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Thread: Down draft b.v. Pinto with variable velocity stacks shed build adventure

  1. #41
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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Are you sure you need to offset your exhaust guides by 1.10mm sounds like a lot of offset with 46 and 37.5mm valves, that is equivalent to 45.4mm and 38.1mm, GRP2 inlet and GRP1 exhaust, what cam are you using and what is the valve lift at the point where both valves have equal valve lift?

    I imagine offsetting the exhaust valve 0.50mm away from the inlet along the length of the engine would create room for a 47mm inlet / 37mm exhaust combination

    Hmm, maybe there is an issue with using a 1600 head (and a cam with high overlap) with its 2mm longer valves being closer to each other, like a 2.0 head and both valves at 2mm lift if you know what I mean, if this is true it would make a pretty large difference to overlap clearance with long duration cams + big valves over GRP1 size
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    its a good question...the answer is i still havnt decided on a cam...so i have made some worst case measurements..both valves at 5.9mm lift =0.8mm touching..6.4mm about 0.9mm touching....i could have my measurements wrong ..then i added some wiggle /clearance room...hence the final figure...if i could move it just 0.5mm it would make life so much easier...
    i have considered making the exhauste valve smaller say 36.5mm and moving it0.6mm this would be the simpleist route(in reguards to rocker ball stud position)...

    the bottom end is a long rod 143mm and 92mm (23MM CH) pistons 80mm stroke about 2133cc ( so need a cam to suite the head and bottom end combination) I am still trying to get my head around cam spec requirements for what i actually need...

    mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Jason ..i have looked at my figures and i can see i have doubled the actual events.. my original measurement 5.9 valve tdc =0.8mm actually should have been 5.9 valve tdc = 0.4mm ...and 3mm lift a tdc = 0.00 clearance......i am still not sure what the maximum valve atdc would be...but if i can move the exhaust valve max of 0.4mm it will make life so much easier with alignment...
    measure twice and cut once...

    cheers mark

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    Racer Decade Plus User RWD fords rule's Avatar

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    The max overlap I have measured when using short valves (that give similar geometry to std length valves in a std head) is around 4mm each valve, GTS4, there is no cam that I am aware of that has over 5mm lift at TDC, if using long valves the overlap lift gets much higher even though the peak valve lift is lower due to tilting the rocker pads closer to each lobe on overlap, shorter valves = more lift and less overlap, same result for each valve inlet & exhaust

    Here is the GTS4 vs a secret rally profile

    I think you could not go wrong with GTS4 with your CC, TB's and super flowing head, true net inlet lift was 12.95mm, we can discuss other options if you like

    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Thankyou jason..i did compile a list of availabe cams...gts6.gts4.piper 320 ,rl31 ph 6 ect ...but the truth is i have no idea what cam would actually work..
    i am also running 8 injectors..your experience would be appreciated ...cheers mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Out of the kent selection GTS6 would be my preference for racing, 296* quoted, around 13mm true valve lift with lash and the valve lift at tdc isn't too excessive either which would be a bonus for your engine, around 3 to 3.5mm equal lift, I don't rate the newman cams tbh all have huge overlap lift, ok with injection but not carb friendly, piper have mostly a small selection of old profiles for the pinto, kent are best off the shelf imho, not mega powerful cams but they have a decent selection to choose from

    About the valve sizes, a 36.5mm exhaust will get the job done
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    I like the look of the gts6....until i decide on cam i will put the exhaust valve position on hold...

    so decided to modify the throttle bodies...

