What tests to do on rebuilt motor

[69alfa]

I am rebuilding my Twin Spark and am wondering what tests I can do to check my work before I start it up. I plan to do a leak down test before the motor goes back in and a compresson test after it is in.
Other than liner to deck hight is there a good way to check the liner o rings? Filling it up with water should work ,I may try that before I put on the oil pan.
By the way I did check the valves and they were all good.

Thanks

[Tifosi]

Leak down and compression would probably be a bit of a waste of time as the rings haven't been seated in yet, (if you replaced them), and can give horribly misleading readings until they do bed in.

[PSk]

You can check the valves are seating properly by a sort of leak down test. There is a site where the hoster does this and explains the concept ... I'm trying to remember his name: Mike somebody.

Pete

[dan farmer]

maybe you're thinking of Mike Valant. His website is http://engr.smu.edu/rcam/cpm3v/alfamain2.htm

-df

[DanP]

Hey, have some confidence. If your cam timing is right, fire in the hole!!!

Dan

[PSk]

Quote:

Originally Posted by dan farmer maybe you're thinking of Mike Valant. His website is http://engr.smu.edu/rcam/cpm3v/alfamain2.htm -df

[slyalfa]

Read up an how to break it in to seat the rings.
do not let it run on jack stands. when the time come to fire it up be ready to drive it, to do the first part of the break in where it counts the most.

In the past I was way to soft on a rebuilt motor and I would never get the rings to seal right.

[pepiot]

pay attention to the primary chain , with the actual new chains it is not rare to have to try 5 different chains , they are poor quality parts generaly , its very important to have very small clearance ,as it gives you the precision for the timing (ignition and valves ) with that new chains it is not rare to get 10 degres clearance , and its realy very much , in that case due to a very little thing ,you will have a bad engine . ON ANOTHER WAY after 30 years working on that engines ,i never saw a chain broken ! it means that in some cases it could be intresting to use old primary chains , even if i would much prefer to use new ones !

[slyalfa]

pepiot,
how and where are you geting clearance readings?
I got one chane that did not have a master link and that was fun.
but the slack is set by the idle gear and the timing of the cams is set with the lines and moving the bolt from hole to hole. so I am at a loss as to what this 10° reading is.
can you explane how you take the readings?

[pepiot]

ATTENTION, i spoke about primary chain , not the long one , as there is no way to change the tension of it it is very important to get the smaler clearance between cranckshaft and the primary axle , if when you move(clockwise and ant c w ) one of the two primary pinions , the other one do not move for a certain number of degrees ,you will obviously find that error
when you will try to get all the correct timings of the engine .
I said that because i am rebuilding professionaly a lot of that engines in my country ,and more and more often i get that problem due to the poor quality of the rebuilded new items !.IT IS NOT because it's new that it's good unfortunatly !
firstly when you fit the chain ,it as to be very difficult to install , secondly : put the couple of pinions in the bearings of the crankcase with the chain fitted
and try to move one opposite to the other , if you can move one pinion for several degrees , it will be very enoying !
concerning the secondary chain there is no particular problems
anyway i would like to apologise for my poor english wich does not allow me to be very clear in technical explainations !