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ksmithgall

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About ksmithgall

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    New Member

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  • Map Location
    Longmont, CO

My Cars

  • Zcars Owned
    240z
  • About my Cars
    Just getting started with a project '73 240Z

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  1. Some good suggestions from everyone, thanks. I'll throw a lightened flywheel on the build list. For the time being, my plan is to sort out the head first and then tweak the bottom end as needed to support the head. Despite reading the saga of @madkaw's build thread I think I'll take on a MN 47 head. Seems like a great performance option for the L24 I have now (with bore notching for valve clearance), and would be easy to bolt onto an L28 block down the road for even more power. Let the search for a buildable core begin! A couple further questions based on @madkaw's build. Did you use the severe - duty Manley valves, P/N 11679-6, 11678-6, or something else? Any concerns about valve train wear from the increased seat pressure of the Isky valve springs? For the camshaft I could send my "Nissan" casting to Isky to regrind, but it's externally oiled. Which would be worse, externally oiled good metal, or newer internally oiled billet which may not wear as well?
  2. I recently picked up a non-running ’73 240Z with 160k miles that was sitting for years. The original engine has been pulled and disassembled and now I’m trying to come up with a rebuild plan for it. I know that the cheapest way to increase power is to buy and swap in an L28, but for right now I want to rebuild and get the original engine running with possibly some performance improvements. Generally I would want to reuse the original block, rods, and crank. Primary use would be street driving with an occasional autocross or track day. I have already acquired some round top SU’s and a ZX distributor with an E12-80 module that will be incorporated in the overhaul. Right now I’m considering two options. Option 1: Rebuild Like Stock ~8.8:1 CR Block: bore and hone 0.020” oversize, line hone main caps Pistons: ITM RY6335-020 From this thread I saw that the ’73 pistons were different: https://www.classiczcars.com/forums/topic/59242-interesting-1973-e88-240z-head-info/?tab=comments#comment-538427 I emailed ITM to check compression height, and they said the compression height of the RY6335 is 38.8mm matching the ’73 pistons that were originally in it so they should be an identical replacement. Rods: Hone and add ARP rod bolts, and re-use original L24 rods Crank: Polish and re-use L24 crankshaft Head: Rebuild ‘73 E88 head, replace bronze intake valve seats with hardened ones. New valves, valve springs, resurface original rocker arms Head gasket: Fel-Pro or equivalent Camshaft: ? The original “Japan” casting camshaft has a heavy wear pattern and would need to be re-ground. Would a more radical camshaft profile be a benefit given the rest of the build, or should the camshaft be re-ground/resurface to stock? Option 2: Maxima N47 Head ~9.5 CR Bottom end would be the same as Option 1, but notch block for larger valves or bore to 0.040”? Head gasket: 2mm HKS Head: find a Maxima N47 head, valve job, new springs, resurface original rocker arms Camshaft: Any recommendations for a camshaft that would suit this build and take advantage of a higher compression ratio? Is there an option 3 that should be considered? Overall has anyone gone put a Maxima N47 head on a Z L24, and what was it like, was it worth it? Thanks, Kurt
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