2.8 to 3.1 Cam question

[TiredGXP]

I'm planning a 2.8 to 3.1 swap in a Fiero.

The plan is to use the block and crank from a 1990 Lumina sedan (appears to be a gen II 3.1 with canted valve aluminum heads) so I can run a DIS ignition and knock sensor.

This swap will retain the 2.8's top end, just to retain the stock Fiero look.

As you can tell, this is not a high HP swap, With porting of the intake, heads and exhaust I might get 165HP out of this, which is fine as this will be my son's daily driver. (New driver, so lower power to keep him out of too much trouble.)

QUESTIONS:
Do these engines use cams with the same size journals?

The specs posted elsewhere on this forum indicate that the 3.1 used the following size journals:
Journals 1 & 4 51.03-51.08
Journals 2 & 3 50.77-50.83

and the 2.8 used these:
Journals 1,2,3 & 4 47.44-47.49

I've already purchased a Crane 2030 cam, Crane's website showed the same cams for both the 1985 2.8 and the 1990 3.1, so WTF is up with the different journal sizes? With more than 3mm difference in the specs posted here, does that mean that the 3.1 block has been machined differently?

I haven't finished pulling out the 3.1 yet, so haven't had a chance to measure anything. I just want to ensure that I get the correct cam bearings for this cam, and that they actually fit the block.

[Superdave]

all gen1, 2 and 3 60v6's use the same size cam bearings.


Using the Iron heads on a FWD engine will result in around 7.2:1 compression.. you'll make like 90 HP with it that way.. lol

I think you'd be much better off to leave the aluminium heads on it and use the thinner headgaskets made for the iron heads. That should put it up to 9.4:1.

with that cam in a full gen2 3.1 with a little P&P you'll probably get to 165 HP

[TiredGXP]

Thaks for the response.

Well, I figured that a rebore will probably be required, so I was planning on installing the 3.1 iron head pistons to retain the compression ratio.

I've already completed the P&P on the HO iron heads, and have complete new valvetrain components (Springs, 1.6 rockers, valves, seals, pushrods) for those heads, so I'm pretty well committed to retaining the 2.8's top end.