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  1. #1
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    Default Basic/DIY VN head porting

    Doing these for a local & I told V8bulldogs I'd pop some pics up so he's got a bit of a guide to hack his turbo 383 heads up a bit.

    This is real simple KISS porting - max improvement for min time spent.
    There is only $300 worth of porting here, but the gains are substantial.

    Before the inevitable question is asked - yes I do heads like these for low buck customers all the time, a typical combo is stock stroke 304, stock rods & flat tops, 11:1 comp, 288 crane, bolt on YT's off ebay/gumtree & either a harrop or TP single - whichever pops up 1st on ebay/gumtree.
    They make 400-430hp on pump 98 & scoot along quite nice in an early commo.
    They get:

    Hot tank
    Bead blast
    Good valve job (Radius/20/35/45/65/75 intake seat, Radius/20/35/45/Radius exhaust seat)
    Refaced stock valves
    Spring seats cut for double springs
    Guide tops cut for positive seals
    Porting
    Milling to whatever chamber volume required
    Valve tip heights set
    Good wash

    Done as bare heads with stock valves unassembled they cost $1250

    Assembled with crane springs, retainers, locks & seals to suit a SFT cam they cost $1800

    Now that's out the way, on with the pics, the cutters I use are large & agressive, for a DIY guy stick to double cut burrs & smaller diameters - easier to control.

    Intake guide boss, run the cutter down either side right to the roof & round off the leading edge of the guide boss, straight sided round nose cutter:





    tidy up the bowl & blend in the valve job, flame cutter:







    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  2. #2
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    Default

    Now the short turn, this is the important bit, I've tried to capture the shape as best as I could with a 2D picture, flame cutter again:











    Runner entries, just knock down the lumps for the pushrod holes & even up the width from top to bottom, flame cutter again:









    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  3. #3
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    Exhaust guide bosses, oval cutter (yes it's a CHA fast cut & it's beat to shit, but still cuts like a demon):







    Smaller dia oval burr to do the corners & clean up the RAG finish from the chipped up fastcut:





    Smaller double cut flame burr to blend in the valve job:





    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  4. #4
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    Exhaust short turn, flame cutter again, just roll over sharp edge & blend n the valve job:









    Last job, knock the edges off the plug boss:



    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  5. #5
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    With this valve job & porting they flow the following, give or take a couple of cfm (haven't flowed these ones, but I've done quite a few head like this & they always flow the same), it's not pretty, but it works much better than it looks!:

    Intake:
    Lift - flow - hp potential
    .1 - 61
    .2 - 129.5
    .3 - 177 - 364hp
    .4 - 216 - 444
    .5 - 230 - 473
    .55 - 235 - 483
    .6 - 238.5 - 490
    .65 - 243 - 500
    .7 - 248 - 510
    .75 - 249 - 512

    Exhaust
    Lift - flow
    .1 - 49
    .2 - 100.5
    .3 - 135.5
    .4 - 152
    .5 - 160
    .55 - 162
    .6 - 163.5
    .65 - 164.5
    .7 - 165.5
    .75 - 166.5
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  6. #6
    Do you ever leave? v8bulldogs's Avatar
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    Perfect mate.

    That's exactly what I was after, Thanks very much for sharing this.

    I usually like looking at the .50 lift figures that you post as that's around the lift I'm running. These pictures showing the cutting done and the flow for these heads gives more of an idea on how much skill and cutting it would take to get the figures up around the 280-290 cfm that you posted in the vn head thread.

    Just a question about the pushrod lump in the inlet port just inside the window or whatever it's called, does it get cut back to flush with the wall so no pushrod lump is left? I tried eyeballing it and it must go real close to cutting into the pushrod hole if it is cut back to flat.

    Thanks again TK.

  7. #7
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    I will most likely get a set of valve guides done kline or something. does that mean the intake valve boss can be chopped a little lower ? if so how much of the boss can get chopped off before fitting the guides?

  8. #8
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    Yep, knock the pushrod lump in the straight wall to flush, you won't go through, on the other side just round the lump over & clean it up.

    If your guides are ok then just leave them, I don't cut down the height of the guide boss unless I'm getting real serious, bugger all flow to be had & reduces support for the valve stem.

    PS - get the heads looking close to this & stuff in that cam we talked about & you'll be up at least 100hp on the same boost.
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  9. #9
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    tk- whats an untouched vn port flow on your bench?

  10. #10
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    Anywhere from 210-220cfm, haven't flowed a stocker for years tho, I had a sheet from a set but lost it, maybe Pete's got a sheet from a stock set?
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  11. #11
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    These are going on a stock stroke 304 with flat tops & zero deck, 288 crane, 12:1 comp, harrop & QF750 E85 carb - should be a fun motor.
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  12. #12
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    Quote Originally Posted by v8bulldogs View Post
    I usually like looking at the .50 lift figures that you post as that's around the lift I'm running.
    If you are running a flat tappet cam with only .500" lift dont look at the .500" figures on a flow chart the cam spends limited amount of time there, look at .400 thats where you will be most of the time.

  13. #13
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    Quote Originally Posted by TK383 View Post
    Anywhere from 210-220cfm, haven't flowed a stocker for years tho, I had a sheet from a set but lost it, maybe Pete's got a sheet from a stock set?
    i got a flow data for a stock set of VT heads but its on the flow bench pc at the workshop ( around 220cfm ), day off today yeaha.......good job of showing the basic VN porting tony, tk's covered it all here not much else you could say really but yes this is the best bang for buck and will give the biggest cfm per dollar gains over all other porting levels, as the porting levels go up each cfm gained takes more work, this port job with a 2.02 would flow around 540hp

    eg getting 550-560hp flow ( 267-272cfm ) is easy with a 2.02 but beyond that a little fine tuning is involved and thats where a flow bench is of good use unless you already have had flow testing experience with these heads.

    i think the ex port stock flows around 145-150cfm but im really guessing now, like tk said flowing a stock set is really of no use to us but the last stock set i flowed was around 4 years ago when we got the new flow bench software
    Last edited by HPE PETE; 27-07-2013 at 03:50 PM.

  14. #14
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    A day off! - lucky bastard.

    I'm millng .090" off the heads in the pics ATM, mill is making horrid noises with .010" cuts at high feed.
    I'm not on here much any more - don't bother PM'ing me, chances are I won't read it, just call me on 08 8376 9540 if you need to get hold of me or email knight28@optusnet.com.au, phone is better!

  15. #15
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    I guess you would do much the same for early heads?

    Will send you an email shortly TK

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