My 77 Electra has a 403 Olds engine. Runs great but I'm kicking around the idea of replacing it some day with a 455 Buick engine. Has anyone done this conversion? I once dropped a 455 Olds into an 85 LeSabre that originally had a 307 Olds with no big problems. Would it be that easy with the Buick engine?

sure,it'd be as easy as dropping one into an 85.
i've done several 81-85 455 swaps into 80-85 lesabres,be sure to soup it up,
nothing is more fun than the look of a honda chivvy or ford guy when a 4 door buick leaves him in the dust!! good luck!!
jeff wecker
1984 le sabre 4 door(500 hp 430)

Contact "Electra" Jim at electrajim@hotmail.com Helped him do just this back in...oh...the mid to late 80's. The car started out running 14's with his first motor. Now runs low 12's with his 2nd motor. Has worked through several different trannies, rear ends, carbs, cams, intakes...has it all figured out. Drop him a line and he'll help you out. Tell him Scott sent you.

I did a simular swap, '78 LeSabre with buick 350 to
a '70 455 Olds big block.
Hardest part was the exhaust. The motor mounts from
the donor car fit the LeSabre prefectly.

Add a 400 th trans for better performance, not the 350 th, you will burn up gears and clutches.

The TH350 can be built to stand the HP, and it is lighter. But a stock TH400 will hold up better...if $$ for rebuilding the TH350 after you kill it isn't in the budget.

I concur with Adam. If the 4-cyl-designed THM200 can live behind a high-torque Buick 3.8L Turbo, then a TMM350 can live behind a Buick 455, I suspect, if built properly.

From what I've read, the strongest THM350 (most cluthes in the clutch packs) was for the 1981 Corvette and 1981 Camaro Z-28 trans. The THM350 will take about 15 horsepower LESS to run than a similar THM400, if that matters. KEY THING on any of those transmissions is to have a case with the correct bolt pattern on it.

Of course, there's also the THM700 with the deep low gear (which the drag racers seem to love) and overdrive on the top side. Might need a 3.73 rear axle ratio to be able to really use the OD to its advantage, though.

Even with the THM400, there were some internal "guts" variations depending upon which engine it was behind and what chassis it was in. Doing one with "Switch Pitch" might be neat, too!

Enjoy!
NTX5467