Bought a new cyl head...advice, please!

[jojax64]

I finally decided to buy an unleaded head, I got one from GS Jones.
I've NEVER changed a head on any car in my life, so what should I look out for? I'd like a fair idea of the pitfalls before I give it a go....don't want any expensive disasters.
Also, I fancied fitting a Duplex timing chain, so is this an ideal time to do both jobs?
Thanks in advance, peeps!

[Willie]

Assuming that you are reasonably competent mechanically, you should manage perfectly well. You must have a torque bar when refitting the head nuts and I would suggest that you ensure that the By-Pass Hose
(between the head and the water pump) is the THICK rubber type, not the thinner concertina type. You need a workshop manual for the proceedure and for the order of head nut tightening. Do not forget to
retighten the nuts after a couple of hundred miles.

[Peetee]

It is VERY IMPORTANT to loosen off all the nuts as recommended in a manual.
There is a specific order and you must loosen them off a bit at a time. To remove one without the others would almost certainly result in a warped head.
Obviously refitment carries the same rules.
It is nice when you get your first one off and look into the 'heart' of your car.
NURSE, GASKET!

[8009STEVE]

look into the 'heart' of your car.

Make sure you have used the correct amount of anesetic. Either STELLA (min 2 cans) or VODKA ( min large) HIC!

[Kevin]

If you dont have a thick rubber type of bypass hose to hand dont worry just use a piece of heater hose rubber as its exactly the same.

[Alec]

Hello jojax,

there is one problem in fitting a duplex chain, there are two (I think) screws that secure the engine front plate to the block near the bottom. With a simplex chain these are hexagon heads, but the duplex will foul these so countersunks crews need to be installed which entails countersinking the screw holes in the engine plate. There is limited access to do this, or else you need to remove the front plate and then do the countersinking.

Alec

[bigginger]

It is two, and it's a hell of a lot easier with the front plate out of the car.

[Axolotl]

It is two, and it's a hell of a lot easier with the front plate out of the car.

...but it can be done with it in situ. I used a flexy-drive on my drill to get access. Fiddly, but I thought it was easier than removing the front plate would have been.

You pays yer money...

[Axolotl]

there is one problem in fitting a duplex chain

LOL. That should read:-

"There are several potential problems in fitting a duplex chain"

Based on my experience, they are:-

1) Somebody's fitted a short fan belt, so you can't get it off without levering it over the pulleys, even with the alternator right at the short end of its travel .
2) You can't get the starter dog crankshaft nut undone, despite trying every trick in the book, several times .
3) When you finally do get it undone, you can't get the crankshaft pulley off without mangling it, even using your finest gear / hub puller . "Pull off the crankshaft pulley" my a**e.
4) The camshaft gear retaining nut was done up by the same gorilla that stripped all the threads on the small bolts holding the timing chain cover in place and glued them back with metal paste .
5) Drilling the above mention countersinks is an entertaining diversion .
6) When you've waited for fresh supplies of hardware to arrive with the engine in bits, and replaced the stripped bolts with nuts and bolts to put the whole thing back together, it still rattles when you get above 50 .

But at least the timing chain cover doesn't leak oil any more .

[stevey]

just on the subject of heads, ive decided that my rocker shaft needs changing, apart form slowly undoing all the heads in the right order is there any thing else i could do to stop the head gasket going so i dont need to take the head right off?

[Axolotl]

You don't need to take the head right off to replace the rocker shaft.

You do need to slacken all the head nuts, however, as four of them also help hold the rocker shaft in place.

The book says "sacken them one turn at a time in the order shown, until all load has been released."

Remember to drain the cooling system down to below the level of the head joint before you slacken the nuts, otherwise you will potentially get water into the oilways or cylinders.

Some might argue that there isn't much point in not taking the head right off when you've gone to all that effort, as you get to look inside the gubbins, you can check that everything looks o.k. and a new cylinder head gasket wouldn't go amiss.

Here's a pic. of the head bolt slackening / tightening order:-



Retighten to 40 lb ft.

[Dominic]

Retighten to 40 lb ft

Some people suggest 45lb ft - (25 lb ft for the smaller rocker nuts)and don't forget to re-torque after about 250 miles (or 12 fully hot / cold cycles)

[bmcecosse]

If you slacken the head nuts to do the rocker shaft - then you should fit a new gasket or risk failure in the near future. But - the good news is you can slide the old shaft out the pillars without disturbing the head nuts - and slide in a new one carefully re-aligning all the rockers as you go. It's not easy - but it can be done !

[stevey]

cheers people might just do the whole thing and replace the gasket as well, I didnt want to take the head off completely as I took the water pump of a mates car ended up with the block in pieces!!! Like you say going to that effort i might as well.