Disco-Ron Posted November 21, 2014 Share Posted November 21, 2014 I'm in the process of fitting a 3.9efi auto in my 90. I figured it would be silly while it's on the garage floor not to do some work on it..... so I've removed the inlet and gubbins and removed the first head.... I plan on doing one at a time so to minimise the bits floating around... The first of possibly many questions is... It's originally a 14 head bolt engine, can I refit it with only 10, as I've heard that the outside 4 can be the cause of gasket failure..... Thanks Quote Link to comment Share on other sites More sharing options...
missingsid Posted November 21, 2014 Share Posted November 21, 2014 Yes, I have 3.9 10 bolt heads on my SD1 3.5, I believe that the other four bolts were a Rover idea and a bad one! If you are refitting 14 bolt heads it may be better to fit the last four at a lower torque to fill the holes to stop mud etc? Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted November 21, 2014 Author Share Posted November 21, 2014 Good point...... ta Quote Link to comment Share on other sites More sharing options...
landroversforever Posted November 22, 2014 Share Posted November 22, 2014 Can some explain why leaving 4 bolts out would help? Quote Link to comment Share on other sites More sharing options...
dave88sw Posted November 22, 2014 Share Posted November 22, 2014 Can some explain why leaving 4 bolts out would help? On the early V8s they had 10 main head bolts, 5 either side of the cylinders at equal spacings just as the late v8's did but they also had a further row of 4 smaller bolts that went on the exhaust manifold side of the head. It's generally thought that these 4 bolts actually tip the head as it's very common for the early engines to blow the head gasket into the valley (i.e. the opposite side to the 4 extra bolts). Later on in V8 production, the extra bolt holes were omitted from the head and block and Land Rover reduced the number of bolts to just the 10 main bolts. This seemed to solve the problem. The advice i've followed with great success is to torque the 10 main bolts to the recommended figure for the later engines and then fit the 4 smaller bolts to 20nm with thread lock just to fill the holes. Hope that helps Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted November 22, 2014 Author Share Posted November 22, 2014 Thanks Dave, that's what I will be doing.... Quote Link to comment Share on other sites More sharing options...
landroversforever Posted November 22, 2014 Share Posted November 22, 2014 Perfect, thanks Dave. It makes sense now! Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted November 25, 2014 Author Share Posted November 25, 2014 Put the first head back on last night. .. crikey it was scaryddoing the 180 degrees. .. darned tight!..... Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 25, 2014 Share Posted November 25, 2014 Bit late now but ARP head studs make for much more niceness doing heads as they massively reduce the opportunity for stripping/damaging the block threads. Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted November 25, 2014 Author Share Posted November 25, 2014 Maybe next time as I really didn't enjoy doing them what feels like too tight! Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted November 25, 2014 Share Posted November 25, 2014 I've always done them to a torque value rather than angle. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted November 25, 2014 Share Posted November 25, 2014 I've always done them to a torque value rather than angle. Don't quote me but I thought things like head bolts were a torque figure + X number of Degrees? Quote Link to comment Share on other sites More sharing options...
dave88sw Posted November 25, 2014 Share Posted November 25, 2014 I was of the opinion the angles were supposed to be more consistent, i.e. a 90 degree turn on a bolt is always the same, whereas a torque figure is effected by dirty/rusty threads etc. Torque figures are much easier though. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 25, 2014 Share Posted November 25, 2014 Nope. Head bolts are stretch or non-stretch. Stretch bolts take a torque, then plus degrees. Non-stretch just take a torque figure. Early V8s were non-stretch, later ones were stretch (suffix B onwards) http://workshop-manuals.com/landrover/v8e/torque_wrench_settings/engine/ But then you can just look at the bolts to see if they are stretch or not, stretch bolts have a narrower shank under the head of the bolt, compared to non-stretch. In theory you aren't supposed to use stretch bolts again, but some engine manufacturers state that if they do up to the first torque figure OK (in other words they aren't stretching and reducing the torque to turn), they are safe to use. Personally I would just ARP them, and I think it is is then just 60-70lb/ft on a nut rather than a bolt, which is much less breathe-holding, as you can't really knacker the block like that Quote Link to comment Share on other sites More sharing options...
Disco-Ron Posted November 25, 2014 Author Share Posted November 25, 2014 I used new stretch bolts..... but wish I'd got studs.... but then it's only a rebuild not custom build. .... Quote Link to comment Share on other sites More sharing options...
elbekko Posted November 26, 2014 Share Posted November 26, 2014 Just don't follow the ARP instructions, the torque they put in their manual is ridiculously high. Especially because they're finer thread too. Quote Link to comment Share on other sites More sharing options...
landroversforever Posted November 26, 2014 Share Posted November 26, 2014 A finer thread is stronger Ben, more contact area between stud and nut. Quote Link to comment Share on other sites More sharing options...
elbekko Posted November 26, 2014 Share Posted November 26, 2014 Yeah, but you're also getting a whole lot more clamping (and thus pulling...) force for the same torque spec. And IIRC ARP spec something like 110 ft/lbs for the head studs, that'll rip the threads right out of the block! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted November 26, 2014 Share Posted November 26, 2014 As above, I think they are 60-70lbft, nothing like 110. Quote Link to comment Share on other sites More sharing options...
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