12 replies to this topic

[crn1969]

hi I am going to get head skimmed before installing new gasket,what about the top surface of the block?will that also need machining or can I just clean it? if so what method of cleaning would you suggest ?this is a first project so need all the advice I can get cheers.

[MaxDempsey]

As the engine is cast iron it's really unlikely it will have warped so shouldn't need a skim on the block face, I used a fine emery cloth with WD40 to lightly clean the surface. It is important to use a block when doing this as you don't want to clean it unevenly and take away the 'flatness' of the block. I blocked off the oil holes and the bores with cloths to save anything falling in them. I'm afraid I can't remember what grit emery cloth I used as I just asked for some from the engine builders I do work at.

[crn1969]

ok cheers max ,would you know of a reputable machine shop to get head skimmed in Essex ?

[Carlos W]

ok cheers max ,would you know of a reputable machine shop to get head skimmed in Essex ?

 

Not in Essex, but Dartford Rebore is not far (depending on where in Essex you are)

[Cooperman]

It is unusual for a head to need skimming as the head is also cast iron.

Just get a flat block and some emory cloth and go over the surface of the head and you should find it cleans up very well. It is normally only necessary to skim the head if the head gasket has failed and water erosion has taken place, or if the compression ratio needs to be set correctly and the chambers are a bit too big - like after gas-flowing the chambers.

[crn1969]

ok nice one .old gasket was in good nick so may get away with cleaning it will try first to see how it comes up.was just thinking if it don't cost too much its worth doing.any tips on a good way to check flatness when cleaned(without the use of engineering equipment)?

[Cooperman]

It would be incredibly unfortunate if a head was not flat unless the engine had got so hot after a gasket failure that the engine seized or almost seized.

A cast iron block almost 3" thick is very hard to warp and the heat required to do so is huge.

The only time I've had to have a head skimmed was after a failing head gasket had allowed water to sit between the block and the gasket for long periods of time or when deep-seated rust had corroded the head face.

I really advise you to use emory cloth on a block about 5" x 3" to clean the head back and ensure it is acceptably flat. I'm sure it will be. Then, assuming it's a 1275 engine, use a BK450 head gasket - that's the black one. The gasket is intended to be capable of taking up small imperfections.

[MaxDempsey]

B J Ashpoles, in Bishop's Stortford is just outside Essex so depending where abouts you are it may be close, will skim heads, but as cooperman says its unlikely to need a skim, if you get a known flat edge (maybe a block of steel) and put it along the face along the middle of the compression chambers you can roughly check for flatness by getting down so the face is at eye level and looking for light underneath the block.

[crn1969]

Thanks a lot guys really helpful will definitely get some fine emery cloth and save myself some money.was running okay before taking engine out so hopefully will be okay.gonna be doing some other bits soon also so will be back on here .many thanks.

[Cooperman]

We will all be pleased to help in any way we can.

Good luck with the head work.

A tip if I may. It can be a good idea to remove the manifold studs from the head and replace them with 5/16" UNF x 1.25" long hex. head set screws. If this is done it makes it possible to remove the head very easily in future as the manifolds can be left in place and you just take out the bolts and slacken off the engine steady bar and lift the head off after undoing the head stud nuts and rocker shaft.

[russo]

I'm assuming that the studs have been removed from the block. This must be done as over time the block threads stretch and become proud of block. These must be flattened so new gasket can sit flat on block.

[crn1969]

Excellent tips thanks

[JPN173]

Hi there i know of an engineering company in Romford called Gosnays. they have a website http://www.gosnays.c...log/index.html. hope it helps