Hi all,
Don't know if anyone can help me with this but I am at wits end and probably need to pull out the motor but having a break from it for now as I have spent many weekends wasting a lot of time and getting no where
Rebuilt motor all new parts, below is build specs and trouble shooting sequence I have been through.
SPECS
Cooper S 1275
- Block original motor, machined by Graham Russell.
- Crank 1275 from GT or 1100S (cant exactly remember, Graham sourced it for me), original out of Cooper S had a crack and failed crack testing.
- Pistons GR 40thou fitted to conrods by Graham.
- Cam Cooper S original, ground by Graham to slightly advanced Cooper S grind.
- Head original, Police size inlets, SS seats by Graham, bronze valve guides by Graham.
- Carbies standard 1 1/4 Cooper S fully rebuilt.
- Vernier adjustable timing gear, cam in at 105 degrees.
- Oil started with shell 50 as cheap to flush motor out.
TROUBLE SHOOTING
- When first starting motor fired up beautifully not problems at all, after about 45 seconds started blowing oil smoke, a lot of it, particularly under medium revs.
- Following this I rebuilt the PCV valve as diaphragm rubber was hard, thought I was onto it, not luck, still blowing smoke when once warm. It did improve it slightly when idling. But soon as rev smoke back.
- When driving it smoke is consistent and worse when off throttle and then back on, and when plain on it and worse at revs.
- Compression test on all cylinders is fine, Somewhere between (195 and 205 over the 4 cylinders, wrote it down on piece of cardboard at the time).
- As old vehicle, drained all the fuel out as was some old varnished fuel there, completely fresh fuel, no fix.
- Changed inlet valve guide seals to viton steel casing ones, sealed case onto guide with gasket maker sealer. No fix.
Changed oil to Penrite expensive oil for Mini, no change. just took a bit longer to start when warming up.
- Last ditch effort did same to exhaust, no fix. There was a fair amount of dirty exhaust oil blown up under seal from cylinder.
- Apart from the smoke the engine runs beautifully, very quite, smooth, plenty of pulling power but is using around 3mm oil on thee dip stick over 3kms.
- Oil is not building up in the top of head, have checked that, so draining away fine. I have also had the car idling facing up hill, and under revs still blows smoke.
- Graham installed new Cam bearings, and I checked the oil galleries when assembling and everything seemed fine with compressed air flowing through.
- I can only now assume there is something wrong with the pistons? I installed them the same as any other motor I have built, they dropped in fine, used piston ring compressor that I always use. I pre-checked the compression ring gaps and they where bang on. The only slight concern I have is the top and bottom oil rings that sandwich the oil diffuser ring where not particularly springy, felt quite light and where easy to get started in bore compared to compressions rings. One piece oil rings I have fitted in the past seem to have a bit more pre load to them, but I do not know if that means any thing??
I think the engine needs to come out and see if anything wrong with bottom end but thought I would ask Ausmini community if they had any other thoughts as feeling a bit over it at moment!
I had original motor running when I first got the car and it wasn't blowing any smoke and its ring and bores where completely stuffed. I just cannot understand why this brand new motor would be blowing more smoke than a bat mobile on a fast get away
