Some questions in engine rebuilding....

[nimblestix]

I think meant 1/2" my mistake...

sent from a galaxy far, far away

[Skym]

Hi guys. I have some questions in my mind about engine rebuilding.

1. I know tomei poncam supposed to be drop-in application that require you to re-shim to get the required clearance but that's it. But I have also read many articles saying if you put in new camshaft you also need to use new lifters and at first start up the engine must rev to 2000rpm for 20 mins to mate-in the surface between the lifter and cam lobe. Which is true?

2. Let say I have a rebuilt engine (new camshaft new lifter) installed with zero km and zero start up, and let say I should do the 2000rpm 20mins to break in camshaft, does that mean I must not try to start the engine and must leave it to the hands of tuner to get all setting right and they do the break in? How can I know if I do my job right? Or I can't know until the tuner tries to start it?

3. Let say it is true that I need to break in the camshaft using the method described above, isn't that contradictory to what you should do to break in the piston-rings? Like you should move your revs ups and downs for piston ring to get more lube to mate with the cross-hatch.

4. Is a regrounded crankshaft any good?

Thanks for the opinions.

If using a new camshaft, best to bed in each lobe with new lifters. If using old camshaft's, can get away with the old lifters, as they are already bed in with each lobe. Changing valve springs is a good idea as well with new camshaft's, as affect's break in, clearancing (springs sag over time). Also Tomei mention to use additional shims with their new valve springs, to bring the valve seat pressure up to factory specs.

To properly break in a engine is a expensive process if done properly.

I noticed some do it this way -

1.) Using break in oil, new oil filter, set up injectors, AFM's, maps, etc before starting engine, start engine and break camshaft's in, set idle, adjust startup, etc.

2.) Send to dyno and break in on chassis dyno that has a break in program

3.) Change oil + filter, tune to 5000rpm

4.) Break in engine on road for 2000km, change oil + filter and retune engine

5.) Break in for a further 3000km, then change to normal oil + new oil filter.

Some say breaking engine in for longer before retuning helps to produce more hp.

Engine when properly broken in is usually loaded onto a engine dyno, initial break in for a few hours, including breaking in the camshaft's. This is a commonly used procedure with stock R35 GTR engine (quality control), supercar (quality control), race car engines. Even Nismo initially run in the engines they build on a engine dyno. Then chassis dyno is used to check tune and finally a road or track tune.

Nissan mention the road break in procedure in their manuals (for R35 GTR, etc), so best to follow what they recommend as far as rpm, etc goes.