# 1973 455 with turbo 350



## par4n1 (Jan 28, 2010)

I located a 73 Catalina with 455 and tranny for 400.00 ( cant here it run ) i did a little reserch and the 73 455 was rated at 250 HP. Would the problem with performance be mainly the heads or should I just pass on it and wait for something with more potential. engine has 75k miles.


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## facn8me (Jul 30, 2011)

I would think any 455 and trans would be worth $400 no matter what ya needed to do.


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## Instg8ter (Sep 28, 2010)

If its a stock bore and not rusted or cracked its worth it...heads and cam are what make the HP and tell it when to come on strong, throw on some 96cc heads and a performance cam and your at 400 HP in no time


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## geeteeohguy (Feb 2, 2008)

73 is a great year for a 455. The price is a steal, IMO.....if it's in rebuildable shape. The HP ratings changed in '71-'72 to 'net' HP for insurance reasons. The actual HP and torque of the engine is pretty high. With the stock heads, it'll probably be okay to run on pump gas, too.


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## par4n1 (Jan 28, 2010)

I now know it is a 400 turo that comes with the car so.....I can buy the 455 with the turbo for 400.00 or I can have just the motor for 300.00. I am a little money conscience with all the parts I have been buying but I can afford the tranny as well but I thought to keep the powerglide in my car. Will the 455 work well for eithertranny and should I go ahead and get the 400 for the extra 100.00? 














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## Instg8ter (Sep 28, 2010)

for 100.00 grab the Tranny, with 75,000 it should still have some life in it if it was not abused and they are pretty bullet proof.


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## facn8me (Jul 30, 2011)

It will be a long shaft and drive shaft work will be needed with the 400


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## likethat (Oct 5, 2007)

There was a 73 Catalina convert at the yard back in St. Louis. It had a 455/400 in it. it was a shame to see it there. The car was in very good shape. The top was toast but the paint was still decent and really no rust. You can not buy cars from this yard I have tried in the past. I got the 455 and tranny for $250. At least I got its heart before it was turned into a Hyundai.


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## geeteeohguy (Feb 2, 2008)

Yeah, with the long tailshaft TH400, you can change out the driveshaft or swap on a short tailhousing.....easier/cheaper to have a 'shaft fabbed up, IMO. You don't want to run the ST300 2 speed trans with a 455. Powerglides never came in Pontiacs.


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## Instg8ter (Sep 28, 2010)

wonder how long it would take the 455 to turn the ST300 into a blender??


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## jetstang (Nov 5, 2008)

Everything I've read says the ST300 is a really tough tranny, not good for mods, but will take all the Pontiac torque.
Per my tranny guy, the longshaft BOP tranny is actually a turbo 375. It has a turbo 400 body, and turbo 350 output shaft, so you should be able to use any 350, and maybe ST300 driveshaft and have it modified. I was happy to find this info as I couldn't find the turbo 400 output shaft. For $100, I'd take it for sure. Nothing better than a 455, 400 and a 12 bolt, 10 bolt will sufice.


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## 68greengoat (Sep 15, 2005)

geeteeohguy said:


> 73 is a great year for a 455. The price is a steal, IMO.....if it's in rebuildable shape. The HP ratings changed in '71-'72 to 'net' HP for insurance reasons. The actual HP and torque of the engine is pretty high. With the stock heads, it'll probably be okay to run on pump gas, too.


I have a '73 455 with stock heads and a mild cam(I have no specs on the cam). As GTOGUY said, it's very streetable on pump gas. As mentioned, 96cc heads would be ideal.


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## par4n1 (Jan 28, 2010)

Ok I am gonna start sounding even moe dumber:confused I only said I had a powerglide because it was a GM two speed. I had no idea Pontiac didnt have a powerglide so I bet I have the ST300 two speed. Now I think I know the next answer. Does the turbo 400 out perform my current ST300 two speed?


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## jetstang (Nov 5, 2008)

par4n1 said:


> Ok I am gonna start sounding even moe dumber:confused I only said I had a powerglide because it was a GM two speed. I had no idea Pontiac didnt have a powerglide so I bet I have the ST300 two speed. Now I think I know the next answer. Does the turbo 400 out perform my current ST300 two speed?


The turbo 400/375 is the heaviest duty trans GM made in the day. The 2 speed is lighter, but the gear advantage of 3 speeds is superior. Plus, the 400 takes mods better than the 300, and has been used for performance far more than the 300, thus more parts availability..


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## BearGFR (Aug 25, 2008)

par4n1 said:


> Ok I am gonna start sounding even moe dumber:confused I only said I had a powerglide because it was a GM two speed. I had no idea Pontiac didnt have a powerglide so I bet I have the ST300 two speed. Now I think I know the next answer. Does the turbo 400 out perform my current ST300 two speed?


Don't sweat it - you're not the first person to assume that a 2-speed GM auto must be a Powerglide, and you won't be the last. Some parts are interchangeable between the two.

TH400 is better and certainly stronger, especially if the intermediate sprag clutch is updated.

Bear


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