Some of us here have completed the 4.9L swap but even fewer have used the 4.5L manifold. While the pics show the smaller C130 alternator mounting adaptation on my 4.9L engine it might offer some ideas on how to make the 4.5L alternator bracket fit. The swap may be dated it still offers, low swap cost, low engine weight, plenty of torque, a relatively easy installation and great hwy mileage. You will need to tweak the program to work with this manifold that uses a different throttle body and TPS. You might ask Raydar about that as he is the one that pointed this out.

[This message has been edited by Dennis LaGrua (edited 06-19-2021).]

I don't remember my 4.9 bracket looking like that, but I believe I used mine for the Allante intake. I *did* use the 4.9 alternator. It makes it very crowded on top of that intake.
I had to remove a substantial portion of the back end of the bracket, to make it fit. I believe I used a cutoff wheel to do the deed.
Everything that lined up before, still lines up. (Pulleys, brackets, etc.)

On second thought... Maybe my bracket WAS like yours. I figured there would be one for sale on eBay, to compare. The two that I found look exactly like yours. And there was nothing remarkable about mine that should have made it any different.

Don't know if this will be useful or not...


Edit - Now I'm going to have to go and look. (And yeah... Dennis' installation is much prettier than mine. (Although I didn't do the initial install, I did the Allante stuff and the 5 speed.)

[This message has been edited by Raydar (edited 06-19-2021).]

quote Originally posted by Raydar: I don't remember my 4.9 bracket looking like that, but I believe I used mine for the Allante intake. I *did* use the 4.9 alternator. It makes it very crowded on top of that intake. Edit - Now I'm going to have to go and look. (And yeah... Dennis' installation is much prettier than mine. (Although I didn't do the initial install, I did the Allante stuff and the 5 speed.)

Very good point. My 4.9L alternator bracket did not look like that either. Maybe it was for an earlier 4.1L/4.5L engine. Actually the real reason of using the smaller GM C130 alternator was gaining deck clearance that I really didn't need as the car is a notchback. Regardless I do like the more compact look but adapting that to the 4.9L (its an 87 Grand Am unit) required making some very precise spacers, and a small straight bracket piece to achieve proper belt alignment. As for being a pretty swap; IMO the 4.9L swap is a difficult engine to achieve that look but if you move the MAP sensor to the front side, remove the EGR valve and put a block off plate there (for off road use only of course) it takes away a bit of the cluttered look. Good luck with the swap. Its miles better than the 2.8L.

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" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 06-19-2021).]

That looks very familiar.
I'll have to go and look. I'm not sure that my alternator is supported on the back side, at all. But it hasn't caused any issues. At least not so far.
If I don't get covered up with honey-do's, I'll try to get some pics today.

Edit... I remember what I did now. I ran a flat strap from the bolt nearest the shock tower to a boss on the lower intake. (You can see it beneath the corrugated loom.)
This is not regular pipe strapping. It's fairly thick. Pretty much "bar stock" except that it's drilled. No idea where it came from.

[This message has been edited by Raydar (edited 06-20-2021).]