455 Olds in 84 Cutlass - motor mounts?

[Mallard Road Garage]

Hello all
I just joined so here goes my first question. Can I use the small block 350 olds motor mounts to install a 455 Olds in my G-body Cutlass? If not, what motor mounts are required. Appreciate your time.

 

[TURNA]

yep u can use just about everything from the 350

 

[Mallard Road Garage]

Awesome, thanks so much for your timely reply. Nice Cars!!

 

[TURNA]

I believe you can use all the pulleys too. You will just need belts about an inch longer

 

[olds307 and 403]

If his car is A/C, he will have to lengthen the A/C compressor brackets. A factory non A/C set up will bolt right on with longer belts. The passenger side, non A/C alternator bracket has two sets of holes. There may be interference with the heater box and the valves cover. All 73 to 90 Olds V8 motor mounts are the same except the fwd ones.

 

[Kennybill]

What intake manifold are you going to use?

 

[1bad79]

I have a 455 in my 79 cutlass it was a 260 car so I just ordered up stock replacements and bolted it in

 

[olds307 and 403]

Personally I would keep the Olds 350, add compression and cam. Remember a stock bottom end 455 does not like RPM, I would put a rev limiter on it and stay around 4500 RPM max.

 

[fleming442]

I would put a rev limiter on it and stay around 4500 RPM max.

That may be a tad excessive. Built correctly, they'll go to 5500-6000 no problem. Mine is intake/cam limited to about 5800. I wouldn't hesitate to spin it higher with the light rotating assembly if it breathed better.

 

[olds307 and 403]

That may be a tad excessive. Built correctly, they'll go to 5500-6000 no problem. Mine is intake/cam limited to about 5800. I wouldn't hesitate to spin it higher with the light rotating assembly if it breathed better.

Note how I said stock bottom end 455, I almost guarantee that is what he is getting or with heavy Speedpro pistons, no help at all, maybe even worse. You know how many 455's I have seen for sale with a knocking bottom end, quite a few. Add aftermarket rods and much lighter pistons and it no doubt helps a lot. The 350 is very reliable and I have always ran them, so it is just my opinion.