1969 chevelle

[joker1s]

How do you find out what the original motor size is supposed to be?

[taillight]

It is in the VIN code.

[highlandlake]

Originally Posted by taillight

It is in the VIN code.

Sometimes but not always..........a '65 for example will indicate in the VIN that a V8 was assembled with the car. But there were four sizes available. Could have been a 283, one of two different HP-rated 327's or a 396.
Dealer invoices, or build sheets are more helpful in these cases.
Other indicators would be the original motor mount holes, fuel line size, springs & suspension, brake disc or drum size, and sometimes the emblem holes or gauges or trim inside the car.
My

[shaneland]

What size motor is in your car?

It would be on the build sheet.
The build sheet can be located under the rear seat, front seat, gastank or inside one of the back side panels...

post a link to a pic of your car...