Houston_t

So here's the deal, i just purchased a 71 Cutlass Supreme convertible with a 350 Olds in it and 350 trans, the engine is stock and has 70,000 ish mile on it and actually runs good. Im looking to step up the performance slightly without pulling the engine and doing a complete rebuild, if i pull the engine out something else is going in either a 455 or LS swap. What parts would you guys be looking at ? Im not looking for a drag car just something faster off the line and a bit more passing power on the highway. Also what would a shift kit and torque converter do for me performance wise ?

Thanks

svnt442

3.42 gear and a 200 4R trans. That will be you're best bang for the buck, hands down.
If you're going into the trans already, might as well upgrade.

Cutlass Fan

2 bll or 4? Single or dual exhaust? If not the 4bll or dual exhaust upgrading to those will help. A higher stall converter will help off line but won't help passing. I agree with svnt442 swap in a 3.42 and 200r4.

sschevellecutlass_Bob

how about new intake and carb.... or a new EFI?

Houston_t

It has a 4 barrel carb and single exhaust, i was already thinking of doing the holley sniper EFI, did the FiTech on my chevelle and liked it but figured that would be more of a reliability thing and prob wont add more in the performance department. If i go 2004R do i need to find a grand national trans or will ant 200 work ?

Koda

Going overdrive and a lower geared rear differential will help off the line. It will not help on the highway because the final gear ratio is about the same. Exhaust will help, and putting a different cam and lifters in will help. I believe that any 200 4r trans will work but will need some upgrading.

That will get you *some* power. Some people need serious "being obnoxious" power and will put a 455 in. That is a respectable thing to, especially since yours isn't a 442 or anything rare. We have a few people who put LS engines in their Cutlasses, but we generally keep them in the "non-Olds powered" gulag as the heretics they are.

olds 307 and 403

Any 2004R trans with a few upgrades will work. Along with 3.42 gears, you will gain performance and mileage. Add duals and maybe Thornton's new stainless shorty headers, it will sound better and add performance, it did from the factory.

joe_padavano

You might want to do the math. The 200-4R has a 2.74 first gear ratio as compared to the 2.52 first gear in the TH350. That alone will improve off-the-line acceleration. Even if the car has a 2.78:1 rear, the trans change alone would be like changing to 3.00:1 rear gears. Now if you change to 3.42:1 gears AND change to the 200-4R, first gear will be equivalent to 3.73:1 gears with the TH350. Additionally, the 0.68 overdrive in the 200-4R knocks those 3.42s down to an equivalent of 2.33:1 on the highway. What's not to like?

sschevellecutlass_Bob

I would talk to Bow Tie Automotive about the 200R4 to see if they make an Olds version......with a 350 and moderate torque you should be good from what I have heard. There are some parts that you may want to beef up for peace of mind.

joe_padavano

You'll be hard-pressed to find a 200-4R case that ISN'T an "Olds version". Except for the early cases that are BOP-only, all 200-4R cases are unisex.



FYI, it may be 700R4, but it's 200-4R according to GM.

sschevellecutlass_Bob

Thanks and roger that Joe.... I usually dork that 200 700 4R R4 up.

joe_padavano

Yeah, I never understood why they were different. I mean, geeze, pick one and stick with it.

Koda

I think I said that. Big change off the line, not much on the highway. (I'm assuming the car has a 2.56 now with how he is not impressed with power).

Now, kicking it on the highway, the 200-4r and 3.42s drop you to 3.42 in third. Can a 200-4r drop to 2nd at 60mph? 5.37 there. The th350 dropping a 2.56 into second will net 3.89. This is why passing gear in non-overdrive turbohydramatics is strong power.

joe_padavano

Actually, base axle with the 4bbl 350 was 2.73:1. With the 2bbl it was 2.56. In either case I'd think that an equivalent 2.33 ratio would be a noticeable change on the highway.

Koda

Oh. Ok. I see your point.

What do people like on final ratio? I have another A body with a 350 and a 2.73 rear end and it sits at 2500 at 70. I like how it has usable power without downshifting.

olds 307 and 403

I calculate more like 2750 RPM at 70 mph, unless you have very tall tires or a lock up converter. A 2004R with the converter locked up and 3.42 gears, 2050 RPM at 70 mph.