Thread: head bolts - help.

Oh dear. Sounds like someone got a little over enthusiastic in chasing oil leaks. Probably worth dropping the sump to see if the oil pump screen has a similar issue.

I think a full strip down of everything is needed. Also found a thermostat in the inlet manifold - id love to know who the previous owners mechanic was for I'd give him a sure kick up the clanger!
As I said it all looks good, can see the hone marks in the bores and there's almost no play in the pistons. Everything except for a few spots on the cam are a nice colour too.

Has anyone delt with camtech cams in sydney? I see the offer a 4.6 torque cam.

I'd be interested to hear how it changes the bottom end of a 4.6. They are quite a torquey motor already! More torque than a new Toyota Prado V6 with all the VVTi technology and almost as much as the new 200 series petrol 4.6 with all the bells n whistles - albeit at lower revs too.

If you could get more torque out of it at lower revs than what it already does then I am listening!

FWIW I ended up purchasing a standard OEM spec cam from Karcraft for a reasonable price... and it works! with new cam, solid steel rockers, new lifters and timing chain etc... all bog standard parts... I am quite pleased with the result.
I refilled the donk with Repco "running in" oil which has a high phosphorus content to bed the cam in properly. Used it for about 500km then switched to Castrol Magnatec 10-40 (on special at Supercheap). It's a very quiet engine now!
Benji, if you get the heads planed, make sure you measure the lifter preload correctly and if necessary purchase some shims to put under the rocker posts...
cheers

Originally Posted by Hoges

Benji, if you get the heads planed, make sure you measure the lifter preload correctly and if necessary purchase some shims to put under the rocker posts...
cheers

Good point Hoges. I found out the hard way when I built up a hot little 179 red motor back in the day! Bye bye studs!

Don't forget to bed the cam in too, varied revs from around 1500 to 2200 for 10 or 15 mins and plenty of heat. Don't boil it, just make sure it's warm and has oil pressure before you bring the revs up.

Okay so I've got both my heads off now (bent my 60cm Sidchrome breaker bar).

No real suprises except that piece of silicon. Also found a second thermostate in the inlet manifold (with no housing gasket; they've used roofing silicon instead).

So far i've figured out that they've used Holden lifters (the bleed lifters are 1.6mm shorter than the unbleed Delphi lifters), and the silicon on the leftbank has slowed down the flow enough to starve the rear 2 or 3 lifters, and also the camshaft as i've got slight heat marks on the cam with those lifters.

I few things i'm not sure of though - there's 7.52mm of play in the centre of the camshaft chain - seems excesive to me; but...

The play is so much, and the bottom cog of the chain has floated against the oil pump and caused scoring on the sides of the pump.

The other photos are because I don't really know if this mess is normal.

Hi

Those heads and pistons are covered in carbon which needs to be removed, you should pretty much have shiny metal on the top of the pistons and the combustion chambers in the heads

Careful use of a copper wire brush and cleaner usually does the trick, be careful not to scratch the heads or pistons. I am sure you will get plenty of tips here

You should also relap or replace the valves and seats if needed, IMHO that part of the job is best done by a professional

Check the liners for scoring as well, it's years since i have pulled a motor apart, and i am sure there are other things which will need checking.

Steve

One other thing, you may have just taken them out for the pics, but while you have the heads off, put clean rags in the pistons to stop any crap getting in there