    there are things that need to be changed
    the injector angle
    the outlet side bore size
    the outlet side bore taper angle
    the outlet side bore taper position
    the inlet side bore size
    and the inlet side taper



    i dont have a 4 jaw chuck for the lathe ..so used a spacer on one jaw of the 3 jaw chuck...set taper and worked out the offset(take more material from the injector side of the throttle body

    before outlet side


    and after



    you can see the offset taper here


    next i wanted to change the injector spray position
    before


    it sits in a 16.3mm counter bore
    so hand ground a 17.5mm drill to 16.3 and ground it flat bottom..cuts ally ok..
    after


    the injection body flange gets in the way at this angle so a radius was cut to clear the injector



    all 4 now done
    checked the butterfly for size while it was to hand 45.95mm (46)


    these injectors shown will be used as the lower 4 for the lower revs

    because my throttle bodys are spaced at the stnd inlet spacing i will use a modified pinto injector rail for these and for the top 4 above the velocity stacks an old cossy one fits perfect

    mark

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    This is fantastic wish I had your skills

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Loving this!

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Thanks chaps.....

    knocked up some adapters so i can use the injectors from the bike throttle bodys in the pinto injection rail




    i need to modify the injector rail to fit the bike throttle bodys ...but before i can do that i need to fit the bodys to the head..
    this is the idea of the tube inserts and the throttle bodies sit on top

    so test built the down draft tubes in the head using bolts instead of studs for now and drilled and fitted the top hats



    the throttle bodies need to attache to the top hats somehow..


    you can see there is not much room...so designed a fixing/sealing/positioning bkt..to suit the part in green


    got some 30 x 10 ally cut them to 95mm long and screwed them together to make a block 60 x 95mm x 10mm thk

    then made a jig and turned them on the lathe

    you can see i cut a groove for an o ring in the centre


    o ring and clamp plate separated ready to fit on throttle body


    o ring on body before clamp fitted


    allen bolts secured ...this clamping bkt is only the first fixing its main task is to keep the body aligned with the down draft tube..there is a second fixing that will apply the downward clamping pressure...(yet to make)


    so make 3 more and position all 4 on the head ..now i can modify the pinto injection rail to fit


    done ..painted it orange to make it go faster..and stop it rusting...
    mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    I now have a 500mm surface grinder..(now converted to 240v) so time to use it..

    The inlet surface of the head needs to be flat to get a good seal on the clamp plate gasket.
    .

    but after boring the holes for the inlet tubes the casting recesses are only 1mm away from the bores


    so cut some steel plate 6mm thick to the shapes of the recesses..jb welded and screwed them in position keeping them proud by a mm or so and ground the surface flat on my new toy..


    coated in oil to stop it rusting..

    to clamp everything in place i needed to drill and tap 18 off m8 holes each hole has to be in a part of the head where it doesnt break through any water way /oil way ect
    and of course 8 off at 61.5' to match the inlet tube angle..


    all of the fixings will be 10.9 studs (which i havnt sourced yet) so temp bolts for mock up purpose..

    to stop the inlet tubes rusting i blued them(heat to red hot and quench in oil)


    next i need to profile the ally plates to clear the rocker cover ect..i will convert the surface grinder for this.
    #
    mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Great work! Keep us updated

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    i decided to form the profile on the ally plates on my surface grinder...i cant grind ally so i decided to sand the profiles,,first i got a 4" rust removal disc and i ground the profile i wanted using my bench grinder and hand grinder.



    then when i had the shape i wanted i mounted it on my surface grinder and sanded the profile...




    finished profile trial fitted


    and misses the rocker cover..

    next needed to stop the top hats rusting so decided to blue them
    heat up to clear hot(after the color range but before red)


    then plunge in a bucket of engine oil.you can see it boiling if you look close

    then the blown engine burnt oil smell..



    all four done( do it out side)


    more bits to make...throttle spacing parts...ect

    cheers mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    I've just been reading in April's RetroFord magazine that they're building a big capacity Pinto race engine in conjunction with Dave Walker. It appears that they'll be trying 2 different cylinder heads - a conventionally ported injection head, and a machined and welded downdraught head.

    Hmmmmm....I wonder if a certain Guru on here knows more about this than he's letting on.


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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    interesting. ..i wonder...is this dave from emerald....keep us posted ...

