246 leak down test

I'm struggling to get my engine to run nicely , especially on the front two cylinders both not pulling their weight so I decided to do a leak down test...I put 100 pounds into the first gauge and then turn on the tap to allow the pressure to enter each cylinder at a time and all except one read 100 / 100. So that's sounds wonderful except that with rocker cover off I hear a lot of hissing air coming out of the timing chain area....I assume it coming out via the crank case which means it must be passing the rings so how come it still reads 100/100. ????

Am I doing this right ??

Is it normal for it to gush air up from the timing chain area ??


Advise and comments please..
Thanks

 

Yes...I think it's impossible too ...I have an aircraft type differential tester ..I put each cylinder at TDC. And all except one reads 100/100.
The do one reads about 100/80 and I can hear hissing coming from that relative carb so I guess the inlet valve has a bad seat...at the same time I'm hearing a lot of air gushing out of the timing area...
But I'm still getting 100 /100 and
Is it normal to hear the air coming out of the timing chain area...with rockers off...

The engine runs badly after a top end overhaul ...

 

Oh...yes the compression tests shows about 140 max on all pots

 

What I dont understand is ,yes I have a reasonable 140 ish compression when cold and turning a bit slow so that tells me that rings should be Ok BUT is it normal to hear a real gush of air coming from the chain area deep down...surely this means that when the rocker cover is put back a lot of pressure must build up ?? in crankcase and force oil smell or worse....is that normal ?? ...I mean it sounds real loud but the leak down tester harcly moves....

comments pls

also what are those two little air stems coming out of the inlet manifold for ?? during testing I assume I should block them ??

 

Hi... The inlet manifold has two little extrusions with minute holes which go via plastic tubes to the big carb filter.....well mine does anyway.

I am still pondering what Im doing wrong with the leakdown test,,,Im just pumping 100 pounds into the spark plug holes.....the first gauge reads 100 and the second about the same....when I rock the crankshaft back and fourth at the same time it almost pulls the socket extension out of my hand and of course the pressure drops either side but back to TDC and back to 98 it goes.....
I accept Im doing something wrong but not sure what yet...I will get there....eventually I hope...

Thanks for your comments I appreciate ...

Oh and POT...well...its been a Pot (Cylinder) since i started with motors about 55 years ago..(In England) ..but maybe nowdays that terminology has faded......but talk to any old boy.....its still a Pot...Cheers...From Sunny Portugal....