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Thread: How much does an E31 head weigh?

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    HLS30A 17574 djwarner's Avatar
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    Default How much does an E31 head weigh?

    I'm just about ready to pull my head to change a head gasket.

    How much does an E31 head, cam, and valves weigh?

    After a day bending over the fenders pulling manifolds, my back is complaining. Just trying to figure out what I'm in for tomorrow. Is it a two man lift?
    1971 240Z HLS30A 17574 L24-021025

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    Registered User madkaw's Avatar
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    Not really too bad. The hardest part is getting it broke loose to pull. One of my favorite tools is a 3lb dead blow hammer. Get her loose and use the cam as a handle to pull it off. Don't forget those 2 pesky bolts at the timing cover topside
    Steve
    71 240z,bw-5sp 2.4-40 over,balanced,e-88,big valves,ported&polished, stage2,header, triple Mikuni's 40's
    3.90 Subaru STI LSD

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    Registered User siteunseen's Avatar
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    I've figured out, after sleeping on the floor, to raise mine up with jack-stands a couple of feet. 6 ft. tall bent down to 3 ft. takes the fun out of working on mine.
    1972 240Z #918 New Sight Orange
    1977 280Z #305 Light Blue Metallic
    1972 240Z #110 Persimmons Red

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    Registered User Lazeum's Avatar
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    My P79 head complete with head cover was recorded at 70 lbs.

    You can do it on your own but make sure you protect very well the fender in case you have an issue during transfer. If you can have somebody helping you, it would be easier for sure but it is far from being impossible to do by yourself.
    Matt - 72' 240z

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    Registered User black gold man's Avatar
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    Look what can be found when you know were to look. http://www.cardomain.com/ride/296974...n-280z/page-3/

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    I removed my E31 head a couple months ago...while I had a hernia. It wasn't that bad but if you can get a friend to help it'll be much easier.

    Chuck
    East Coast Z Nationals held at the Carlisle Import & Kit Nationals - May 16-18, 2014 Carlisle, PA
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    1969 240Z #390
    1971 Fairlady Z
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    1972 240Z ITS race car
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    1975 280Z my first car
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    HLS30A 17574 djwarner's Avatar
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    Ok, Got the head off and on the bench. Noticed that the oil galley hole feeding the head appears to have an orifice jet about 2mm in diameter. I assume this is correct and not a piece of junk blocking the oil feed.

    With the three design variations in head gaskets and three different head bolt torque specs, Contacted FelPro for what the felt the specs were for their gasket. They came back with the factory spec.s of 33 ftlbs, followed by 47 ftlbs for my 12/70 car.

    Have others had satisfactory performance at this low torque spec?
    1971 240Z HLS30A 17574 L24-021025

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    Registered User cbuczesk's Avatar
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    I think they forgot the 3rd torque number. Off the top of my head I think the final torque is 60 or 70. Turbo bolts are 70 or 80. I can get exact numbers when I get home.

    Chuck
    East Coast Z Nationals held at the Carlisle Import & Kit Nationals - May 16-18, 2014 Carlisle, PA
    www.carlisleevents.com/events/import
    1969 240Z #390
    1971 Fairlady Z
    1971 240Z parts car
    1972 240Z ITS race car
    1972 240Z turbo
    1974 260Z turbo
    1975 280Z my first car
    1978 620 King Cab

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    Registered User siteunseen's Avatar
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    Tom Monroe says on page 129, L24, 26 and 28 final torque of 61 ft-lbs. That's a Fel-Pro gasket too.
    1972 240Z #918 New Sight Orange
    1977 280Z #305 Light Blue Metallic
    1972 240Z #110 Persimmons Red

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    Registered User Lazeum's Avatar
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    Head bolt torque is never related to gasket. It is always related to bolt specs.
    I would get new head bolts, either from Nissan or from ARP. It's a cheap insurance for the future. ARP set is around $120. Stock units are probably cheaper.
    If stock bolts are used, follow what's on FSM, if ARP's, follow their directions with their lube.

    The part in the oil gallery is called the oil restrictor. You have a second one at the front of the engine, close to the front cover to feed the chain and the tensioner.

    For your information, the restrictor between cyl #3 & #4 is the one we could increase to raise oil flow for the cam in racing or hightly tuned applications. I wouldn't mess with it, I'm just saying
    Last edited by Lazeum; 09-27-2013 at 10:12 AM.
    Matt - 72' 240z

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    HLS30A 17574 djwarner's Avatar
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    Double checked my 1970 Datsun Engine Manual and found the 32.5 and 47 ft-lb spec in three places.

    Interestingly, immediately at the start of "Install the Cylinder head assembly." there is

    "Note: a. Spread sealing agent over the cylinder block surface. Place gasket on it, and apply sealing agent to the gasket top."

    There is a similar note for the gaskets of the timing chain cover.

    I thought head gaskets were installed without sealant.

    Spent the afternoon de-carbing the cylinder head. Pistons and block in the morning.
    1971 240Z HLS30A 17574 L24-021025

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    Maybe they upgraded the bolts or tried to fix recurring problems, but 1972 has 2 turns ending at 54.2 ft-lbs, 74 has 3 turns ending at 61 high end, and 78 just shows 51-61, no turns.
    1976 280Z, with some minor modifications

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    HLS30A 17574 djwarner's Avatar
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    Ok. got to answer my own question. An E31 head with valves, lifters, cam and thermostat housing less manifolds and valve cover weighed in at 51.8 lbs.

    Head and cylinder block are no de-carbed, clean and flat for re-assembly tomorrow.
    1971 240Z HLS30A 17574 L24-021025

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