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    couple of pics in the day light to see the colors of the top hats and down draft tubes..


    mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Quote Originally Posted by MemphisTwin View Post
    I've just been reading in April's RetroFord magazine that they're building a big capacity Pinto race engine in conjunction with Dave Walker. It appears that they'll be trying 2 different cylinder heads - a conventionally ported injection head, and a machined and welded downdraught head.

    Hmmmmm....I wonder if a certain Guru on here knows more about this than he's letting on.

    lol! dave doesnt have anything to do with engine buiding any more, but he has a soft spot for pintos and such like, so im not suprised if he is.

    but i dont actually know anything about this, i might have to pop in and see dave for a then i will know

    its not related to my big cc project though, once ive done a bit more work on it, and the business is properly functioning i will go a bit more public about what im upto.

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Just a quick question - why are you making the plate / tubes / TB attachment so bloody complicated? The tubes into the head I get - could have been ali or steel - a step and an o-ring seal at the bottom works, so why not just weld the tubes into a flat steel or alloy plate (either flush faced or with projecting tubes) that is then bolted to the head - traditional manifold style?
    The TB mountings ! ! ! - bike manufacturers come up with multiple ways to fix TB's to cylinders - most are either a slip sleeve or individual rubber 'manifolds' bolted to the head. They are simple and elegant, yours.................................is engineered for engineering sake and it ain't elegant.
    I admire your vision and drive but a bit of 'KISS' wouldn't go amiss.

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Katana ....yea..tried that first as its the simple way...but it wouldnt hold pressure..if i had a cnc mill where i could control depth and cutting sizes to 0.05 then thats the way to go...but as i said earlier its designed around the machines that i have....so the seperate top hats are my tolerance. after clamping all the inlet tubes in place with the required crush i can then check that all 4 are dead flat/in line any variation in height can be adjusted by skimming the required top hat..... i could have used rubber sleeves but because i need a solid foundation for the ecu controlled variable velocity stacks i need an adjustable fixing that will expand and contract to keep the seal and remain solid...and theirs tons more engineering..
    but believe me you couldnt get more simple than this design...

    and remember i'm an engineer not an artist..
    keep watching... it might grow on you...

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Quote Originally Posted by madragon199 View Post
    keep watching... it might grow on you...
    it has on me mate

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Never dis ingenuity, there are Many different ways to do anything, thank god or it would be a pretty boring way to live, theory is one thing getting the job is another, we would all have different solutions to projects like this with whatever tools we have, hats off to Mark for getting the job done!
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Very interesting and some great work. Ill be watching from now on

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Thanks guys..
    well all trial built and all is good..now ready for the variable velocity stack build then dismantle clean/polish paint ect






    Earlier in the thead i worked out my total inlet length including velocity stacks ..i noticed that there is a patern for best pulse tuning so i plotted it on the spread sheet (the red line)


    so all i need to do is to make my velocity stacks variable between the largest and smallest lengths...

    i wanted some way to control when they move ...i am using an emerald ecu to control the engine and the 8 injectors.



    so looked on the wiring diagram and noticed pins 10 and 17 are custom switched earths..



    A quick call to dave at emerald and yes we can use the p.w.m (revs:throttle position to control the switch) all i have to do is design and build a driver board (basicly on /off)

    so now i need to design the variable velocity stack ..i looked at the bike variations and the production variations but non really worked then i was reading engine technology and came across this..which ticked all my boxs



    so thats what i am making ...of course the other problem is it has to fit in the engine compartment..so i measured the space available and designed it to almost fit...to fit everything in i will have to move the engine 15 degrees and lower it 20mm and raise the bonnet 80mm....this keeps me within the rules if i ever finish and race it....

    cheers mark
    Last edited by madragon199; 12-03-2014 at 01:16.

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Quote Originally Posted by alladdin View Post
    it has on me mate
    And me,

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    variable velocity stack ......

    This build just keeps getting better.

