455

[newfx11]

I was wondering a couple things about a 455. I want to dump one in my car next year, but I'm still not sure if I should, or just dump a 400 in there. My questions are: where would I be able to find info on a stock 455 such as horsepower/torque? Should I dump the 455 in there? It isn't going to be a drag car or racer, I just want a little speed to go with the sleeper I'm building. Would it be a good idea to bolt on subframe connectors or weld in, and would it hold up to the 455? I've heard something about cars with the combination of T-Tops and a 455 without any frame mods that the engine can twist the body and break the T-Tops, but then again I've heard from other people that a 455 couldn't possibly do any body twisting unless it was highly modified. My only intentions are to minorly modify the engine with headers, carb, and manifold & cam kit. Any help would be awesome, thanks.

[MrMojoRisin681]

I'd get Subframe Connectors. Better to be safe than sorry. I'd go with Bolt on ones, and then weld them in. Most of the weld in ones for our cars require some modding. As for the 455 or 400 it all depends on what you want and what you can get. Certain year 400's will have more power over different year 455's. I believe parts cost around the same.

[newfx11]

I'm leaning toward the 455 more than the 400 actually, I just didn't know what to do about the connectors. I already knew I was going to get them but I couldn't choose between the two. I don't want to modify the floorboards, I've heard a few connectors required modifying the floorboards such as cutting stuff out in order for them to clear, but I don't want to do that.

[9T8W66]

Externally all Pontiac Engines look the same The difference between a 400 and a 455 are Bore & Stroke
400's have a 4.12 B and a 3.75 S
455's have a 4.15 B and a 4.21 S

There are a few other differences but those are the main ones
They both use all the same Intakes Heads Cams Headers Carbs Distributors etc....

455's are few and if you do find one they aren't cheap.
a 400 will make almost equal horsepower but less torque than a 455 all parts being the same.

I would go with the 400 because they are more available and they make great power. Trust me I've built a couple of 400 Trans Am's that were simple and would run with a stock LS1

[newfx11]

Yeah, after looking at eBay and trying to find a complete useable 455... makes me almost want to just find an SD and call it a day. The guy at this junkyard down the road wants like $300 for his 455, but I haven't seen it. My goal is to make some moderate horsepower. I don't know what a 400 or 455 makes stock as far as hp and torque, but after I find out I'll find the goal to shoot for.

[9T8W66]

Rated HP depends on what year the engine is and what Car it went in originally.
In 1970 top of the line 400's and 455's made the same HP 370 (rated)
400 Ram Air IV 370HP
455 HO D-Port 370HP
In 1971 GM dropped Compression on all Cars so the HP dropped as well
Chances are that you will find a basic 455 from a mid 70's Car.
These Ehgines only have between 200HP (`75-76) and up tp 250HP(`73-74)
You probably won't find a 455HO 335HP or a 455 SD (290) and these engines wouldn;t be Cheap.

Don't let those low HP Numbers discourage you a good cam with the right combination of bolt on's can make a very Fast Car.

[81DaytonaPaceCar]

You probably won't find a 455HO 335HP or a 455 SD (290) and these engines wouldn;t be Cheap.

Don't let those low HP Numbers discourage you a good cam with the right combination of bolt on's can make a very Fast Car.

Did you really say that you found a complete 455 for $300? And you haven't bought it yet? If the block is sound, that is a steal, especially if the crank is good.

Finding a good 455 block will be the hard part. Even 400s are getting scarce. The earlier in the 70s you can get the better off you are as the nickel content gradually decreased through the 70s for cost reduction, but that's really only important if you want to make really big HP.

The SD and HO motors are valued for their heads, but aftermarket heads (including aluminum) are as good if not better than the original SD/HO heads.

But they won't be cheap. Neither will a good crank.

All things being equal, if you can find a 455, I'd go that route as the costs will be identical to building a 400.

[meissen]

Get the 455 that Kristin is selling. Right in your area too, Cody, she's at 32 and Van Dyke.

[MrMojoRisin681]

Get the 455 that Kristin is selling. Right in your area too, Cody, she's at 32 and Van Dyke.

She is selling a 454 which is a Chevy Motor, A 455 is a Pontiac motor. It's an easy mistake for you guys with newer cars that have 'GM Corprate' engines.

[MattODoom]

Get the 455 that Kristin is selling. Right in your area too, Cody, she's at 32 and Van Dyke.

That's a 454, a Big Block Chevy. A 455 is a Pontiac motor.

[MattODoom]

She is selling a 454 which is a Chevy Motor, A 455 is a Pontiac motor.

Beat me to it!

[81DaytonaPaceCar]

She is selling a 454 which is a Chevy Motor, A 455 is a Pontiac motor. It's an easy mistake for you guys with newer cars that have 'GM Corprate' engines.

True dat my fellow 2nd gen peep.

BUT...the 454 would bolt in with some different motor mounts. You just need to get mounts for a 70 396 Camaro.

Not that I would do it...but it would be an less costly option...

[MrMojoRisin681]

True dat my fellow 2nd gen peep.

BUT...the 454 would bolt in with some different motor mounts.

Not that I would do it...but it would be an less costly option...

Depending on what motor originally came in his car, he might have to do some more stuff to put a 454 in. If he had a Pontiac engine in their he would have to switch the fuel line and the battery to the other side. And get a chevy bolt pattern tranny.

455's are torque monsters. I'd go with one of them if you can find it.

[81DaytonaPaceCar]

Depending on what motor originally came in his car, he might have to do some more stuff to put a 454 in. If he had a Pontiac engine in their he would have to switch the fuel line and the battery to the other side. And get a chevy bolt pattern tranny.

455's are torque monsters. I'd go with one of them if you can find it.

Yep, agree with everything you said.

The $300 455 sounds like a no-brainer to me...

[MrMojoRisin681]

There was a complete 400 with a TH400 for $300 over here on the west side last week. Not sure if it was running. I wish the guy would have posted it a couple months ago before I built my 350sbc.

When you find a good deal like that 455 jump on it, cuz they sell quick. Find out the block numbers so you know its a 455.