Engine swap - measuring the change

[welshrat]

Well perhaps not shocking but oil light is on when ticking over at 35lb and used to having 40lb plus. More of a refresh than a rebuild, main and big end shells (standard size), bores just honed as appeaered to be in really good shape, new oil pump. Pressure drops when water temp gets up to about 70 degrees C, engine filled with 10W-40, is this a bad option?

[bmcecosse]

Yes - bad option....but not going to make much difference. Many will tell you to look at the relief valve - so you may as well do it, but unlikely to be the answer.......I'm afraid. New shells are almost always a waste of time on a 1275. For not much extra you could have had it reground and so 'like new'.... I'm wondering about the 'oil light on' at 35 psi?? Either the switch is set very high (actually a GOOD thing) or the gauge is reading high - a v BAD thing....... If the engine is just running away - not driving the car - you can expect the pressure to drop even lower when it has to do some work.

[chrisryder]

Why 10w40?!

No wonder it's low on pressure. The thin oil will be finding it's way out all over the place. 20w50 is correct, and thick enough to keep good pressure.

[bmcecosse]

Yes - we go over this time and again - but frankly, it only makes 5 psi improvement - and this engine needs a LOT more than that.....

[welshrat]

Why 10w40?!

No wonder it's low on pressure. The thin oil will be finding it's way out all over the place. 20w50 is correct, and thick enough to keep good pressure.

When you say finding its way out do you mean leaks as have not spotted a drop as yet.

[chrisryder]

Internally. Between the bearings and the crank, it'll be falling into the sump. You often get low oil pressure on a worn engine as the oil can find its way out and into the sump again. Thin oil will have the same affect.

[welshrat]

Will change the oil and check the relief valve, spent a lot of hours swapping the motor and fitting the new bits so happy to try anything at the moment. Will need some recovery time before I attemp another engine change, getting too old for this sort of stuff, feel like I have had a good kicking, hard work on your own with just an engine hoist and trolly jack.

[bmcecosse]

You have an engine hoist?? That makes it easy!! The engine would be fine for a while with standard parts fitted while you rebuild the one you took out - no point trying to get extra power from an engine with poor oil pressure.

[welshrat]

You have an engine hoist?? That makes it easy!! The engine would be fine for a while with standard parts fitted while you rebuild the one you took out - no point trying to get extra power from an engine with poor oil pressure.

Well not sure the engine hoist makes it easy, thirty years ago it was a walk in the park. So changed the oil, but only gives a few extra pounds, relief valve looks OK. Going to put old smokey back in, it can just about pull the skin off a rice pudding and fills the street with smoke on first start but it is reliable and confident that it will get my daughter to her prom. My late father often said to me if its not broken do not try to fix it, still convinced that I have a good engine but will have it done properly next time.

[welshrat]

Engine out this evening, 2 and a half hours, hoping to put old smokey back tomorrow. How do I change the title of this thread, thinking it shoud be Engine swap - there is no greater fool than an old fool, well you live and learn I guess.

[welshrat]

Original 1275 motor back in with larger bore exhaust and Hif 44. Oil pressure good and it is acually running better than it ever has, seem to have lost that flat spot while accelerating, espeacially up hill. I will change the oil and filter and hope for the best I think.

[bmcecosse]

Good thinking! 20W50 of course.......

[welshrat]

Well all the time I put into changing the motor was possibly worth it after all, yes I had to put the old one back in but what a difference the new carb and exhaust makes. Took the old girl to work yesterday (35 mile round trip) for a trail run, no problems and flew up the steep hills that used to be a struggle, I thought that I had gone a little too far with the 3.7 diff a while back but now thinking that it was all to do with the carb/exhaust. Anyway drove my daughter and her three friends to their prom tonight and again no worries on the power front, flew up some pretty serious Welsh valley hills, it is like driving a different car. Driving home alone I put my boot down a bit, not sure how quick I was going as not got around to fitting the new speedo that I hope will give a true reading (currently 25 on the clock = 30 mph), clock said 60, not sure of my actual speed but it was pretty quick and rather scary, not doing that again. Also I do not have the plumes of white smoke on first start anymore, not sure what thats about, I do not have any choke as not sorted the longer cable, however it starts first time everytime without any problems.

[bmcecosse]

Great success then !

[welshrat]

Well I am a happy chap, probably would have gone on for many years with the old set up, just using it on rare occasions because it seemed under powered and on its last legs, for the first time in thirty years I am feeling confident about taking it almost anywhere. I suddenly have a car that can keep up with and on a few occassions this evening fly past the modern motors, need to check out the miles per gallon next.

[bmcecosse]

To save me ploughing back through it all -exactly what is the difference to the engine set-up now?

[welshrat]

Hif 44 replaced original midget twin carb, 3 into 1 manifold that slots into an inch and three quarter exhaust system with two boxes replaces cast manifold and slightly shy of one inch original exhaust system.

[welshrat]

And inlet manifold from mg metro - the water heated chap.

[bmcecosse]

Tiny twins are hopeless - well done with that upgrade! your engine can BREATHE now !!