    Shaun

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    Fantastic stuff

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Here is an example of variable length trumpets on a Mental Pinto, his engines had Everything bar roller rockers and 8 injectors, 15.89mm valve lift and light spring pressures using ti valves, unreal performance nothing like a regular pinto imho

    http://www.jpmotorsport.se/s/reporta...t_bilsport.pdf
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Cool..i remember seeing this but couldnt find it when i looked...be nice if mine runs half as good.. inspires us to try...

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    The basic velocity stack design..will be made in three parts (1) lower tapered stack fixed to the throttle body...(2).upper sliding stack..and(3) bell mouth end''


    As jason has pointed out the bellmouth only needs to have a radius on the end ..this is the most efficient ans simpliest to form as in pic (11)



    But when using the extra injectors it causes standoff because the pulses exit then return..for extra injectors the more complicated eliptical bellmouth works because the pulses end at the bell mouth (someone elses resurch pic)


    so before i do any thing else i will see if can make the required bellmouth...if you look at the picture (11) underneath is a eliptical bellmouth with maths..
    if i actually use these equations my bell mouths will end up at 120mm diameter...my ideal diameter would be 90mm so i am aiming to make something very similar to the eliptical but a bit smaller...

    i will spin a couple and post results tonight.......
    mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Good Stuff, yes in the trumpet diagram I would choose 8 ideally with a parallel or small taper and full roll back lip, that kind of shape creates the strongest pulse signal, but as you rightly said a flared entry with rolled back lip is best in terms of dampening fuel stand off

    That pic looks to be from an article the late Gordon P. Blair had written

    Here we go: http://www.nsxprime.com/w/images/9/9...Sept._2006.pdf

    Shape 11 looks like it could work as a good compromise between shape 3 and 10 (with a full rolled back lip)

    The longer the radius length along the trumpet the slower the change in CSA and the weaker the pulse signal, but I wonder how shape 11 would react to reverse flow with its much faster change in CSA than a long elliptical profile

    According to Blair the the trumpet radius also had the effect of lengthening the inlet length by the same amount as the radius, so a 300mm inlet length from valve to end of trumpet with an 8mm radius flare will act like the inlet length is 308mm, or if a larger 15mm flare was used that would be 315mm total length if you get my drift

    I think an inlet around the 400mm mark inc trumpet flare would be a good starting point (if there was enough space for such a length) for 7500rpm max power, or 300mm tuning for the next harmonic and space limitations

    And after reading this below I think dyno testing is really the only way to find the best length, which looks to be quite long

    http://www.emeraldm3d.com/articles/e...length-intake/
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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  33. #71
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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    yes thats where it comes from..i will have to go 300 ish because of space..and i have spoken to dave at emerald and he is happy to map and tune when its done....fingers crossed..

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    ok... having a go at spinning the bell mouths on my lathe..started with some inter cooler pipe 54mm i/d by 1.6mmthk


    cut a metal former out of some 5mm steel plate ..chucked up the tube...turned on the gas torch heated and spun the ally..

    well it didnt explode or fly out and hit me on the head...but i did manage to make it a triangle shape




    so if any one needs triangler bell mouths i can make them???

    ok had another go ..this time used a support ring on the outside...heat and spin....



    much better managed to get the outside diameter to 87mm and the inside to stay at 54mm
    its not the correct shape but now i no it works i can cut the profile i actually need and do 4 more...

    Mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Nice job, are you going to profile a piece of steel to the same shape you need and then cut a hacksaw line through it so that it can clamp the alloy pipe and form it to the required shape and using heat + a forming tool on the other side?

    Post some pics if you get time, spinning alloy is interesting, haven't done this yet but could be useful sometime
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Just noticed this video about making velocity stacks on a manual lathe, you have probably seen this already but impressive results!




