Compressions 12hp post war tourer.

[David2021]

I checked my compressions again today. Engine hot, running well. Results again showed about 55psi on all 4 cylinders, well no 4 just a whisker more..
All seems a bit low to me...even my Austin Sevens got into three figures! I am not minded to take the head off... yet. The engine is smooth, pulls well and sems to have "sufficient" power, no ball of fire though. I will try the Rover engineers top gear driving test mentioned in the Workshop Manual!
Maybe a job for a few quiet winters evenings Any ideas? Valve clearances? I have never checked the tappets.

[luli]

It should be 120. Are you sure your tester is OK?

https://lulis.org/2014/08/07/%d7%a8%d7% ... %9b%d7%91/

[David2021]

Same one as used on my Sevens not so long ago!
I'll try it on another car. ...but I fear it's ok☺

[luli]

"Eating oil"? smoke from the exhaust? fumes from the breather or the rocker cover? Do you have a vacuum gauge? low vacuum on idle is indication of valves or rings issues.

[David2021]

Burns little or no oil. Pint to 500 miles perhaps - last year's Luxembourg trip used about a litre. No fuming rocker!
I don't have a vacuum gauge.
If I find the compressions on my ZA Magnette are healthy on this gauge I will check the tappet clearances....I see in the Handbook that these should be .010" hot (I hate doing that job... get the engine hot, then strip bits off to get at the rockers....by the time you get to the last ones everything has cooled down) I note Mr VH Watson's usually trustworthy book suggests 0.005"; also hot! Hmmm.
I will go for the handbook settings!
My starting handle won't engage (sagging front engine mountings I think...I have new ones ready to fit) so it will require a grandson to push in third gear to turn the engine over! Or maybe I can lift the engine enough to engage the handle....
Certainly my engine has very quiet tappets.

[HAD501]

David
10 thou tappet clearance is correct for 1938-47 engines. 5 thou applies to earlier cars.

[David2021]

Thanks!
We will be at the Jubilee on the Saturday...Maybe I will have a result, by then...or leave well alone until after it!
David

[David2021]

Hope to see you there ..tappets re-adjusted or not!
KKM 12