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1G 4gcs with 4g63T head

Posted by ndillon347, May 6, 2019

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  1. ndillon347

    ndillon347 Probationary Member

    Joined Apr 1, 2018
    Lewistown, Pennsylvania
    Alright, so I have an opportunity to pick up a high mileage 4gcs from a local junk yard for cheap. The plan would be to turn it into a 2.2L long rod destroker. I currently have a built 2.0L 6 bolt that I could easily yank the crank and timing components off of, but the question becomes what to do with my built head? Will the 6 bolt 4g63T head drop right onto the 4gcs where the SOHC head used to be? Is there any modifying of oil passages that needs to be done? Also the 4gcs will be bored out to 87mm (.02 over) to rid the cylinder bores of any scars it may have left. So that also leads me to ask will the combustion chamber on the 4g63T cause any issues since it is desigend for a much smaller bore?

    I do understand that this is the "6 bolt version" of a 4G64 so it will easily drop right into my 1G, but just to be safe has anyone bolted up a 6 bolt AWD trans to this block with success? The engine is coming out of a 1990 Galant with VIN code S and this has been verified by the junk yard. Any help on this would be great considering I am going to potentially pick this engine up very soon.
  2. jery1234

    jery1234 Proven Member

    Joined Jul 26, 2008
    Toronto, ON, Canada
    Everything fits with no problem head included, all you have to choose is compression ratio of the pistons

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  3. ndillon347

    ndillon347 Probationary Member

    Joined Apr 1, 2018
    Lewistown, Pennsylvania
    Now with the combustion chamber being different and the bore being larger, advertised CR of the piston wont be exactly what is achieved correct? To the best of my knowledge it is dependent on the dish?
  4. ThunderChild

    ThunderChild Supporting VIP

    Joined Jan 5, 2012
    Rathdrum, Idaho
    Not quite accurate. There are a couple oil drain back holes you have to block off, laying a 4g63 gasket over the g4cs deck will show you which ones need to be blocked. Freeze/core plugs have been used to block them in the past, as well as a couple other methods, it's your choice. Otherwise the head bolts up no problem.

    To calculate compression you will have to take into account total swept volume (bore-stroke), combustion chamber volume, piston dish and HG thickness.
    Doing a 2.2 destroker isn't going to change your compression much from a standard 2.0, but as long as you know the dish and compression height of the pistons, as well as the other figures I mentioned, you can calculate compression relatively easy. There are also several online calculators that do the hard work for you as long as you know the necessary values.
    Last edited: May 6, 2019

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  5. ndillon347

    ndillon347 Probationary Member

    Joined Apr 1, 2018
    Lewistown, Pennsylvania
    I have checked out the online claculators but when it comes to combustion volume, I have no idea on my head. I have never done the water volume test, but I did not change my valve size or anything. I have also seen the freeze plug method and the "drill, tap and plug" method but I wasnt sure if those exposed holes were on the 6 bolt 4gcs. I would use a 1.2mm HG.

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