    Better look at the form tool and finished velocity stacks here with full rolled back lip:

    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Hi jason..yes thats the video i copied..but i wouldnt wear gloves...mine didnt go as smoothly as his...my lathe is a belt drive conversion and the pressure required stalled my lathe if not really carefull..i found that i needed to half form the radius first then start forming the bell mouth shape...i actually ran out of material..i chucked mine on the inside and put a ring on the outside of the tube...i started with 58mm long tube and when finished i was at 28mm overall length and just about hitting the chuck jaws...but it does work and the chuck gets very hot as well...i hadnt seen the second video thats very helpfull..i found the form tool needs to be super smooth and fully radius...it did pick up but a quick sand and carry on...i couldnt take a pic as i need both hands ..ill set up a time delay next time im spinning...cheers mark
    i

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    Racer Decade Plus User RWD fords rule's Avatar

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Yes for sure gloves + machinery = very bad idea, I think if he used a 10mm thick steel plate and profiled it to shape, adding a very gentle radius to there the material begins to rub the alloy it would create a nice lead into the tool form rather than scraping the material, but also leaving the contact area fairly small to reduce friction

    Yes a 2 step process with 2 different tools would seem easier, also I think it would be easier to form a 1.3mm to 1.6mm wall rather than a light 1mm wall
    "Horsepower sells cars, torque wins races" - Enzo Ferrari

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    I even think you could fast form with straight taper then finish shape with the eliptical profile..

    yes 2 step is easier if you are only making 4..i reckon if you were making lots then a dedicated tool would be the way to go

    The other problem is.. you can not see when the ally is hot enough..i just kept the heat on all the time..i didnt use any lube.....when it starts to form just keep going its a bit like when inserting a tube..if you stop its a hard job to get it going again...when i do the real thing i will also put a lead in edge on the outer ring...mine was straight and the bell mouth formed a line not a blend..but this is all fine tuning..the principle works...and thats the main thing...

    I used 1.6mm wall intercooler pipe...its seamless and polished and about£10 a meter...great for the job
    mark

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Holy hell.That clip of the guy on the lathe gave me a flashback.........I was an 1st year apprentice and it was the dead of winter.I thought it would be a good idea to wear some pig skin gloves while I was polishing a shaft.Needles to say,the tips of the glove got wound up and pulled me off my feet.Next thing I remember Im laying on the ground wondering if I still have a hand.

    The artisan I was working under rushed over and inspected my hand.Two sprained fingers was his prognosis.

    Now the best part.........after deciding that I would survive and no major damage was done my artisan proceeded to slap me so hard that I was down on the ground again wondering if I still had a head.........Lets just say that after that slap I have never worn gloves,long sleeves,watch,wedding ring(much to my wifes dismay) or any loose fitting clothes to work again.Dead of winter you would find me with bare arms.

    Today 17 years later I can still remember that painfull slap....though I have trouble remembering the sprained fingers.

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    Pole Position Decade Plus User freddy686868's Avatar

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    Being a machinist myself i know the danger of these things unlike this idiot!

    I couldn't believe what i was watching when i first seen this. I'm sure his leg is broken too!
    http://www.youtube.com/watch?v=ajNdLT4exps

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    Re: Down draft b.v. Pinto with variable velocity stacks shed build adventure

    ive designed my version of variable stacks ....basicly it uses one driven power source up/down centrally placed driving 2 cams with a ratio of about 1.7:1..

    the basic design (1) lower stack fixed to throttle bodies (2) velocity stack clamp and bearing support/and cam follower support fixed firmly to the throttle body/head.

    The upper moving part (3) upper sliding stack..(4) bell mouth (5) upper air box base/injector fixing point/linear bearing fixing point..

    Fully extended



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    Got some ally tube 70mm o/d 10mm walls to start to make the top and bottom stacks cut on the chop/saw




    then turned for a good fit on the throttle body with a counter bore for the clamp/base plate


    Velocity stack clamp/bearing support plate ...cut and drilled with the 6 off linear bearing shafts fitted..



    Lower stacks placed in clamp plate before fitting to throttle bodys



    then fitted to the head/bodys..




    Next to make the clamp screws..i want to make them adjustable..then i can control the positions/parallel/height positions easier

    Mark

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