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Torque on head

My newly rebilt engine suffered a head gasket failiure on one of its test runs, not a big problem and it will teach me to re-use an old head gasket. However when I did the nuts up, I followed the old rule about do-ing them up with the austin spanner so as not to over stress, but when I took the head off today a quarter of a turn had the nut loose. My gut feeling is that they perhaps should have been a tad tighter. Though I am confident the old gasket is the main source of trouble.

My question is how tight it tight? does anybody have a torque figure I can use, or were they tight enough?

For the record, all studs except one are standard new standard size 'severn workshop' items, the other is a home made stepped job to suit the 3/8 UNF thread in the block, This stud used to be a Landrover spring shackle bolt, and yes it was new before I vandalised it.

I picked up a new Payen gasket last night from Newport and 20 minuits should have the job done, just want to be sure my nuts are tight enough.

Re: Torque on head

Hi Hedd,

22lbs is what I do them up to, make sure you start in the centre and work out...

A good friend of mine soaks his old head gaskets in water for a while which expands them before re-using them...I always fit new, I found the Ozzie ones with black sticky-stuff on one side very good indeed, the choice is yours.

Cheers

Ruairidh

Re: Re: Torque on head

Many thanks Ruairidh

Hedd

Re: Torque on head

Nothing wrong wuith reusing the old head gaskets. Austin recommended it. I'm still using the original 1927 gasket and its fine, just make sure its well dosed with graphite so it comes off clean next time. Mind, they don't make gaskets like they used to. I never used a torque wrench until I was persuaded to recently, just used the proper spanners. Took them to 20lb-ft then checked with normal spanners. Seems I must have had them about right all along.
Martin

Re: Re: Torque on head

I've had a harder look at the old one, the leak was into no 1 cylinder, and best guess from the water 'hole' in front of it, The block is less than perfect there but has always been like that and never yet a problem, however the gasket also looks like it has in the past been tightened down on some 'sh1t' in the same area with lots of dimples in the copper sheet. I suspect this is the real problem

I have always used 'plumbago' on cylinder heads, a steam engine term for a mixture of graphite flake and steam cylinder oil (680 + tallow), its filthy, sticks like sh1t to a blanket and leaver your hands black for days, however its good stuff, 100% better than copper ease or grease. It is on all the threads on the chassis. Brake pivots, everywhere in fact, even the nylon bushes I made for the brake shaft, and the taper on the radiator drain tap!

Saying that I'm going to use Hylomar on the new gasket, on the basis every little bit of sealing helps.

Re: Re: Re: Torque on head

Hedd

As a steam man I'm sure you have made sure everything is flat?
I know everyone says it but parts need to be flat to seal no matter what gunge you use. When I recently stripped mine down I lapped the head and the block faces on a surface plate, the block face was not flat near were the gasket had just started to show signs of failure. After a fair bit of elbow grease I managed to hand lap it nice and flat.
It seems OK now although I've probably only done a few hundred miles since.

Steve

Re: Re: Re: Re: Torque on head

Block is flat, no idea about the head.
I remember watching father clamp one onto a milling machine as a boy, long and short of it was that it deflected very easily, he gave up and didn't bother, if they are that flexible it doesnt need to be flat, it will pull to the block with the head bolts.

I will endevour to post a picture of the dimpled surface of my second hand gasket......

Re: Re: Re: Re: Re: Torque on head

Hedd,

I skim the heads by bolting them throught he spark plug holes on to the faceplate on my lathe.

If you clean the top of the head up first you wont have any problems.

I have machined off sod all from some heads just to make sure they are clean normally work in 2-4thou steps.
Sharp carbide tool with the lathe on about 45rpm and a fine feed. Takes about 10mins for a pass so i normally walk off and leave it, you can tell where it is in the cut from the rhythm as at cuts across all the holes and combustion chambers.

Did one for Ruairidh a couple of years ago and removed all the rust pits whilst leaving slightest rust stain in the surface.

