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Thread: Ford 460 Heads

  1. #21
    058
    Tim, The cast pistons have got to go! Get a set of TRW #L2404F pistons, they are cheap enough [$255.00-Summit] 19cc cup and with the A2A heads [92cc]should put the compresson at about 8.25 to 1. Get a set of truck/CJ rods & a set of ARP bolts, shot peen the rods and recondition. The cast crank should be good for about 6500+ rpm if you stud the mains, again ARP will work great. Have the block bored with a deck plate and have the block square decked and align honed. With all this done the short block should be good to about 6500 with the rods being the limiting factor here or you can step up and get a set of Eagle rods, about $700.00 for extra ins. I would limit boost to about 10lbs for safe operation and keep it from detonating, run good gas [racing mix] and read plugs. My engine is a 4 bolt block [steel splayed caps] Moldex crank, Crower steel rods and JE pistons with a 20cc reverse dome. A little overkill as I did run a stock short block/with the above forged pistons with no failures with exception to a few burnt pistons and lifted the heads a few times but no bearing failures, main cap walk or broken rods ect and I wasn't kind to it either.

  2. #22
    058
    Tim, almost forgot, If you had some piston exit the engine check the turbo impeller for damage. Any damage at all, [nicks, bent blades or chunks removed] and you will need to replace the impeller/shaft. If you don't the turbo will shake itself apart. Happen to me when I fryed a piston and some parts of the rings tried to get out thru the turbo, made a mess of things but caught it before the turbo was totally junk.

  3. #23
    Beavertim
    058,
    I did take off the exhaust manifold downstream of the turbine and there were no nicks or even scratches on the impeller (same as the Head and valves). I can't understand why someone (previous owner or ownwers mechanic)would go and replace the head and rebuild (or fix) the turbo and not replace the piston! or if that's not the case, how the piece(s) of piston and 1/2 a compression ring could go through the exhaust without even scratching the head/valves/turbine. I ended up doing a quick fix (so I can use the boat a little more before the season is over) of replacing the cast piston, cleaning out the exhaust ports and getting it back together. I plan on putting in forged pistons, larger cam, etc. this winter. Do you think my single 750 CFM Vac secondary Holley can feed enough fuel for 5500-6000 rpm @ 8psi boost? My calculations say thats over 900 cfm. The secondary jets are 90's, I don't know whats in the primaries. Looking forward to hearing from you, as always. Tim

  4. #24
    058
    Wow, How lucky can you get? No turbo damage, just a couple of junk pistons. Sounds to me someone just did the top end and didn't bother with the short block, maybe they ran out of money. When you had the A2A heads off did you notice if they are the open or closed chamber variaty? The 750 should work fine for you, but I prefer a mechanical secondary carb, more consistent and better control. I run an 850 center squirter and it seems to feed enough fuel for 7K+ rpms and 15 lbs of boost. Its jetted at 84 pri. 94 sec. no p/v in sec. I've never tried anything bigger as its plenty for me as is. A word [or few] of caution is to watch fuel pressure, you should have NO loss of F/P at any rpm/load. Even the loss of 1 lb can drop float level 1/8". A naturally asperated engine may tolerate such a lean out but under boost conditions things like detonation and pre-ignition happen alot quicker and do more damage. Let me know about the heads [chambers] it makes a difference.

  5. #25
    1riverrat
    Question for 058 did you do any thing to the oiling system to have your 460 to survive at 7000 rpm. Thanks in advance.

  6. #26
    Beavertim
    058,
    I'm not sure whether they're open or closed chamber. How can I tell? Tim

  7. #27
    058
    Oiling system: just a 10 qt pan/windage tray, CJ pump[bolt on p/u] The dual inlet helps too and not much else. Tim, the heads that are closed chamber have a portion of the combustion chamber machined surface of the head, called the quench area. Open chamber heads will be sand casted the full surface of the cylinder. The closed chamber are better for the turbo as the quench will provide turbulance when the piston reaches TDC providing the deck clearance is less than .040". When you rebuild this winter have the block square-decked and cut to provide a deck clearance of .010", check compresson ratio and lower via the combustion chamber voluume without disturbing this quench area. Your block is likely a 10.320" deck, have it cut to the common 10.300" [the same as early blocks] With the TRW pistons and the CJ/truck rod this should get you close but let the machine shop do the final math before they cut.

  8. #28
    058
    Some more on carbs....Is the power valve boost referenced? If it is there should be a vacuume line running from below the intercooler or at the manifold to the carb p/v vacuume chamber with the orig. passage going to the bottom of the carb blocked. This is important if you are running a pri. p/v. If this isn't done then its likely the p/v may never open or will close when you need it the most. The vacuume below the carb isn't the same and does not respond the same as engine manifold vacuume.

  9. #29
    Beavertim
    058,
    I wasn't positive, but thought thats what defined closed chambers (portion of the head surface in the combustion chamber). Mine are closed chamber.
    On the other subject, the metering block is vacuum/boost referenced off the manifold, but it is the secondary block thats referenced. There is a power valve in the secondaries, but I haven't taken off the primary bowl yet to see if there's a PV in there. If there is, does it also need to be refernced? Tim

  10. #30
    058
    Tim, I would recommend to block the secondary P/V and jet up accordly and to boost reference the primarys so the engine will not be over-jetted at part throttle-cruise operation. Also I opened the PVCR on the primary side to .078-.080" [don't remember, its been awhile since I've been into my carb] just to keep it a bit on the rich side and safe.

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