I am putting together my first engine and I was planning on using Plastiguage to check my bearing clearances. A firend told me that Plastiguage is unreliable and I need to have it done by a professional. The crank and bearings are new, so I did not think it would be a problem. Is plastiguage sufficient to reliably check bearing clearances?

Plastigauge isn't the greatest, but hundreds of thousands of engines have been rebuilt with it. Certainly it's better than not checking clearances at all.

If you were to take it to a shop they would probably use plastigage anyways unless your paying a lot of money for machine work. I would invest in a nice set of inside outside micrometers as well. I shown by my engine builder that is you put a single sheet piece of paper in between the crank mains and it locks the crank then your clearances are close enough. Has always worked in the past! just my

I built my motor with plastigauge. The green stuff... It should show .0025" or thereabouts. Its a good sanity check. If everythings new, you shouldn't even need it, but to confirm you're in the ballpark, it'll do the job.
If/when you decide to build more motors, get yourself a micrometer set, and a bore gauge.

plasti gage is a good way of getting around doing it the right way. like was said there's a very good chance you won't have a problem at all and if you do plasti gage ought to catch it. on the other hand you're asking it to catch the differance in very small variations in clearance.