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Thread: head bolts - help.

  1. #31
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    And please use ARP studs on the heads on reassembly. They are 7/16, 200,000psi set, available on order pretty much anywhere. Midel Fabre in Sydney have about the best prices I've found.

    The ARP instructions will tell you use either their moly assy lube or oil, never another brand moly lube. I've always used a generic assy lube and never had an issue but seen a few with oil. 80lbs with moly in 3 steps, go finger tight in sequence then 20, 40, 60 & 80. Or it's 85lbs with oil.

  2. #32
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    Thanks again Hoges, very helpfull.

    Where you say to cover the cam bearings with assembly lube, do you mean oil, or breaking in lube that goes on the lobes? I'm using the old bearings shells (obviously), so would they need to be 'cut' in to the new bearing journals on the cam?

    Clubagreenie, I've gone against the advise of a few here, and on other forums too and used stretch bolts. There's two reasons for this -

    I've heard the nuts should be done up to 70, 72, 75, 77, 80, 85 and even 90NM - I think ARP have revised their torque settings since they've now got a specific 4.6 part number (previously as I understand there was just one part that was designed on a 3.5), but that's a lot of variability on an engine that will be taking us to some pretty remote places.

    And secondly, NM isn't a measure of the compression on the head, it's a measure of the friction in the thread and under the head of the nut; and that friction varies a lot - I did a quick test with and without oil to 30 foot pound and ended with a 17 degree difference! I think Rover went to stretch bolts to get a more uniform tension on the head, and when doing the bolts up, all the bolts started stretching (you could feel it) within a degree or two of 40 degrees on the second 90.

    I do think the bolts should be a bit longer though, more thread has got to be a better thing, and if I had a 4.0 litre I would definately use the studs.

    Swings and roundabouts I suppose.

  3. #33
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    Aug 2007
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    I thought about using oil but because it was going to have to sit for a month, I plastered them with assembly lube.

    Have you remembered to pack the oil pump with petroleum jelly to prime it?

    I forgot to do this...however (there's always a 'however'). I firstly prefilled the new oil filter then fitted it. I had discovered that the M12 x 1.5mm threaded cap opening sitting just above the oil pressure relief valve on the front cover can take a threaded pipe to which I connected a 1/2" polythene hose and so pumped 2 litres of oil through it using one of those plastic centrifugal pumps fitted to a cordless drill ...

    very soon I saw oil dribbling from the rocker shafts etc .... When I was ready to complete the 'closure' I poured another litre or two from a jug all over the rocker gear then fitted the rocker covers. When I was almost finished I poured the rest into the normal filler hole. When I started the engine, the oil pressure rise was effectively "instant" although the lifters took a a few seconds to take up and stop rattling...

    BTW I used the ARP studs... 3 levels to 65 ft lbs. ARP 'guarantee' their 'lube' material properly applied provides even torquing and that there's no need to retension the heads with the Elring head gasket. I used a Payen metal valley gasket.
    MY99 RR P38 HSE 4.6 (Thor) gone (to Tasmania)
    2020 Subaru Impreza S ('SWMBO's Express' )
    2023 Ineos Grenadier Trialmaster (diesel)

  4. #34
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    To add to that, prior to fitting the lifters it's advised to leave them in a bucket overnight with engine oil covering them. In the morning use a spare pushrod to "pump" each lifter a dozen times or more while still in the oil to pump out any air and effectively prime them.

    This will save them dry-starting and becoming prematurely noisy.

    Cheers
    Keithy

  5. #35
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    Benji,

    I've tested tty bolts from both Toyota (30+ sets) and Land Rover (20 sets). Keeping the reply as brief as possible the variation in final tension, tension after static and running time, amount and location of stretch on the bolt all were outside what I'd conider to be reaonable variation. Without figures in front of me, and specifically looking at the Land Rover product, approx 20lbs variation in tension after static rest. Up to 30lbs variation after a running in period and even one bolt less than finger tight. Stretch should occur in the plain section of the bolt and not the thread and certainly never in the contact section damaging the formed threads in the block. As an aide I always helicoil all thread in alloy blocks and those that are "wet" in iron blocks.

    The Toyota product had less variation and no deformation in critical thread areas but still was not acceptable.

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