Bought this engine last weekend knowing it is down on compression Equally across all 4 cylinders (~60 Psi) originally i thought piston rings but i made up an adapter and stuck the air line in and with both inlet and outlet valves fully closed it was blowing out of the inlet port, quite badly. the gauge on the compressor was showing 40 psi, no more.
So i thought valve seats, whipped the head off and found a nice and clean bottom end


This was the adapter i made


these are the valve seaats and valves, a little manky but don't look toooo bad to me?!





so now i'm confused? Maybe weak valve springs? even though they are cooper S double valve springs ?

As a side, Its a fookin wonder they get the head gaskets to seal on these things, 3.2mm between bores



oh and by the way, its an A series, going in the mini

 

Spin the inlets in a drill see if they bent

 

thats a good point actually, 2 of the valves, on the same cylinder, were tight in the head, to get them clear of the guide i had to tap them out with a drift

 

Prob bent or sticking open.

Wierd that its equal down on all four (that thick old copper head gasket?) its not designed to be turbo charged is it (hence lower comp)

Are you testing compression with a compression gauge, u wont get a proper reading off a compressor.

 

TBH i didnt test it myself, just going off what i was told when i bought it. i'll try the drill trick now, back in a mo.

 

Isnt it a cylinder leakage test you want?

 

Another good method is to put all valves back in (springs collets etc) turn it upside down and pour petrol into head and see if any weaps out of inlet or exhaust ports (proving leakage)

 

well its definatly leaking from the valves, with 40 psi in the compressor and both rockers rocking it was blowing a lot out of the inlet port so either the valve seat is shot or the valve wasn't seating properly? unless i'm missing something?!
just checked the valves in the drill and they seem straight although they seem strangly worn, some bits are shiny and some dull, pluss theres a bit of a lip on the stem

 

that's too much hard work

 

Those seats are crap to be honest, as is the valve in one piccie.
It might pay you anyway to re-anneal the headgasket first, but this isn't the problem, just might as well while it is off.
If you have pressure going in and then coming out through the port the only connection point is past the valve.
The dull shiny bits tell you the valve HEAD is bent, so new valve needed, not expensive on a series, and bloody good engines as well, what head is it 12G940, 12G295 etc
tabetha

 

PM chip he is quite knowledgeable about the A-series engine