swirl effect if done right. Swirl is the greatest thing since bubble gum!

[@greatvaluewalmart]

Priceless information, thanks for sharing

[@BruceLee-xn3nn]

Great thing about 706 is you can find them all day.

[@bcbloc02]

Glad you included the dyno results because we don’t race flow benches. A pitty the dyno mule isn’t a more common cubic inch like the 346 as I bet the flow gains would show up as an even bigger effect.

[@marvingvx1]

Just hang around a little longer - doing a 331! The IOP predicted the output very closely BTW so given the data a dyno is not quite as important.

[@bcbloc02]

@@marvingvx1 oh don’t worry I am not going anywhere and look forward to each new video. 😎

[@nurbaini4308]

Best teacher

[@alisaculley603]

I wish I could afford for you to port my AFR heads. Thank you for the videos, your knowledge is remarkable!

[@mathewboyd3746]

Really enjoying everything about head porting here. Now to be able to translate this over to my model of engine (a NA 2 valve per cyl 4 cylinder engine).

[@DavidVizard]

Matt, what is it?

[@mathewboyd3746]

@@DavidVizard your probably not going to like it - Vw aircooled 2L Type4 base engine. The exhuast port is a real problem on these motors in standard form. It has a very tight short turn. But they are aluminium heads and getting performance valve train components is readily available now days.

[@gmh2533]

More great tech, Looking forward to seeing more head development and applying it.

[@marvingvx1]

Not sure I understand what you are getting at!!!!

[@duygukayhanisaskank4915]

@@marvingvx1 Hello Mr. Vizard, I have a few questions which may cause me to appear a bit naive.Never-the-less, I hope you will reply to me. More-so, I hope you will post an educational video regarding this specific topic. My questions: What does it mean when manufacturers of engine cylinder heads...such as DART, AFR, MBE, etc...advertize their heads as having a 9°, 11°,12°,14°,18° degree valve angle? I understand the valves are angled at that stated degree. But relative to what? Are both intake & exhaust valves angled? Also, what are the performance benefits & do steeper valve angles provide more power? I'm mainly concerned about aftermarket BB Chevy heads//engines. MBE claims a 9° valve angle provides optimum flow. My research shows their claim is correct. YES, I realize this subject may be complex to explain. But I'm confident you can present it clearly; as you do in all your educational videos. In my opinion, there are many people who don't understand this aspect of performance heads. Best regards, Ben

[@Poncho758]

David I’ve learned so much from you and confirms all my thoughts thank you

[@traceyturley1997]

Thank you for this info on ls heads. I would imagine a stock to mildly modified 4.8 or 5.3l truck engine would be incredibly responsive to use even for towing. Thanks for mentioning port filling to help port velocity and swirl. Most engineers or engine builders only want to focus on high rpm hp. It's awful hard to drive a dyno around. Improved torque and throttle response will really benefit a daily driver.

[@travispfannmuller7717]

Thanks for the great info, I'd love to attend one of your courses

[@MrChico809]

Another great video DV, thanks

[@modifiedmeansmorework1559]

these guys knows their stuff

[@ts302]

Thank you Mr. Vizard!!!

[@jorgegomez4608]

Excellent on port velocity with fill

[@renwickconolly2839]

Awesome video as usual sir!

[@b.s.adventures9421]

Interesting info as always.

[@sorensenperformance]

Dave the cutter your using and gave the Goodson number for is not a 39 seat. Its a 45 seat with a 39 top

[@martinzackery8377]

Great information! Thank you

[@MrSandRune]

Better,increased air.Watched "low-rev F1" motor,guy filmed down the air inlet.And it has a 2-3 mm noozle hidden inside the shaft.To build compressed air from atmosphere pressure.2-3 cm apart from carburettor needle.

[@petejoseph8257]

I always thought an LS3 head could really benefit from some floor filling.

[@derrelcarter9401]

Nicely done

[@gmcnelly2468]

DV: Found a goodson 4539 cutter (one for the exhaust; on for the intake; and one for the throat). Could not find he 4529.

[@ForneyRider]

amazing information. Really something.

[@383mazda]

I see a lot of porters eliminate the swirl ramp completely - what does that effect have vs only rounding it off?

[@wayneireland4802]

Thankyou for sharing that info.peace

[@camaroguy2919]

Awesomeness...

[@eliotbrown9662]

Thanks David!

[@vincebaxter6127]

I would really like to see a 30* intake valve seat and deshrouding both valves on a 706 LS head

[@approachingtarget.4503]

Its obvious why GM kept the vortec heads for heavy vehicles and used the fast burn on the performance models. Raised D shape exhaust ports!