Only ever machined to remove rust pits round water holes / increase compression ratio, never had to do one because it wasnt flat.

Regards

Rob

Re: Re: Re: Re: Re: Re: Torque on head

Tip I was given for tightening heads was to tighten, as Ruairidh says, to about 22lbs gradually, following the recommended tightening sequence. Then run the engine up to temperature, switch off let it cool down and then re-tighten as necessary. Then recheck after the next 50 or so miles and then after a couple of hundred more. It is surprising how long it can take for a head/gasket to settle down.

Re: Torque on head

If you absolutely must use glue on your gaskets, Wellseal is much better than Hylomar. Seals well, stays flexible at higher temperatures, breaks easily when needed and is less prone to oozing out, so doesn't produce sticky globules to gum up oilways if you apply a bit too much.
Martin

Re: Torque on head

Hedd,
22ft.lbs for me as well so there's a consistant message across a number of us. Make sure the stud holes in the block and head are lightly countersunk to take up where the joint doesn't quite fit and rides up the studs - 1950's Jack French advice. Take it down in stages though starting at about 15, then 20, 22, 25 and then keep going round until there's no more movement.

I've heard this thing about reusing head joints before. I can understand it to get you home but they're not that expensive (still probably about the cheapest of any car?) so I always use new. Old joints may be reuseable (but do you want to take the chance), they will have asbestos in them, Compressed Asbestos Fibre, CAF in Industry parliance. I work in a Power Station, asbestos was finally banned about 4 or 5 years ago, CAF was the final bastion because there isn't anything as resiliant (returns to its original shape). It is nasty material obviously but good at what it did. We've had a few problems with the replacement materials, they're less forgiving of other problems on the two faces being joined. If your reused gasket/joint was an asbestos free one then I'm not surprised its failed. You might get away with it with an old one

Another thing about flatness. The studs are only 5/16" and very short. They're there to hold it all together, they're not strong enough to straighten out something that's dished. The tension in the studs/nuts is only to clamp the joint. If you imagine them as 14 springs holding the head on, very little movement loses the tension from the nut as the studs being short and slender at 22ft.lbs aren't stretched very far - you said a quarter turn. Any relaxation loses the tension. Overtightening can make things more liable to blow!

Hope it works this time, there's nothing worse than doing a job twice!

Dave

Re: Torque on head

Hedd,

I personally have never used any sealant on my head gaskets, I do always fit a new gasket however.

I do big distances in all my cars and have never really suffered any major head gasket failure. I would skim a head if I was in any doubt about how flat it was, too much hassle to keep taking it off, replacing the gasket, and then inevitably snapping the last stud, only to start all over again.

Cheers

Ruairidh

Re: Re: Torque on head

I used to big miles untill the engine expired, Rugby, last trip was home (north Shropshire) from Wiltshire with a poorly bottom end. never had a head gasket go until this one, and it lasted less than 30 minuits of running!

By the way, have got my straight edge out, head is flat!. The second hand gasket was of unknown parentage, and probably the culprit

Re: Torque on head

Torque was covered some time ago, on the Forum and the main recomendation was 22 - 25lbs with CLEAN THREADS - NO Copper ease etc.

At the time 2 - 3 years ago, I had done mine up to 25 with Copper Ease and had the feeling one or two studs were stretching - The Forum told me off for using Copper Ease........, I have not touched the head since, fearing if I loosen the nuts something will ping, then again there have been no leaks either. Done about 7,000 miles so far.

Sandy

Re: Re: Re: Torque on head

I agree with Ruairidh, particularly about the use of new gaskets. Somebody said earlier that Austin recommended re-using the old head gasket - yes, but that was when one had to pull the head off every 2 to 3 thousand miles as decoking was so necessary. Now with modern fuels this is old hat, one should look to rebuilding an engine to last as long as possible, so the fitting of new everything, including studs, nuts, checking for flatness on head & block etc, is the go unless you're a masochist. Cheers, Bill in Oz