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Engine build help request . Please..


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15 hours ago, Spit131 said:

Sorry Phil , I think you might have misunderstood me or more likely I did not explain well . I read that if you put the head upside down and fill a chamber which has both valves ‘ off cam ‘ or cams removed from head and then ideally use an airline to blow air up through the manifold ports towards the closed valves through first the Ex port then the In port whilst watching to check for any bubbles appearing from around the closed valve that should work ?  All though surely it would make more sense to turn the head the right way up/on its side so that you could fill the port up and then use your burette Perspex plate held against the head face and use the air line to force air into the empty chamber whilst watching down the water filled port for signs of bubbles escaping from the rear of the valve would make more sense ???

My apologies, I wasn't as clear as I should have been.

As Zetec has also said, I meant fill the combustion chamber and watch for leaks back past the valves (ie head upside down). One of the jobs of the valve is to seal the combustion chamber, so you test from this side.

Blowing air in through the port might show a leak, however you are in danger of lifting the valve slightly, so you can never be sure if it is a leak or lifted valve!

Phil

 

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Aso, Phil mentions a Perspex plate, which can work, fine and you can make from  any scrap piece.   But the plastic is light and easily lifted off the head face.

I prefer a piece of 6mm thick plate glass, nice and heavy!         Most glaziers should be able to find a scrap piece in their discards, and will make it safe to use, by drilling the holes, chamfering them, and the corners and edges, for not a lot.

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Yes Phil , I agree you need to ensure air pressure is less than spring pressure if testing by that method .

However as combustion pressure is vastly higher than fluid atmospheric pressure , that is why I was thinking that in an ideal world a fluid should really be forced under pressure from the chamber side as the hot gasses are on the power stroke on both valves and on the inlet valve on the exhaust stroke perhaps ?

 

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22 hours ago, Spit131 said:

Yes Phil , I agree you need to ensure air pressure is less than spring pressure if testing by that method .

However as combustion pressure is vastly higher than fluid atmospheric pressure , that is why I was thinking that in an ideal world a fluid should really be forced under pressure from the chamber side as the hot gasses are on the power stroke on both valves and on the inlet valve on the exhaust stroke perhaps ?

 

No, because the combustion pressure acts as a "clamping" pressure. Same as your cylinder head, if you don't tighten it down properly, the gasket will blow out and it leaks. Properly tightened down it doesn't leak (or at least you hope so :wink: ).

What you are doing with the valves is testing them at the lowest clamping pressure, which is atmospheric. If it seals, you know it will seal at the higher pressures.

You are thinking about it in terms of a leak test like you would on a pipe, or your engine cooling system. For that you are right, pressure is good! The valve test however is testing the seal, which is essentially the opposite. Prove it works in the worst case scenario, the it's good for everything else.

I hope my ramblings make some sort of sense!

Cheers,

Phil

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More than mine Phil I’m sure .

Omex turned up yesterday .

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Flywheel is overdue . 

pistons hopefully on their way soon .

The probate sale of Debras parents house still seems to be on track , numerous architects and builders have accompanied the owners on several visits so they must be serious . They are looking at completing early September so I will be stepping up looking for that BIG garage attached to as nice a house as our little money can stretch to ! 
it has dragged on for two years now thanks to Brexit and Covid so it will be a massive relief if it happens .

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It’s desperately needed , at present I have a stack of boxes in the kitchen , a stack of boxes in the sitting room , cylinder heads on the stair case and I can only just squeeze into my tiny garage once I move the lawnmower , hose reel and other stuff out of the way ! 
I realise I will have to keep very disciplined and organised with a bigger space but it is my only hope . 

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Yep that sounds untenable! I've got a very strict 'no lawnmowers in the garage' policy. Garages are for car bits, and everything else can find a different home. Of course, that's dependant on their being a different home for it so hope you get some space for that soon!

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I am currently looking at a couple of local companies regarding block preparation initially .

The first is CCK historic in Sussex .

I sent an enquiry but no response as yet ,

https://www.cckhistoric.com/
 

The second is SMD in Sheppey in Kent .

The owner is a friend of GC and highly recommended . 
 

https://www.smdracing.co.uk/

Both look very capable , might come down to who has the time ?

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52 minutes ago, Spit131 said:

I am currently looking at a couple of local companies regarding block preparation initially .

The first is CCK historic in Sussex .

I sent an enquiry but no response as yet ,

https://www.cckhistoric.com/
 

The second is SMD in Sheppey in Kent .

The owner is a friend of GC and highly recommended . 
 

https://www.smdracing.co.uk/

Both look very capable , might come down to who has the time ?

Hi Matt, I see from your first post that your in south-east London right? I'm near Waterloo / Elephant myself. A pal of mine has just had a rebore by Gosnays up near Romford, and was impressed with the service. http://www.gosnays.co.uk/acatalog/

I've just discovered a place called Motortech in East Dulwich, which is just round corner from me. Had a head skim and valve guides done so far, which isn't much but standard seems high. I'll be taking a block and crank to them for a rebore & grind sometime soon. https://goo.gl/maps/GTqnhjS5hjj5F4tv5

Pete

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