[@jeffwooton7138]

A thought that has lingered in my head for quite some time. Say you were to perform the filling of the 706 "short side", and use a stock intake, wouldn't there be the required work needed to be performed on the intake? It seems that the matching of the intake runner to the cylinder head runner would cause a tumble, that would negate all the improve work. A venturi hump upstream in the intake runner could, in theory, introduce greater air speed, and, fattening the torque cure more. Or, am I just thinking too hard? A sheet metal intake is out of the question. Stock appearing, at least externally, is what I am after.

[@peterdarr383]

Yes - if you filled the floor in the head you would fill the intake some to match. Since he showed no increase in flow, just "efficiency", I really don't se the point for a street engine.

[@jonathanquell4760]

Hi David, What bore size was used when testing? Perhaps one that matched the 5.3 bore? We have heard that the 706 heads make more low and mid range power on a 6.0 engine than the 799 heads. If we used the 706 heads on a 6.0 with a larger 4” bore, we could further un-shroud the valves. The increased bore size of the 6.0 would have less cylinder bore shrouding. Looking forward to what you can do with 799 heads. Thank you for all your work and teaching

[@jonathoncouchey7151]

Thank you for posting this. Im gonna apply some of this knowledge to my 318. It has close chamber heads. Im looking for 350 hp

[@douglasnicholls1366]

The basic port smoothing Uncle Tony did on Lunar Outlaw's 318 should get you better than 350 hp, though the dyno test hasn't been done. David's work on this site goes well beyond that but also increases the risk of poking through to water on a 318. If you haven't watched the 318 build on Uncle Tony, you ought to -- he also covers specific issues with the 318 in his videos.

[@jonathoncouchey7151]

@@douglasnicholls1366 yeah ill recheck those videos, been qatching UTG since his first slant six video.

[@JackTrease16]

Just bought two DV books and really appreciate the content he shares with us. The guy is inspirational. One question… I was looking up that Goodson cutter mentioned in this video as I want to do a set of LS1 heads for myself. It seems it has a 45 degree seating angle and a 39 degree crown which is different to what I was understanding out of this video as DV was saying the 39 degree is the seating angle. Is part number IFT 4529B-HP correct? Thanks in advance if anyone can get back to us.

[@cdeprima1209]

Great job on all videos! Can you max stroker some SBC or have you already? Old used 4.125" strokes on some of theirs, possible? How about maxing out compression for NA engines, maybe need hotter cam to run pump gas? Thanks a million! :)

[@patrickwendling6759]

Thank you

[@perkinsrj69]

Mr. Vizard are you using the 39° cut on both intake and exhaust seats? Will these angles help even if the floor is not filled in? Thank you for the videos! Very informative and look forward to each and every one!

[@stooartbabay]

Hi David, Is there any chance you could do a video on the correct way to install a set of roller rockers? say a 1.6:1 ratio set on a BMC 1800 engine... getting the measurements and the shimming correct and also ensuring the correct geometry? I think that would be a great video and would also translate to other engines.. Thanks, Stuart.

[@rudyjhughes]

Hey David do you have any literature on building a flow bench ?

[@jackbell6364]

Thanks

[@juliodiaz8280]

Dumb questions What did you use to fill the port? What are the angle cuts you did to the valves?

[@tchinc6533]

The 4529BHP has a TOP CUT of 39deg. And still retains a 45 directly below.. Are you setting up the cutter to use the intended top cut as your seat face cut? 4529BHP 1.5mm 39deg 1.7mm 45deg 4.5mm wide 10mm radius. Is that radius on this cutter even engaging the seat at al?

[@DavidVizard]

TCH - yes

[@gmcnelly2468]

DV. My current project, and it is the first vortec/LS engine for me, is a bored and stroked 5.3. It comes in around 6.3. I am using the 862 heads that are very similiar to the 706s and have incorporated most of your recommendations, save the intake valve seat angles and the bottom port fill. Considering the increased displacment of my project engine, would you still recommend the port fill? By the way, the engine will be LPG fueled. Thanks and keep up the good work. By the way, the 706 heads made by cartech are prone to cracks with coolant leaks (lots of youtube videos on this matter and how to identify).

[@RobertBrown-bg2bv]

The color you use with Joe mondellos

[@billbraski2175]

This is s great video thanks

[@cstavro]

I really appreciate this video. I'm about to port my own 706 heads. I wonder why every port "guru" still flows the heads without blocking off the fuel injector notch. LS ports are rectangular, not "cathedral". Simply look at the intake manifold to see this. I ask because when I flow the head with the injector notch blocked off I see tonnes of turbulence right at the port mouth (and all the way past the valve). How does your port sound after this work? 4529b-hp isn't on the goodson website. do you mean 4539b-hp?

