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  1. #1
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    Default Help wanted building a decent 308 for my LX SLR copy

    Hi folks
    I am reconining 76 red 308 for my LX.
    It currently has a 253 so rather than throw money to get some more hp I figured 308 cheaper HP.

    Couple of questions- the bore looks ok and is 20 thou over.
    The pistons are unmarked brand wise and have valve recess in them. They are flat tops in good nick. They Measure 101.65 mm which is 4.001 inch from conversion table. They are flat top. Top ring gap is about 25 thou. Others say aim for 18 thou top 20 second?

    The rods just say Holden. Top ring clearance to block top is .0100 though. 2.45mm.

    I am pretty new to V8 builds but it sounds as though the block would benefit from being skimmed or decked? Does this mean I get new pistons and have machinist skim to 0 clearance.

    The heads are pre early reds with l34 spec valves.
    I plan to put a crane 276 cam in it and fit a edelbrock performer intake. It can with 1/2 inch riser and newish 600 cfm eldelbrock carb. It has roller rockers. Some say replace standards with 5/16 walled versions. Do I need to? Will standard hydro lifters suffice?

    Main thing is I want a really nice streetable motor with the best hp I can get cheaper the better. Still got to spend 5 k on total trim kit.

    Hope some of you can answer some of these questions so I can get onto it. I have the skills to work on myself.

    Any advice would be great. U folk have provided some great advice info so far. New to Toranas too.

    Regards
    Richard

    I meant top piston clearance to block top is 0.0100 thou not from ring.

  2. #2
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    before you buy cam and intake get vn heads wont cost anything for a lot better head

  3. #3
    Do you ever leave? paulzig's Avatar
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    Quote Originally Posted by Screamin View Post

    I meant top piston clearance to block top is 0.0100 thou not from ring.
    Thats f-cked, WAY too much you will have very low compression.. Someone has put some weird pistons in there, Holden ones are either true flat tops or dish, no eyebrows, thats usually for Chevy pistons... You cant deck .100 off the block, there has been a stuff up somewhere, you'll need new pistons...

    If you want the true SLR look in the engine bay, you'll have to keep the early heads, if you dont care VNs .. They do look a bit odd if you want a replica though..

  4. #4
    been here .......too long Smitty2's Avatar
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    Quote Originally Posted by hq2door View Post
    before you buy cam and intake get vn heads wont cost anything for a lot better head
    a different zorst' also is needed with VNs
    plus really not the look for a V8 Torrie
    if you are trying to keep the thing 'standard
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  5. #5
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    Hi
    cubes 355 option ,about the most you can suck thru straw sized factory cylinder heads
    = scat crank ,rods and speed pro pistons
    = hp gain and stock appearance
    eg run stock exhaust manifolds saves money !! although costs Hpower


    TOP END STUFF --all canbe done later
    Factory stuff/// heads either factory red with factory inlet manifold ,Rochester carby
    OR
    vn commo heads extractors to suit plus after market holley carb and edelbrock manifold

  6. #6
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by paulzig View Post
    Thats f-cked, WAY too much you will have very low compression.. Someone has put some weird pistons in there, Holden ones are either true flat tops or dish, no eyebrows, thats usually for Chevy pistons... You cant deck .100 off the block, there has been a stuff up somewhere, you'll need new pistons...

    If you want the true SLR look in the engine bay, you'll have to keep the early heads, if you dont care VNs .. They do look a bit odd if you want a replica though..
    I think itís just the way itís written but I read it as 10 thou (the op wrote .0100Ē)

  7. #7
    Do you ever leave? paulzig's Avatar
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    Quote Originally Posted by hq308 View Post
    I think it’s just the way it’s written but I read it as 10 thou (the op wrote .0100”)
    Yeah but it says 2.54 mm after it so I took it to mean the .0100" should have read .100", because if it was 10 thou you'd just go .010

  8. #8
    Not the Kingswood! hq308's Avatar
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    Quote Originally Posted by paulzig View Post
    Yeah but it says 2.54 mm after it so I took it to mean the .0100" should have read .100", because if it was 10 thou you'd just go .010
    I missed the 2.45mm, I agree .100Ē is too much.

  9. #9
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    Thanks gents. Have done a few measurements. Straight edge with feelers and tail of verniers. Both come out around .114 thou or 2.86 mm. Like you say sounds like rods or pistons incorrect.
    Piston compression height is 41.75mm or 1.64 inch. Stroke is 77.8 mm or 3.06 inch. Rod length is 142.65 mm or 5.165 inch. Wrist pin standard 23.5 mm or 0.925 inch.

    Then I have that 2.85 mm piston top to deck height?. Am I right in assuming the piston compression height is too little. ACL sell standard 43mm compression height pistons. These look like chev replacements hence the valve recess. Iíll post some photos. Bear in mind Iím using pretty basic verniers etc but triple checked everything between digital and manual types.

    Thanks
    Richard

  10. #10
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    Thanks fellas for the advice. Since then I have taken some more measurements with cheaper digital and dial verniers and dial gauge.

    So in summary
    Rod length is approximately 51.56inch or 142.65 mm. ACL standard says 142.87. A9L says 144.78 mm or 5.7 inch.
    Compression height is 1.64 inch or 41.75 mm.
    ACL standard says 43mm
    Gudgeon 23.5 mm same as ACL.
    My deck gap to top of piston is 2.8mm give or take.
    My stroke is 77.8 mm or 3.06 inch.

    The main issue seems to be those possible chev style pistons having a compression height of 41.75 versus 43 of ACL standard. Thatís a 1.25mm gain straight up taking deck to 1.55mm.

    Mind you all my measurements were on basic verniers etc. Does this seem to gel?

    Looks as though ACL race rebuild kit may be the best option, rebore and deck.

    Iíll stick with the red heads and just have port job. Not sure if better valve springs added when rollers were put on. And it sounds as though I should upgrade rod bolts if I reuse?

    Thanks for any advice so far and to add.

    Have photos but no idea how to add on here.

    Cheers Richard

  11. #11
    Do you ever leave? paulzig's Avatar
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    yeah basic verniers accuracy is still enough, 1mm is too much you have over that you should be a max of .010 down the bore which is .254mm the closer to zero the better...

    Someone has put chevy pistons in there, maybe out of a 327 or something... They have to go, you cant deck that much off the block, I suggest buying true flat tops and making the compression around 10 to 1 ... Harder to get compression with a dished pistons

  12. #12
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    Thanks guys. Appreciate all the help. I think you right Paul with the chev piston problem. Iím going to post a quote I had put together for my 308 rebuild. Keen on peopleís thoughts regarding the prices.
    Cheers
    Richard

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