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455 big block or 350 small block

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455 big block or 350 small block

loudthunder loudthunder
New User | Posts: 12 | Joined: 09/09
Posted: 09/14/09
01:22 PM

I would like to get some opinions on what true pontiac fans consider to be the better motor for a 1972 lemans sport, a 350 pontiac or a 455 pontiac. The lemans will be used  for street use, mostly just cruisin but occassionally blowing the doors off from a mustang or a foreign match box car.I appreciate your opinions thank you.  

Pontiacman8 Pontiacman8
Moderator | Posts: 5778 | Joined: 02/08
Posted: 09/14/09
01:36 PM

Ok Pontiac never made a small block.
I'm partial to the Pontiac 350 and 400 over the 455 but it all depends on what you want and what you already have what is in the car now.
I have a 1979 regal in the readers rides section that is powered by a Pontiac 350.  
Engine builder,self taught auto body guy.
Horsepower sells engines and torque wins races


barneyformula barneyformula
Addict | Posts: 3306 | Joined: 01/07
Posted: 09/14/09
01:39 PM

I assume you mean the original numbers matching 350? It all depends on what you want. The 350 is a great cruiser with a few mods such as a mild cam, dual exhausts and 4 barrel carb/intake. With an overdrive trans swap and some decent gears (3.42-3.73) it will perform very well and still give you mileage when cruising on the highway. On the other hand a 455 built to the same level will do the job without the deep gears and overdrive trans. Likely the mileage will suffer if that's a concern, because you still have to feed 455 inches compared to 350, but it will have huge torque!
A little help... 'cause we don't all have to learn the hard way!

flynryan flynryan
User | Posts: 151 | Joined: 01/09
Posted: 09/14/09
01:46 PM

Torque rules on the street. Only so much power can be used in 1st gear on the street. Once you hit 2nd with a 455, say goodbye as the torque continues to pull through top gear. I have been around street racing for 15 years. As the street cars have gone from 13's to 12's to 11's and a few 10 second rides, the top fastest cars on the streets in our region are all 455's... a 12 second 455 car can take down a 10 second small block on the street. The small block needs to hook hard with RPM and gearing on a prepped track to run that 10 seconds. That cannot be done on the street. The 12 second torque monster can leave with ease, and then force the power down once out of 1st gear pulling all the way.  

creepyracing creepyracing
User | Posts: 204 | Joined: 06/08
Posted: 09/14/09
07:31 PM

Dude this is a no brainer. If you have access to both, more cubes are always better. Both pontiac motors are the exact same size externally the differances being bore, stroke and the all important main journel size.The 455 has a very heafty 3.25 main while the 400 and below blocks have a still bigger than chevy 3.00 main.If you really want to "blow the doors off a mustang or foreign match box car" go with the 455!!!!  

loudthunder loudthunder
New User | Posts: 12 | Joined: 09/09
Posted: 09/14/09
08:52 PM

Just wanted to say thanks for all of yours opinions. I'am new to the pontiac world of performance. Back in 1988 I owned a 1980 transam all I did was beat it into the ground. Now older I want learn more about the performane of my car. Not just push the gas pedal to go faster.But I still love that feeling. Looking forward to years of pontiac performance. Thank you, keep cruision..  

kiwigto kiwigto
New User | Posts: 6 | Joined: 07/09
Posted: 09/16/09
02:40 AM

Yeah I'm new to the Pontiac thing as well. I think I've owned every marque of muscle car in one form or another...including an RT charger, 69 mach 1, Aussie GT Falcons, commodores and I dont think I've had so much attention and/or respect at shows or on the street etc. as since I bought my 66 GTO - especially with a 455. Everything I have read to date points to the 455 (providing its the right model)makes it very hard to beat. Do your homework though. Just my 2 cents  

Opontee Opontee
Guru | Posts: 1422 | Joined: 07/09
Posted: 09/16/09
02:21 PM

I built a 455 for my 77 FB way back when and got 26 on the highway for fuel mileage. With a good cam and 2.41 gears, it will still smoke just about anything out there. At least mine did.  
Anna Mae quit. Opontee

blackbird72 blackbird72
User | Posts: 186 | Joined: 08/07
Posted: 09/25/09
06:32 PM

Another vote for the 455 here- I've run 350's, 400's and 455's in my '72 Firebird, but I'd have to say I had the most fun w/ a 455. It's not the most economical engine, especially if you built it to run (9-11 mpg w/ 850 DP/ Torker II w/ no.64's, RA IV cam, big headers), but you can't beat the performance- low 12's on street tires.

I'm planning to build another one soon, this time w/ ported 6x-4's, Probe SRS flat tops and PPR 4340 I-beams, but sticking w/ the RA IV (Crower 60919)- should be a fun motor.