2-Speed Powerglide - upgrade to 327 [Archive] - Team Camaro Tech

: 2-Speed Powerglide - upgrade to 327

Feb 24th, 03, 11:17 AM
'Maro Techs,

I am upgrading my 67 Camaro convertible from a straight 6 to a 327 engine. I currently have a 2-speed powerglide and I understand that the 327 works with a 2-speed powerglide. I have a 10 bolt rear.

My question is this - how much more power will I realize if I upgrade to a better transmission such as the TH400?? I am not racing this car - this car is being restored for enjoyment. Is it really worth the effort and cost to upgrade the transmission or just enjoy the extra power from the 327 - your thoughts please!!


67 Plum
Feb 24th, 03, 11:29 AM
The glide will work but a TH350 would be better. I went from, a glide to a 350 in my 67 & its like a different car. The 350 is a bolt in the TH400 needs shorter drive shaft & a different crossmember. Also you might want to ungrade to an Eaton posi.

Feb 24th, 03, 11:32 AM

I think I understand what you're getting at. You won't see any power difference with a different tranny. You're going to see a major change going from a 6 cyl. to 327 though!

The Powerglide is fine for a daily driver that's not going to be raced. It is only a 2 speed though as you said, so cruising along on the expressway is really gonna wind that 327 up at 70mph! The only reason I'd change to a TH350 or 400 is for the third gear. That's about it. I think a TH400 is overkill but if you can trade the PG for one or sell the PG and get a rebuilt TH350 or TH400, I'd definitely go for it.

Feb 24th, 03, 12:11 PM

I think you answered my question - I guess I was really debating with keeeping the PG but it still runs fine and since I'm not racing this car the extra gears shouldn't make a noticeable difference - guess it hurts nothing to hook up the powerglide and then change trannys later if I need to - thanks for your thoughts!!


67 Plum
Feb 24th, 03, 12:15 PM
The RPM at 70 will be the same with a glide 350 or 400 all have 1:1 high gear. The glide 1.82 low & 1:1 high. The 350 has a 2.54 low 1.54 secound & 1:1 drive. The 400 is 2.45 , 1.45 1:1 drive. The driveability ia greater with a 3 speed tranny because of the ratios. The only way to drop cruise Rpm is an overdrive a TH200 is basically a bolt in only requires a TH400 crossmember.

Feb 24th, 03, 12:22 PM
327 with a powerglide was a standard combo!

Moving from a powerglide to a TH350 or TH400 will COST you power! A PG has the least rotating mass so uses the least power to move the gears. TH400 uses the most due to the heavy gears. But the extra low gear will help acceleration.

As 67 plum said, either trans final gear is 1.1, so 70mph is the same RPM. You need to look at the rear gear.

A dog 2.73 rear gear is tough with a PG, better with a TH350. I upgraded my 327/PG car to a 3.55 posi rear from 3.08 open. Waiting for spring to see how well it does.


67 Plum
Feb 24th, 03, 12:29 PM
The 350 is still better low gear 2.54 x 3.08=7.823 a glide with 1.82 x 3.55=6.461 these are final drive ratois. The 350 with a 3.08 will launch better & turn less Rpms at speed than the 3.55 gear & glide. The 1.82 ratio is a 6 cylinder glide a v8 glide is 1.76 that times 3.55 is 6.248 even less ratio.

Feb 24th, 03, 03:11 PM
Swapping to the TH350 will make the car more fun to drive as that lower first gear will give better torque multiplication for better accelleration. I swapped from a PG to a TH350 and it "feels like" picking up 50 horses. Of course this isn't really the case.

Feb 24th, 03, 04:08 PM
I too recommend the TH350. While you aren't actually gaining horsepower, you ARE actually increasing torque in first gear through multiplication, and it is very real and noticeable. If you aren't after improved accelleration, then don't bother. I had a 'glide in my 200HP hp 307 '69 convert with 3.08's, and it didn't have enough power to pull a fat girl off of a tricycle. The lower first gear will feel like a supercharger!

While true that it takes less HP to run a glide as compared to a t350, that is essentially a non-issue in a street car. Drag racers who are making metric tons of torque in the first place don't need the torque multiplication in low gear as they offset any deficiencies with rear end gears and cubic inches/dollars. You will see Powerglides in very fast cars and very slow cars... but not too many in between. (I realize there are exceptions)

Feb 24th, 03, 04:41 PM
I stand corrected when it comes to final drive at cruise speeds. My bad... and I agree with BPOS.

He's going from a 6 cylinder to a V8! The transmission is a moot point. He's asking about power. It'll be a whole new world when that 327 is in the car. For his needs, unless he wants to change the tranny during the engine swap, the PG will suit him just fine.
Kyle, you can easily go from that PG to any number of transmissions at a later date if it doesn't suit you. And as we all know, you WILL be playing around with the driveline again sooner or later! ;) We're never satisfied, are we?
If you're also deciding on whether to keep the PG in it now or not, a TH350 can be found very easily, will swap right in place of the PG and only takes a simple bracket change at the transmission shift rod to attach it to your current shifter. You might even be able to swap the PG for one at your local transmission shop if you're lucky.

Good luck with the engine swap and let us know how it all turns out!

Feb 25th, 03, 02:54 AM
I agree with HS Joe, keep the P/G. All he's looking for is extra power and the 327 will deliver this well.

Kyle can change to a TH350 at a later time, or this time, but its extra work for him. As Joe stated, Kyle gets a TH350 with a 6-inch extension housing, a torque convertor to match the TH350, flex plate, change linkage, and he's done. Basicly, still alot of work and planning.

The only thing Kyle will need to find to complete the changeover from I6 to 327 V8 is throttle linkage, he can change to '69 cable, and the kickdown rod between the bellhousing linkage and the carb bracket. The rest is fall in-place. New radiator hoses and heater hoses. Maybe accessory brackets for AC compressor, alternator, and power steering pump, if equipped. He can use the same radiator, but, will need a V8 fan shroud and new V-belt. And V8 chassis mounts to bolt the V8 onto the existing subframe.

Go for it, Kyle!! graemlins/thumbsup.gif

Feb 25th, 03, 04:20 AM

Thanks for all of your input - after reading your thoughts, I will most likely stick with the PG but if I feel the need for extra/steadier acceleration (and you know I will eventually) I will look into switching to the TH350. Since this is the original PG trans that came with the car it may not have a long life, although it still runs smooth. I imagine after driving the straight 6 for the past two years, the upgrade to a 327 will be more than enough to subdue me for now but I will keep the thoughts concerning the Th350 close to heart.


Feb 25th, 03, 08:46 AM
See, Kyle's already thinking about changing.........won't be long now.........LOL graemlins/thumbsup.gif

67 Plum
Feb 25th, 03, 01:41 PM
You will notice almost as much difference going from glide to 350 as you do going from 6 to 327.
That said he will change soon , very soon. graemlins/hurray.gif

Feb 25th, 03, 07:35 PM

I made the move from a PG to a TH-350 on my 67 RS small block about two years ago and am very happy with it. The better boost from stand still is a kick in the pants and I wouldn't go back.


Feb 26th, 03, 10:02 AM
I had a powerglide with a 327 4bll, I installed a TCI kit and had a blast driving the car (in city). It was somewhat a dog off the line, but at around 30mph hold on!!!!. I have since gone with a 700r and the car now loves the highway and is a bullet off the line.(not an easy swap)

If you decide to swap out powerslug, go with an overdrive. Highway driving is sweet.