The topic of engine cover hinges seems to come up from time to time. There seems to be some discrepancies about which parts were used. Maybe it's a regional thing? I don't know. I've posted pics in the not too distant past. Here are some pics of the parts I have.
This is a comparison of the '77 hinge (left) next to another early ('74 - 1300/4spd) hinge (right). As you can see...the hinge on the '77 is taller. (I don't know why Fiat made the change, but if you do, I would like to learn about it.)
View attachment 48830
But because the hinge is raised on a '77, the engine cover itself, and the plastic side grills are also changed to accommodate this raised position.
Here is a pic of the passenger's side plastic grill. It has a plastic riser (circled in red) attached to bring the rubber gasket to the same height as the now raised engine cover (it would look a little funky without this piece - the gasket would droop on both ends).
View attachment 48831
The sides of the engine cover are also taller on a '77, again to accommodate the raised position of the engine cover - they fit tightly to the plastic side grills. If the sides of the engine cover were not longer, there would be a gap between the bottom of the engine cover and the top inside edge of the plastic grills.
This is a pic of the early engine cover side. It's just over 12mm high.
View attachment 48832
Here is a pic of the '77 engine cover side. It's about 30.5mm high.
View attachment 48833
The another thing that's different about the '77 engine cover it it's latch "tang", it's also taller.
Here is a pic of a non-'77 early engine cover latch tang. It's a bit over 34mm tall.
View attachment 48835
Here a pic of the '77 engine cover latch tang on the right. It's about 79.5mm tall. (The late engine cover is on the left.)
View attachment 48836
The other thing that's different about a '77 engine cover is the plastic filler strip that's screwed onto the rear, to fill the gap that results when the engine cover is raised (sorry I don't have a good pic, all mine are kinda crappy and I need a good one, anyone have one for sale or trade???)
The engine cover for the later models (1500/5spds) is a completely different animal. While the hinges for the late engine covers are similar to the '77 hinges they are beefed up. Here the late hinge is on the left, a '77 on the right.
View attachment 48839View attachment 48840
The late engine cover has the tallest latch tang, at a bit over 87mm tall. Here are a couple pics, the late cover is on the left. The late engine cover is the "tallest" engine cover, and, it also has a plastic filler strip at the rear.
View attachment 48841View attachment 48842
The late engine cover will fit on an early car if you want to use it. You have to make a couple of adaptor plates to fit the later plastic filler bits that replace the earlier plastic side grills, but they are easy to fab up. It will require a bit more to adapt the late engine cover "prop spring" device to the earlier car (nut-serts will help), or you can just use a stick
to hold it open.
I've never attempted to put an early cover on a late car even though I prefer the look of the early cover. I would image that it could be done. (I wonder if the '77 engine cover would clear the FI intake manifold?)
Bottom line. The '77 engine cover is raised, and will give you more clearance to the top of the engine. (At least the '77 engine covers I have.)
But, to use the '77 engine cover without gaps you'll need: the engine cover, the hinges, the plastic side grill add-ons, and...the plastic filler strip at the rear of the engine cover (and you'll have to raise the rubber bumpers a bit too - not sure if those rubber bumpers were longer on the '77 or not?). You can not simply use the '77 hinges - or the late model hinges - without making accommodations for the raised position of the engine cover.