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Doing some stupid shit to an old datsun head

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  • TK
    replied
    Packed, will book freight in the morning.

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  • goracing
    replied
    How is my Head going?

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  • TK
    replied
    Just flowed it, needs a bit more of a rub

    Pretty much hit my flow targets, but I've got some turbulence/flow separation issues at high lift, above .600" lift the flow detatches from the short turn & it backs up 10cfm, I like a head to flow clean at least .100" past peak valve lift.
    I poked around a bit with a velocity probe, flow balls & a small steel ruler to work out where the issue is - looks like I need to blow out the bore side wall over the short turn a little, with the ruler I was able to get flow stable at .650" lift by pushing air across to the bore wall side & unloading the bore centre side - flow jumped up past 240cfm.
    Guides are in now & I don't have to pull them to rework that area so I should be able to nail it down pretty quick.

    Also have to 1/2 shaft the TB's - with the intake on flow dropped a solid 10-12cfm, not good enough.
    Throttle shafts are fairly thick, so I'm gonna pull em out & cut the screw head side off, then run the screws straight on the butterflys, that should be enough to get it where it need to be.

    On the exhaust side as suspected I fell a little short, not tragic tho & the flow is nice & stable, I'll leave it be - I'm having the cam ground with not-so-great exhaust ports in mind & I've got the cross section etc I need.
    Alcohol fuels blow down faster than petrol type fuels due to burning slower, so you don't actually need an 'ideal' exhaust port - handy when you're talking L series heads!

    If you're familiar with L series flow figures you'll note the low lift numbers are down over what you'd usually see - that's the chamber doing that, despite the cost to low lift flow it'll make more power - you can't always trust a flow bench, some things they'll tell you would lead you in exactly the wrong direction if you listen!

    Anyway, flow figures as it is now:

    Intake
    .1 - 58
    .2 - 104
    .3 - 147
    .4 - 180
    .5 - 217
    .55 - 229
    .6 - 235
    .65 - 226 - turbulent

    Exhaust
    .1 - 54
    .2 - 89
    .3 - 123
    .4 - 138
    .5 - 146
    .55 - 149
    .6 - 151
    .65 - 153
    .7 - 155
    .75 - 156
    .8 - 157

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  • Komdotkom
    replied
    Meh, no Les Collins no care

    I can't get over how round you get the ports by hand, fucking top work!

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  • Supashake
    replied
    Originally posted by Komdotkom View Post
    I want to do one of the six cylinder heads with the cast in liners and do a D shaped exhaust port with a raised floor, but I don't have any time for another project at this point.
    Edit: Looks like there's a four banger with the cast exhaust port liners too.
    I raced on one of these for 10 years, Mick Marriot did the head back then and the power was amazing. Early SR20s strugggled with it. 2.3ltr tho.

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  • Babalouie
    replied
    My god, that's sexual.

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  • DaveBxGT
    replied
    Epic, can't wait for dyno.

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  • TK
    replied
    Pics of finished porting, guides back in etc, just some quick ones while it's clean:



















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  • 2rismo
    replied
    Originally posted by TK View Post
    Just milled it down .040" & CC'd all the chambers, get this - all within .2cc!
    Arsey prick.

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  • Jim
    replied
    This is now on www.racemagazine.com.au and our Facebook Page too for a bit more exposure for you Tony.

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  • TK
    replied
    PS - that Peter guy should watch his back, he doesn't exactly have a clear conscience in regards to stealing ideas.....

    Mark will be in here some time soon.

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  • TK
    replied
    Meh, everything has been done before.

    Just milled it down .040" & CC'd all the chambers, get this - all within .2cc!
    I would have been happy with within .5cc & was almost expecting to have to tweak a little.

    Can't mill it to finished thickness until I get the proper valves, but looks like another .030-.035" needs to come off.

    Gotta make a bore adaptor for an 86.5mm bore to flow test & find my Datsun valve lifting jig, so figures will be late this arvo.

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  • clutch-monkey
    replied
    Lol just read the Datsun fb page this morning, fuck the Datsun community is a toxic shit pile

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  • tim510
    replied
    stupid internet argument. carry on.

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  • FEAR
    replied
    O someone link the race magazine write up and the Peter MC guy say it's old work done by others years ago.

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