I just recently bought a 80 model cutlass from a mechanic shop that had been sitting for some years.The engine was changed but I want to know how to determine the size of the engine.

 

The first question is, is it a V6 or V8? These cars were available with either Olds V8 motors or Chevy V8 motors (in addition to the Buick V6), and if it's been changed it could be almost anything. An Olds V8 will have an oil fill tube at the front of the engine above the water pump. A Chevy will usually have the oil fill cap on one of the valve covers. If it is an Olds motor, there is a casting number on the little shelf next to the oil fill tube. Post that number here and we can tell you what the block is.

 

these numbers came off the top of the block 4790 GM 5.0LG.Thanks Gene

 

Gene,

Welcome to our site. 5 liter engine is a V8.

 

Yes I know it is a V8,how do I determine if it is a 305,307,350 etc.

 

Its a 305. use the internet. Type in liters to cubic inche calculations. Several pop up

 

I think that would mean it is a chevy engine.

 

Dont some of the 307s have those numbers? Where is the oil fill at, on the valve cover or above the waterpump?

 

Since there are a little more than 6 cubic inches in a tenth of a liter, displacements from 302 to 307 cu in round off to 5.0 liters. Heck, the LS1 version of the Chevy 5.7 liter engine is actually 345 cu in, not 350.

As for this particular engine, the casting numbers sound like an Olds 307.