Chevy 350

Discussion in 'Inboards' started by mikealston2428, Aug 3, 2016.

  1. mikealston2428
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    mikealston2428 Senior Member

    Not sure about this ?
     

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  2. mikealston2428
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    mikealston2428 Senior Member

    Lastly
     

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  3. PAR
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    PAR Yacht Designer/Builder

    The daisy wheel looking thing is when the head was cast (about 6:00). The key to these numbers is really the last few digits and the 441 casting is a pretty standard early smog head (1970 is my guess, but the date code isn't visible in the casting number photo). It has 74 cc chambers, 160 cc runners and 1.94"/1.50" valves. This head can "wake up" with some machine work, removing the "smog humps", a light decking and relieving the valve bosses a little. Simply put, they'll do fine on your engine, as they have a thick deck. They were put on a 1969 or '70 Chevy 350 originally. The chamber size suggest a low compression application (9.5:1 probably).
     
  4. mikealston2428
    Joined: Jul 2011
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    mikealston2428 Senior Member

    Thank you Par very helpful as always !
    As for the correct E3 spark plugs what would you recommend?

    I'm running a marine DUI HEI distributor.
    The specification for gap can be as much as .55 for this distributor.
    Is there any advantage or disadvantage off. 55 for my engine ?

    Simply put what's my best plug and gap for marine engine

    Thanks again
    Mike
     
  5. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    E-3 plugs are a fixed gap design. You pull them from the box, spin them in and install the boots, that's it. In other words, you're married to the gap they give you. Your engine takes an "E3.42" which is a 5/8" plug, 14mm thread and a tapered seat. It's all about "reach" with these plugs, for a first gen 350. Does your head use a 5/8" plug socket? If so, use the E3.42's.
     
  6. mikealston2428
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    mikealston2428 Senior Member

    Hi Par

    These are the current plugs
    Would you be able to tell me the E3 equivalent?

    I see the E3.42 have a 44 reach
    I'm not sure what the AP85 is ?

    Im unsure if the current plugs are even correct for my engine ?

    They have seat gasket and 13/16 socket

    Should I be using tapered seat ?

    Thanks
    Mike
     

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  7. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    The replacement for the AP-85 is the E3.52. This is a 13/16 socket, 14mm thread, 3/8" reach, with a gasketed seat. The question is, was the right plug installed in this engine, as both the E3.42 and E3.52 have the same thread, though the 52 has slightly more reach. The quick check is to look at the seat in the head. If it's tapered, the Autolite plug is incorrect, if it's a flat landing area, you'll need a gasketed plug, like the E3.52.
     
  8. mikealston2428
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    mikealston2428 Senior Member

    Hi Par

    Almost there

    Had a look and the seat is flat so it is the 14mm gasket plug

    The3/8 reach of the E3.52 is this correct for my engine ?

    Thanks
    Mike
     
  9. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    What's the date code on the head (just below the casting number)? If it's a 1969-70 350 head, it'll run ever so slightly better with the extended reach of the E3.52. If this is the head I think, the plug will be all but flush with the chamber when installed, which is ideal.
     

  10. mikealston2428
    Joined: Jul 2011
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    mikealston2428 Senior Member

    Hi Par,
    Yeap after you're advice and a bit of research the E3.52 are correct one's for my engine and I've ordered them

    I'd like to thank yourself in particular and many others on this site for all the invaluable information and knowledge given to all of my posts since the very start of my engine rebuild.
    Basically I couldn't have done it without the help of all the knowledgeable members of this site ! !
    Many Thanks Team.
    Mike
     
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