Tips on better performance/rodding a 300 in^3 engine with 2 spd

[BuickNut]

Any suggestions for a '64 Skylark with a 300 and 2 speed - how to turn into a nice performer but still everyday driver ?

Thanks.

[Guest brh]

I've got a 65 300 and its got plenty of get up and go! Have you got the 2barrel? Buick had 2 versions of this engine in 64 and 65. Mine is the high performance with 11 to 1 piston ratio, 4 barrel carb and stock posi rear end. The only thing I did was put duals on it to help it breathe better. Other than that I have no complaints.

[YellowLark]

Try the Performance section of this site. Use the Search function with "300". Many 300 owners have shared performance ideas on various sites.

[NTX5467]

Getting more power from the engine is one thing, but getting it through the 2 speed automatic is another.

One advantage of the Chevy PowerGlide (which I suspect is also related to the Buick 2 speed automatic) is that it takes less power to run it than a Turbo 350 and especially a Turbo 400 automatic. Seems like the PG takes 15 or 20 horsepower whereas the T350 takes 30 and the T400 takes 40?

Seems like there were some Switch Pitch versions of this trans too, just as there were for the Turbo 400. If there are, adding that would add some needed torque multiplication to the standing start performance, possibly getting closer to the torque multiplication of the Turbo 350 in the process. Adding a fixed pitch converter of a higher stall speed might not be advisable, though, especially for general street driving.

As with other GM automatics, firming up the shifts might be helpful too. In that same "heavier duty" orientation, could it be that similar transmissions for LeSabres had stouter clutch packs and bands?

Just some thoughts . . .

NTX5467

[Guest John Chapman]

NTX....

Some points to ponder:

Other than being a two speed automatic, the ST300 and the PowerGlide have <span style="font-style: italic">nothing</span> in common... not so much as a casting or gear...

The ST300 was used in various forms on the BOP cars. The six cylinder Tempest used it with an air cooled converter without switch pitch as the Tempest-Torque and the six cylinder F85/Cutlass as an aircooled fixed-pitch JetAway. The intermediate chassis V8 Olds (Jetstar-B Body and the A bodies used the trans cooled switch pitch as the JetAway. All the Buick ST 300 transmissions were switch pitch, regardless of application.

For performance upgrades to replace the ST 300, the 200R4 is a near bolt-in, requiring only that the tranmission support crossmember be moved back... or replaced with an aftermarket specialty crossmember fabricated for this purpose. With the 200R4, you get four speeds, with the top one being 0.67 OD. For all-round performance improvements, this would be the transmission of choice in my opinion. The TH350 and TH400 offer some advantages in handling brute power but lack the OD.

With the 0.67 OD, you can go to a 3.55 rear and have an effective cruise ratio of 2.38. Add a posi unit and you could have some real snazzy off the line punch without the engine screaming at 70 MPH on the freeway.

Cheers,

John

[BuickNut]

Thanks for the help - I'm doing some perusing for my dad and/or myself, and have come across some 300 with 2 spds, and was wonding if they were doomed to a life of boredom off the line. Looks like I can consider those cars now, without considering doing the 'ol 455 swap !

[NTX5467]

Valid points, John. The main power consumption issues are related to internal rotating mass and not specifically to Chevy or Buick transmissions. Therefore, I suspect the ST300 would take similar or less power to run than the THM350.

I also suspect one reason the Buick Turbo cars used the T200R-4 instead of the stronger T700R-4 had to do with the power consumption issue as we all know the T200 architecture is not specifically about torque capacity but lighter weight (considering that it was originally used in the lower horsepower engines when it was introduced). The Turbo cars also used the somewhat troublesome PowerMaster brake booster that uses an electric pump to charge the power assist accumulator--again probably in the interest of getting the most power to the pavement.

There is now an OD version of the electronic T400, the 4L80E. At one time, GM Performance Parts had a controller listed for it as a stand alone situation as the diesel versions (non-electronic pump models) had a separate controller for that trans. It is strong but is also big and heavy. I suspect a strengthened T700 would make a better choice for a higher powered street rod or modified vehicle.

As with the PowerGlide, the drag race guys have proven that with the correct torque converter, you can work wonders. Everyone likes that push in the seat upon initial takeoff, but if the tires have more than about 10% slippage on takeoff, anything else just goes up in smoke. Therfore, I suspect a properly set up ST300 w/SwitchPitch would get real close to what some of the other 3 speed automatics might offer in performance. In daily driving, it might be close enough to not be worth the time and expense to swap transmissions, but that just depends on what your ultimate uses might be too. As for the engine, leaving it biased more toward low and mid-range torque in cam and carb (basically stock) would be best, but to also let it breathe with a good high flow and quiet exhaust system to compliment the higher rpm capabilities which might be there. Basicaly a torque motor that will wind out and not get winded .

Enjoy!

NTX5467