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Author Topic: which cylinder head is better?  (Read 1428 times)

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Offline bucky katt

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which cylinder head is better?
« on: March 11, 2010, 12:50:57 PM »
i have the original head off of the k6 750 motor and i also have 2 heads from cb750f's a 1975 and a 1976. which one am i better off starting a port job with? i'll be replacing guides as well, and valves if theyre worn too much. this is a mostly stock motor with a 3rd overbore (755cc's) i'm going to have around .020 milled off the deck surface in addition to cleaning up the ports and ccing the chambers. i'll be running a 1977 cb750f cam with points and a hondaman ignition (man i love being able to type that...hondaman ignition  ;D ) and a kerker pipe at the moment, going to either a cyclex 4-2-1 or a carpy pipe (probably the cyclex pipe)
« Last Edit: March 11, 2010, 02:23:39 PM by bucky katt »
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Offline Old Scrambler

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Re: which cylinder head is better?
« Reply #1 on: March 11, 2010, 01:22:20 PM »
I am not aware of any changes to those years..........check the rockers/shafts and reload as a complete unit in correct order.
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Offline bucky katt

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Re: which cylinder head is better?
« Reply #2 on: March 11, 2010, 02:20:12 PM »
i was thinking that maybe the f head might have better ports, i need to decide which one i'm going to re-work
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Of all God's creatures there is only one that cannot be made the slave of the lash. That one is the cat. If man could be crossed with the cat it would improve man, but it would deteriorate the cat.
Mark Twain - Notebook, 1894

Offline eurban

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Re: which cylinder head is better?
« Reply #3 on: March 11, 2010, 04:14:37 PM »
76K and F heads are different.  The pre 77Fs and the 77/78ks have a redesigned head with a more "hemi" shaped combustion chamber.  They should flow better stock than your 76K head although there can be a bit of range in the quality of the factory work on any given head.  Most likely the pre 77f heads will be your best bet . . .
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Offline bucky katt

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Re: which cylinder head is better?
« Reply #4 on: March 11, 2010, 04:31:09 PM »
excellent, i'll start tearing the f head down tomorrow, checking clearance between valve and guide, see what kind of condition the seats are in. if i'm lucky i wont have to do guides or valves then all i'd need to do on that end of things is polish the valves right under the head. i have a large cache of carbide cutters and sanding flap wheels for the 1/4" air die grinder, my cc kit from when i built air cooled vw heads and then the putty to check valve clearances after i get the head milled with the 77f cam.
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Of all God's creatures there is only one that cannot be made the slave of the lash. That one is the cat. If man could be crossed with the cat it would improve man, but it would deteriorate the cat.
Mark Twain - Notebook, 1894
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