Hi all
Doing a head gasket on a 99 4.0 & someone that does a lot of work on P38s has advised me that if the heads are skimmed then it can be very difficult to get the inlet to seal properly after because of how the inlet sits between the heads, that right? I've always skimmed alloy heads due to the fact of warping but never done a p38 head before. Any info greatly appreciated
Cheers

you only need to skim if head face is damaged ie around were fire ring sits or head is warped , but not fitting would depend on how much was skimmed off engine tolerances vary with rover v8s

thepartworntyreshop said:

Hi all
Doing a head gasket on a 99 4.0 & someone that does a lot of work on P38s has advised me that if the heads are skimmed then it can be very difficult to get the inlet to seal properly after because of how the inlet sits between the heads, that right? I've always skimmed alloy heads due to the fact of warping but never done a p38 head before. Any info greatly appreciated
Cheers

Click to expand...

from new RR says the reface limit = 0.50mm (0.02 in) from new dimension.

To check the new dimension (cylinder head at each end)
Engine numbers without suffix B
A = the lower part of the head = 23.9mm (0.94 in) Where the head bolts are)
B = the upper part of the head = 63.5mm

Engine numbers with suffix B
A = 22.94mm (0.903 in)
B = 65.56mm (2.463 in)

You can check if the head is warped with a very good straight edge.
for warping. across centre and from corner to corner.
Max warp = 0.05 mm (0.002 in)

Have you done this sort of work before? there are lots of things to consider.

Now, what everyone says is true, but why take an engine appart and not do a proper job?? Iv taken 25 tho off each head and the inlet went on perfectly fine and runs very sweet! That was a 4.0! I'm told by people iv worked with not to skim heads and i hate knowing that iv put an engine back together without doing a proper job! And an engine is actuly a very fine piece of engineering, when not pit back together properly things don't run quite rite and don't last as long! Its your choice! Do a proper job! People don't skim heads for no reason! Hope this helps! Tom.

tom1disco.300 said:

Now, what everyone says is true, but why take an engine appart and not do a proper job?? Iv taken 25 tho off each head and the inlet went on perfectly fine and runs very sweet! That was a 4.0! I'm told by people iv worked with not to skim heads and i hate knowing that iv put an engine back together without doing a proper job! And an engine is actuly a very fine piece of engineering, when not pit back together properly things don't run quite rite and don't last as long! Its your choice! Do a proper job! People don't skim heads for no reason! Hope this helps! Tom.

Click to expand...

no they skim them if they need doing not for the sake of it

jamesmartin said:

no they skim them if they need doing not for the sake of it

Click to expand...

+1 on that.

I have rebuilt many engines, many different types plus Land Rovers but mostly Jags and Astons plus others some to race spec. And only skim if necessary or as required.

On my p38 v8 I have skimmed a fraction over the spec because the heads had been badly skimmed before. So decided to save them and up the tune with lots of stuff to give more go. Involved valves guides studs and solid lifters, new but different pistons and loads loads more stuff. But don't go there its expensive and involved adjustable push rods to get the correct preload on the h tappets. Plus a a rebuilt bottom end to take it. Happy engine though. Camshaft was the secret to usable power

Even with a bit more skim the inlet was ok.

The reason I asked if you had done this work before is because there are quite a few things to consider before you undertake a V8 head job, What are your intentions?. I would be interested in your answer. Obviously you may just want to change the gaskets. But even that needs to be done correctly.

First thing to buy is a full gasket set. I would recommend composit head gaskets.

I would also recommend a tin valey gasket as the rubber variety tends (over time) to loose its rubber which clogs up oil galleys etc.

Recommended reading (as a starter) Overhaul Manuals 3.5, 3.9, 4.0, 4.2, & 4.6 V8 petrol engines Publication Numbers LRL 0164 and LRL 0004