Re-fitting LET head

[redxiii]

Those who have read any of the threads I've posted since registering here will realise I'm a bit of amature when it comes to this sort of thing, so even the simplest piece of advice can save me hours, anyway the heads off the cav (half of what should be in the engine bay is on the garage floor) and it's a bit of a mess but all seems to be down to the gasket failing and cylinder 1 filling with water, when I refit it,
1. are the head bolts of the stretch varity hence I'll need a new set, are vaux/other ones recomended and how much ?
2. head gasket, would a thicker one be worth it and what should I be looking for ? (car runs 15psi over boost and 12psi normal with a chip and a charge cooler)
3. Should I get the dremal on the piston heads etc and get them all cleaned up or leave them ?
4. Whats "honing" the cylinders and how can I tell if it needs doing ?
5. Can I buy a new oil seal for behind the dizzy as there was some oil in there ?
6. does the head need skimming ? as I'm not sure how to get this done and will it need all the valves etc removing ?

There's probably some more questions as well but these spring to mind.
Any help is much appreciated, thanks, Lee.

[redxiii]

Oh yeah, bolt order and torque settings, will they be the same as the haynes manual for the XE ?

[JamesG]

1.)yes you'll need new head bolts as they are stretch bolts..

3.) not really worth it unless your gonna take the pistons out

5.) would have thought so - phone vaux and ask

6.) did the car overheat? it's worth getting it checked for flatness at an engineering co anything more that 3thou across the head and it'll need skimming
valves don't need to come out to skim the head but you will have to remove the cams so that all the valves are closed...

[Laney]

Gav at Wallace Performance can supply you with new Head Bolts and a steel layered head gasket. Gasket is £25 + VAT and think the bolts were £18 but that may be totally wrong. THe head gasket is VERY good.

[Dave Hay]

1)- 3) as previous posts.
4) you cant tell if the bores need honed with pistons in. the "hone" dont know if right word here but is where the piston travels. just makes sure theres a tight fit between wall and piston/rings so nothing goes somewhere its not supposed to be. there is a ridge at the top and bottom the of the bore where u can feel this. i wouldnt have thought it was worth honing the bores unless ur piston rings went or you wanted a full rebuild.
5) if theres a seal and its leaking replace it.
6) always skim head if your gonna replace a head gasket. and if i owned a let i wouldnt cut corners cos ive read/seen too many of em blow up.

hth

[Laney]

If you do get the head skimmed (Should do) remember that doing so will increase compression which you need to avoid if possible. If you repplace the gasket to often (skim the head to often) then you will need to get a thicker head gasket. If its only been skimmed once or twice then a stanard thickness gasket will do fine.

[Laney]

Oh and Dave Hay, What do you mean blow up....The idea of suggesting that the C20LET may blow up is ridiculous. Just because Savage, Porous_Head, Barnes, Cavlad, myself and others have had slight misfortunes.

No in all seriousness you make a good point. You can't cut corners when it comes to the turbo engine (or any engine for that matter) cos they aren't very forgiving.

[Dave Hay]

lol, i got the email notification thru as i was reading this >> FAO Ex LET Owners

damn turbos lmao

[redxiii]

Thanks ppl.
Is Gav WallaceP on the board, or any other way of contact, website etc ?

[Dave Hay]

www.wallaceperformance.co.uk (banner on top of site too)

he does use board but dont think it would be easy getting in touch that way. his website has the contact info u need.

[ChrisReay]

Try Autovaux 01924 376003 for the parts you need.

Steel GM z20let head gasket £13.31 +vat (genuine)
Head bolts set of 10 £9.90 + vat

Or you could just stick to the c20let head gasket & get a complete head set for 45.24 + vat (genuine GM)

[redxiii]

Thanks Chris, what's a complete head set ?
and the z20let steel one is a proper fit, do you know what width it is ?

[ChrisReay]

Head set includes

Head Gasket
Head to turbo manifold gasket
Head to intake manifold gasket
Cam cover rubber gasket
Thermostat ring seal

Its quite a saving as a c20let head gasket alone from Vauxhall is 28.95 + vat.

Z20let gasket is a direct fit on coscast heads, not sure if needs slight mod for the KS head though. Gasket is 1.2mm

[Topbuzz]

[6) always skim head if your gonna replace a head gasket. and if i owned a let i wouldnt cut corners cos ive read/seen too many of em blow up.

I don' t understand, why do you need to get the head skimmed (bottom off) each time if there is nothing wrong with the head? If you have a perfectly good engine, remove the head, replace with new gasket and fit all back together again with new head bolts at the correct setting, shouldn't this be OK?

I thought thats the purpose of a 'soft' gasket, to fill in the imperfections of the metal-to-metal surfaces.

[Dave Hay]

i would imagine that would be OK, not good but OK, on N/A engine cos of the difference in compression ratios, i still wouldnt recommend it. but hey its your engine.
i always thought you needed the head skimmed so it was a perfect match to the new gasket. the old gasket may not be damaged but itll still be worn and wouldnt sit perfect. if your running high boost and lowered compression you dont wanna be taking risks if everything aint perfect do you?

just my thoughts, some1 that knows more than me may post ere too.

*edited cos i misread and fecked up my reply.

[muppetspor]

ive blown head gaskets on many different engines in many different cars and just re-fitted with anew head gasket and new bolts qithout having the head skimmed and never, ever ever had a problem.

i wouldnt do it with a all singing all dancing let like, but my 16v had it done, my 1400 etc as they cost me feck all

[JamesG]

TBH if you go to an engineering company and chuck someone a fiver they'll check it over for you and at least you'll know if it needs skimming or not. it only costs about £20 to get it skimmed anyway...

[redxiii]

Oh, if it's only a few quid I'll get it checked and done if it needs it, do they ever make a dogs dinner of doing it, I'd imagine that it's an exact science if we're talking 0.001 - 0.003 of an inch ?

[JamesG]

take it to an iso approved company (pretty much all of them) there machine's should all be calibrated so unless the operater is a real F**KWIT you'll be fine..

it'll only need skimming if it's out by anything more that 3thou across the head..

[redxiii]

Thanks James.

[TOBYC]

Interesting.......

im now about to put a coscast head on my LET.

should i get it skimmed before i fit it, i was worried about raising the compression and how do i know if its been skimmed before???

also what gasket should i use............bearing in mind its a standard engine is it worth me getting one of gavs steel jobbies or just a standard set from vaux.............

also i want to put the xe inlet cam in.......... will this be ok with out vernier pulleys for now??

[muppetspor]

pretty sure you dont need verneir pulleys to put an xe cam in. ive got one on mine without vernier pulleys and its no trouble. just time it up to std marks

[JamesG]

the haynes manual should specify a minimum height of the head, you'll have to make sure both the top and bottom of the head are flat then measure it..

i had 23thou taken of my XE head after i blew the gasket and overheated it!

[TOBYC]

any one know the minimum height please?

[redxiii]

I thought the only gain from an XE inlet cam was for high boost engines, something to do with the cam overlapping the exhaust one ?