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MG MGB Technical - new built.

hi .
just had an engine fully rebuilt rebored, ground crant, re profiled cam all new bearings, pistons, rings,block and head skimmed seats hardened..etc. what do you recommend procedure on first start up.
thanks in advance bob.
1970 bgt
Bob Taylor

After fireing up the engine and checking for leaks, the most important thing at this point is to bed in the cam and lifters. Running the engine for 20 minutes at 2,000 RPMs will allow enough oil to lubricate the cam to accomplish this. RAY
RAY

Bob, first of all disable the ignition, then spin the engine until you have good oil pressure. Enable the ignition again & fire away. Barrie E
Barrie Egerton

Bob

Know this will be somewhat controversial,but there are some of us that don't feel running at 2000 rpm for 20 to 30 minutes is the best way. It may bed in the lifters and cam, but not necessarily good for the rings.

Other posts recommend running the engine on a good back road where you can accelerate hard and brake hard. Do this for about 20 miles (accelerate/brake) and it will seat the rings nicely.

Make sure you have a very high level of ZDDP in your oil.
Bruce-C

I had good success with running the engine between 2000 and 2500 rpm for the first 20 mins to bed in the cam, varying it regularly. A slow idle in fact causes much greater stress on the cam "nose", whereas faster revs cause the tappet to almost launch over the nose, reducing the pressure on the most critical part of the cam. After about 20 mins, the cam lobe surfaces, and the tappet faces, are work hardened and will last a long time. At slow idle, it is possible to wear off the heat treated area on the tip of the cam lobe (ie nose), leading to premature failure. A great explanation of this can be found at http://www.pumaracing.co.uk/cam1.htm.
After bedding in the cam, I took the car out on the highway and put it in fourth gear, 2000 rpm, floored the pedal, got to 4000 rpm, then coasted back down to 2000 rpm, repeated several times. This seems to have resulted in a good ring seal, and my valves have stayed well in adjustment after the initial retorque.
I agree with the idea of turning the engine over beforehand to prime the oil pump. I left the spark plugs out so that the engine could spin faster on the starter, then reinstalled them and bedded in the cam.
The ZDDP is important for flat tappet engines, and is hard to find in regular oils, as it has pretty much been removed from modern oils. I believe redline makes oils suitable for MGB engines and the like. I have used the diesel oils up till the last oil change, but apparently they have recently become much lower in ZDDP, so I guess I'll have to order some Redline myself soon before the snow melts and its time to get her on the road again.
Erick Vesterback

Also should mention - do not be tempted to use synthetic oils in your newly rebuilt engine. They are actually too good for this process. Because they reduce friction so effectively, the engine may not run in, which could lead to permanent problems with oil consumption due to rings not seating properly. Use non synthetic oils that are high in ZDDP. The unfortunate thing is that the oil manufacturers do not list the amount of ZDDP on the bottle, so its hard to know which oil to go with. Also, the person behind the counter likely won't know what you're talking about if you mention ZDDP. There are a number of threads on this board which talk about oils and ZDDP, which may be of help to decide which oil to go with.
If you want to use synthetic oils, wait until there are 2 or 3 thousand miles on the engine before doing so.
Erick Vesterback

Go to a General Motors dealer and purchase a bottle of E.O.S. (engine oil supplement) use the whole bottle in the start-up oil.
GM uses it in their rebuilt motors.It will supplay all ZPPD you need.
Sandy
conrad sanders

This thread was discussed between 01/03/2009 and 02/03/2009

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