What size engine is in my truck?

[Thatguywithaneye]

I recently inherited a 1972 GMC Sierra Grande from my grandpa. I’m trying to get started on the truck, but I can’t figure out what size the engine is. I know that it’s a V8, but they released 3 models that year: the legendary 350, the 307, and 402. The truck is the 4x2 3/4 ton.

I am new to this kind of stuff and I’m just learning so take it easy on me please!

Thanks for any help!

[Killer Bee]

howdy, welcome aboard!

spid decal in the glove box if in tact should list it..

easy way to tell sbc from bbc is the rocker covers, good luck!

sbc [283, 305, 307, 327, 350, 400]



bbc [396, 402, 427, 454]

[Alex V.]

Options sheet in the glove box, possibly an emissions sticker on the air cleaner? stating engine displacement (assuming it's original to the truck), or the stamped codes on the block at the front of the passenger-side head can be decoded.

[panhead59]

If you list the #'s on the front of the block by water pump and #'s on back of block by distributor, I can tell you exactly what you have. You could also find the info online if you have those #'s handy.

[weq92f]

Well I'm hoping it's either the 350 or the BB.

-klb

[GASoline71]

I don't think 3/4 tons came with a 307.

Gary

[Thatguywithaneye]

Originally Posted by Alex V.

Options sheet in the glove box, possibly an emissions sticker on the air cleaner? stating engine displacement (assuming it's original to the truck), or the stamped codes on the block at the front of the passenger-side head can be decoded.

It is the 350! I did find it on the options sheet. Thanks for all your help. Wow this is such a big community on here. I will definitely be asking lots of questions.

[Custom 68]

Nice options.

[crazyjeenyus]

Looks like your Grandpa wasn't shy on the options. Unless you know for sure, there is always the possibility that the engine is not the factory engine that came with the truck.

In this case, the easiest way to id the block is to locate the engine VIN pad (front passenger side of the block) located at the top of the deck where the cylinder head spends it time.

I'm sure there are several good sites that provide info on these numbers/letters, but the one I have found most abundant with info is:

http://www.nastyz28.com/chevy-engine-code-stampings.php

The numbers on the block ID pad will help you identify where the engine was installed in the vehicle, what type of vehicle it is (C20 pickup) and there will be a series of 2 or 3 digit letters known as the suffix code. Those are the letters you'll be looking up in the above link.

Hopefully this helps. The info I have found has been pretty accurate with the exception of my '67 283 block that is original to my truck. Running the casting number it comes up as a '67 283 with some notes saying that it was replaced with the 307 in '68. But when I look up the suffix code, the resources identify it as a 307. Deciding factor was the good old fashion visual check which was the PCV valve at the back of the lifter gallery, and the tall oil filler tube at the front of the intake manifold (pretty sure 307's didn't have these).

Anyways, check out that website for further confirmation on your engine block's history. And good luck on your truck.

[jocko]

First time I’ve seen “willow green” actually types on a SPID. Welcome, very nice truck you have there, enjoy and ask all the questions you want!

[Already Gone]

Welcome to the site from a fellow Canuck. This is a great place and you will get all the respectful help and advice ( and sometimes too much advice ) you need for your truck. You have a family heirloom and that is special. One thing about this site is we LOVE pictures so please when you get a chance post up some pictures of the truck.