How can I tell the difference between a 3.4 and a 2.8 by looking at the engine while its in the Fiero if it has the Fiero intake and what not on it?

There is a big 'F' maybe 1.5" tall with white paint on it stamped into the block if it's a Camaro/firebird 3.4. If memory serves it's a few inches above the oil pan on the rear facing of the block. You should be able to see it by jacking up the car and looking from underneath.

I'm no pro though, someone else here probably knows more.

The harmonic balancer, maybe.

A 3.4 will have a raised boss on the "trunk" side of the block, for the crank sensor. It will have a threaded hole, for a bolt, and a small metal plug, where the sensor would fit in. (88 2.8s also have this boss, but all it has is the threaded hole for the bolt. The larger sensor hole is not drilled.)
It will also have a plug in the top surface of the block, just above the timing cover, where the cam sensor would go.
A 3.1 might also have these plugs, but I'm not sure.

As posted before, the large "F" cast in the side of the block will be a dead giveaway.

If you can see the block where the starter is bolted...
On a 2.8, the ear that sticks out will be flush to the top of the starter, the entire width of the ear.
The bottom edge of a 3.4's "ear" will be beveled at an angle, leaving a bit of a gap towards the outside end.

[This message has been edited by Raydar (edited 03-04-2015).]

Thanks, now I know what to look for.

The 3.4 block also has an embossed ribbing look on the sides for strength where the 2.8 is smooth

All these references are great , but I'm surprised after all these years that someone here with access to both engines hasn't done a thread with images showing the differences.

Great project for someone. Could be worth a few positive ratings!

There is a thread, I used it when buying mine.

IIRC the obvious indicator is the dipstick ends up in a difficult to reach location. Also, I think the handle changes from red to yellow.

[This message has been edited by thesameguy (edited 03-05-2015).]

I can vouch for the dipstick angle issue. It lays right on the recall weatherstrip.

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quote Originally posted by Patrick: All these references are great , but I'm surprised after all these years that someone here with access to both engines hasn't done a thread with images showing the differences. Great project for someone. Could be worth a few positive ratings!

Yeah, I'm supprised too,.......oh wait,... I allready did


3.4L pushrod Swap (lots of pics) by sardonyx247 page 13

quote Originally posted by sardonyx247: Yeah, I'm supprised too,.......oh wait,... I allready did 3.4L pushrod Swap (lots of pics) by sardonyx247 page 13

Nice pics, thanks.

From my contribution to Sardonxy's 3.4 thread when I built mine
(page 9)
//www.fiero.nl/forum/F...3/HTML/000026-9.html
My block before paint.
Note the "F" on the casting and all the reinforcing ribs that are not on a 2.8 block.
Also note the plug with the hex nut in the hole that would normally have the crankshaft sensor in it.

[This message has been edited by randye (edited 03-06-2015).]