how do i find what size of engine i have. i have the block number?

Question

i have a 67 pontiac grand prix. i have always believed it had a 400 big block. but i have heard from others that 428 was the only engine size available for that year and model

Answer 1

The 428 engine is rather easy to identify. There is a rather large "428" cast right into the side of the block. Really easy to see if you have the engine out, not so easy if the exhaust manifolds are in place.

The engine code is stamped on a pad on the RF of the engine block. Get the code and check any number of sources (free on the web) to see what engine you have. Caution: Pontiac reused engine codes over and over. You need to know what year engine you have. If it's an original that won't be a problem. But if it's been replaced you need the date code, which is stamped near the distributor hole, IIRC (it's been a while). Again, there are lots of sites on the web that will help you for free.

BTW, '67 GP - nice ride! I have a 428 out of a '68 I'm saving for a special project GTO...

Answer 2

You'll need the codes stamped into the front pass side of the block, the head casting numbers (on center exhaust port), the date code by the distributor hole, and the block casting number by the bellhousing for a positive ID. GPs had 400 2bbls stock, but could be special ordered with a 4bbl or the 428 high po motor. All pontiac engines are the same size externally, so its hard to tell them apart without running the codes. Also, most of these cars have swapped engines by now, so running the codes is the only sure way to know.

BTW, a Pontiac engine is totally different from a chevy, olds, buick, etc.

good sites:

www.pontiacstreetperformance.com
www.performanceyears.com

Answer 3

67 was the year they changed motor sizes..400 and 428 were only available choices.-some had label in engine compartment that showed size and belt drives-depending on previous owners-you can input vin, block, or head number on jasper.com-they have a link on their page that will show vehicle options for powertrain.

Answer 4

Here's a list of Pontiac block casting numbers from 1955 through 1979. Link below.

Answer 5

It's one of two motors. A 389 or a 421 cubic inch engine. To my knowledge the 400's were only found in Firebirds.

Answer 6

I believe that GM has always stamped the engine displacement in liters on the block itself. It's normally on the back of the engine somewhere. If the car is original you could also run the VIN number and this would tell you what kind of engine the car has.