[@darrinstone49]

So the LS1 head doesn't like much porting unless you increase valve size & fill the port & intake manifold?

[@andrewnusroot2754]

10/10

[@justinmiles977]

Ive heard you reference the 39 degree seat a few times instead of the 45. Does this affect wear at all? Im considering trying this on a street car cylinder head.

[@MunsKi]

david wizard!

[@jims2286]

Vortec heads are getting hard to find at reasonable price are there any aftermarket vortec cylinder heads that are similar. in 2022

[@mikebell9166]

Thank you for this. It has helped me make up my mind what I want to run. It looks like a 4.8 is in my future, with some head modification. What did you use to fill the intake port lower portion? It looks like it could be either Devcon, or JB Weld.

[@DavidVizard]

JB weld will get the job done.

[@mikebell9166]

Thanks for your response; I truly didn't expect it! My 1st expectation to try was JB Weld, as that's what I have easily available, but it's nice to have that thought validated.

[@dalethomas9307]

So how is the longevity of the 39° seat? Is it going to last on a street engine?

[@tchinc6533]

I would think that its last even longer than a 45. It's the steeper 50/55 that degrade faster than usual

[@approachingtarget.4503]

More stable. The larger the angle, the more the valve will bounce. Think of it as sharp wood splitting axe. A dull 55° edge will bounce back. A 45 or less wedges itself into the wood. Same as a valve that is seated in.

[@superkillr]

@@approachingtarget.4503 You are mistaken. 55 is extemely steep and only used in very high end race motors. 30 is for diesel and junk gas engines and delusional 70's head porters.

[@DavidVizard]

@@superkillr - did you have an opinion here perchance?????

[@ciggs5649]

@@DavidVizard I don't understand this guy David. I've been building engines for 32 years sprint car mainly, stock cars, airboat, drag engines etc. I have never stuffed myself in a corner with 45-55 deg angles. I put every option on the table to achieve my goal and if I didn't we would run in the back of the pack. Round wheels are old too but the newest cars still have them. The English language was developed back in the 5th century yet that's what were typing here in 2021.

[@cstavro]

IOP tells me that this head is ideal for a 383. Why did you chose to make a 331? Do you think it will take advantage of the head?

[@stevedriver1476]

this is NEED TO KNOW stuff,, no good throwing money at it if its all wrong. 99.99999% of tech boards on the internet wouldn,t have a clue about the figures we just saw.

[@flowbenchdrama2233]

So to be sure on what Mr. Vizard is saying on the 39 degree seat cut is to cut your valve face also to a 39 degree cut also?

[@marvingvx1]

Yes.

[@crispychicken7933]

Great work! Any recommendations on the super common 799 heads? Something to be gained with flatter valves and porting or are these already good? I've seen many people on KZbin porting these and can't find anything from you!

[@DavidVizard]

Chris - will be covering that casting part #. DV

[@crispychicken7933]

@@DavidVizard Great! Also this might be a stupid question, but can you just cut any head that used 45° valves to 39°? Do you need a special valve or will any 45° valve grind to 39°?

[@performancenaveia7821]

marvin activates the translation so as not to lose details of the video thanks

[@spud4ever290]

DANG , missed it.

[@marvingvx1]

Marvin here. I can't find an option to activate, the only possibility is to transcribe the whole video myself buy my Spanish vocabulary consist of less than a 100 words? Wish I could help.

[@performancenaveia7821]

@@marvingvx1 video translation is ok, just turn it on Many thanks to marvin and david for their patience and attention.

[@jmc6940]

How do you make these molds?

[@mobil1super]

Hello vizard sir,. Please tell me how you made a intake mold shape , what material used to make mold ? Plz reply

[@johnpublic168]

How do you measure swirl or is it A calculated number

[@vikkilookwood7041]

goodson does not have that number

[@mikkokuorttinen3113]

What's the material used for filling the port?

[@1crazypj]

At around 12 minutes, (comparative port mould) have you filled roof of port?

[@marvingvx1]

No look again - the dip in the port mold is a bump in the port.

[@arturos.3973]

Like👍

[@Between2Turns]

What bore diameter was this flowed on?

[@user-gb8zp3zp1w]

port 16valve

[@johnsears4197]

ok

[@patrickmoore1017]

I still hate those LS thingies, lol.

[@remybrouwer8700]

Mr. David, do you have seminars as well for 4 valve cylinder heads porting aka Japan imports

[@marvingvx1]

Yes!