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Thread: Cylinder head rebuild

  1. 02-26-2015, 01:50 AM #1
    Will 1967
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    Cylinder head rebuild

    I'm in process to get cylinder heads rebuild, what is current consensus what parts should be replaced for proper job and what can be re-used if condition permits? (I have to order parts for machine shop)

    - guides and stem seals will be replaced anyway (when rebuilding, can std size quides be used or do they need to be oversize?)
    - intake valves ok to re-use (if straight and enough material left)?
    - Exhaust valves should be replaced?
    - how about valve springs, re-use or replace?

    Other suggestions what to replace/re-use?

    This will be for stock 2.0 (130hp) alu engine.

    Many thanks!
    - Ville -

    1967 911 Slate Grey/red, fully restored + 66' "r-ish" hotrod project
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  2. 02-26-2015, 02:00 AM #2
    preS
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    If the valves are w/i spec (check your little spec book for the specifications) and they have no defects (burned, or not straight) you can use them. Most of the used valves however are out of spec since the tolerance is minimal.

    The springs you usually can re use unless they have visible stress risers like pitting / corrosion.

    Richard
    searching for engine (case) 903742
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  3. 02-26-2015, 03:28 AM #3
    edmayo
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    Valve guide replacement is where most heads are screwed up. The old guides must be core drilled with a special stepped drill then driven out. Core drilling relaxes the guide diameter so it doesn't enlarge the head as it is removed. Once the guide is out you need to measure the I.D. of the hole in the head with a ball gauge to determine the exact dimension. Then referring to the spec book you can compare I.D. and O.D. of the guide to get the required interference fit. The correct fit will involve heating the head and freezing the guide to install, then when the head normalizes the guide will be 'locked' in place.
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  4. 02-26-2015, 10:31 PM #4
    Will 1967
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    Thanks! Machine shop I'll use is familiar with 911 heads so they should be fine changing guides.

    Shame that 2.0 valves are so expensive vs other variants.
    - Ville -

    1967 911 Slate Grey/red, fully restored + 66' "r-ish" hotrod project
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  5. 02-27-2015, 08:47 AM #5
    304065
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    http://forums.pelicanparts.com/911-e...ese-heads.html
    1966 911 #304065 Irischgruen
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  6. 02-27-2015, 09:42 AM #6
    Harvey Weidman
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    Quote Originally Posted by Will 1967 View Post
    Thanks! Machine shop I'll use is familiar with 911 heads so they should be fine changing guides.

    Shame that 2.0 valves are so expensive vs other variants.
    If you are using a machine shop that does 911 heads, then you should trust him with the decisions about what needs replacing....
    I wouldn't second guess a experienced machinist...
    H
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  7. 02-27-2015, 10:41 AM #7
    NeunElf
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    Quote Originally Posted by Harvey Weidman View Post
    If you are using a machine shop that does 911 heads, then you should trust him with the decisions about what needs replacing....
    I wouldn't second guess a experienced machinist...
    H
    That's what I did (356 & 911). The engines haven't exploded since.
    Jim Alton
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  8. 02-27-2015, 10:50 AM #8
    37yrold911
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    RSR seals?
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  9. 02-27-2015, 11:52 AM #9
    edmayo
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    Doesn't hurt,,,,they do help (I'm assuming you mean the rocker shaft seals)
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  10. 02-27-2015, 12:05 PM #10
    37yrold911
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    yes, the RSR style rocker shaft seals as per the late, great Bruce Anderson (or Jerry)
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