84kabam

I got the idea yesterday that i want to swap out my 350 small block in place of a 455 big block. Obviously theres a deal of modification to make this work but has anybody ever tried swapping a 455 into a third gen trans am? Mine is an 84 and came stock with a 305 which was later changed to a 350. Also what transmission would mate up best? thanks

RB83L69

A 455 is not a big block.

It's a Buick, Olds, or Pontiac motor. Those don't have "big" or "small" blocks. Their blocks are all kind of "big". But they're not "big blocks".

People get that idea all the time. Occasionally someone follows through on it. Usually those who are most successful, and experience the fewest detours and left turns down dirt roads and other frustrations, are the ones who are already familiar with their brand of choice; have lots of parts saved up here and there; know other people that also have parts, and knowledge about what fits and what doesn't; etc. It's discussed quite frequently. There's a "sticky" at the top of this forum about Pontiac swaps.

You can be 100% certain that it will cost you a great deal more than putting a Chevrolet motor in one of these cars; even if you get the motor for free. On the other hand, any "free" motor you're likely to come across, will be some gas-guzzling smogger pig out of Grandma's land barge left over from the 70s. In no manner way shape or form a "performance" motor. People will come back and tell you all about "but the 71 GTO 455 made 400 HP" or whatever; just remember, that "free" motor isn't out of a 71 GTO. It's out of some 74 Bonneville or something, and made 200 HP - about on a par with the 305s in some of these cars. Of course it will have 455 CID of torque, regardless; same torque you'd get out of any motor of like size, including a Chevy 454, a F*rd 460, Mopar 440, etc. etc. etc. Ignore the monkey-spank about how "Pontiacs are 'torque monsters'" because it's just that, monkey-spank. Cubic inches are torque monsters, not brands of cast iron. But if you do the research and come up with good performance parts ($$$$$) instead of the 70s smogger crap that you usually see laying around, you can build a helluva strong runner.

Do your research carefully, before you any spend money. You'll likely find that you'll have as much money in it by the time you're done, as you would if you got a LS1 and dropped that in instead. Don't do it because you think it'll be cheap.

Project: 85 2.8 bird

shorter, more informative version:

check out the Pontiac V8 swaps sticky

KrisW

iTrader: (5)

Don't forget that Buick/Olds do have small and big blocks. Just Pontiac that used the common block. Just a little FYI, no flame intent here.......

RB83L69

No "small" and "big" blocks. No flame intended.

The bore spacing is the same for all displacements in each of those brands. A Pontiac 301 has the same bore spacing as a Pontiac 455, for example. Uses the same cam, for instance; which means that the block is the same length, the lifters are in the same place, everything is spaced front to rear the same. Heads interchange (although accessories that bolt to different head combos can be a problem for some of them).

Contrast that with the Chevy SB vs 366/396/402/427/454; or the F*rd 260/289/302/351/400 vs the 429/460; or the Chrysler 318/340/360/400 vs the 383/440.

Pontiac and Olds do both have "short" and "tall" deck blocks; just like the Chevy big block has short and tall deck, the F*rd Windsor motor has different deck heights for the 302 and 351, etc. That isn't the same thing as "big" and "small" blocks.

So, once again, there are no Buick, Pontiac, or Olds "big" and "small" blocks.

84kabam

ok so now that we have the big and small block dealt with back to the main question i have....how hard is it to put a 455 into an 84 T/A and what modifications if any need to be made?

Street Lethal

iTrader: (16)

I agree with RB. If all you're after is you're ride being very distinct from everyone else's, that's one thing... but as far as power, a 400-sbc can make just as much torque as the poncho, and will be a whole lot easier to install.

But if you're heart is set on it, the only real difficult part you'll encounter is the engine mounts.... and transmission adapter plate (if you go with, and build up you're stock tranny, that is).

I honestly wish that the Pontiac division employed a Third Generation Firebird with true Poncho power.... but unfortunately, we don't get to make such decisions. We can of course, but not legally (EPA wise).

As for Pontiac engines being exactly the same, they most certainly are... but the factory ruined the 301 version (didn't they cut it down too much), and is honestly only good for a boat anchor.

KrisW

iTrader: (5)

Just trying to make this easier on the guys attempting this that don't know.......
Pontiacs are interchangeable mostly except 265/301
Olds uses a different engine block size and intake manifold for their big block 400-455
Buick has three engine families with no interchangeable parts;
nailhead 322-425, small block 215-350, and big block 400-455
I just want people to know the difference in case they get a "good deal" on used parts (which I love) so that they are not stuck with something they can't use. The buick v-6 does interchange many parts with the small block family also.......

SOLID LIFTER

Buick did have a small and a big block.

Bore spacing SBB: 4.24", BBB: 4.75"

Here's a pic of a 350 small block buick gasket on a 430 big block.

Street Lethal

iTrader: (16)

Great pic. I'm 'pretty' sure the same exact thing also applies to the Olds' 425 block, compared to it's 455 block. I think the 425 in longer (not sure)...

As for that 430 Buick pic, can you imagine that freaking thing bored and stroked? My goodness...

LT1guy

iTrader: (1)

Everyone's answer to these threads is always "get a 400 Chevy", and I'm just curious, how hard are they to find in other parts of the country and how much do they typically go for? Here, you can rarely find one...if you do, the owner knows what he has (no good deals), or its been used up. The last one I bought ( a disassembled and cleaned short block) was about $300, and that was 15 years ago...and it was a good deal then!
I'm not trying to save money with my Pontiac swap (cost isn't the issue, I'm building it because thats what I want), but I don't see where a Pontiac has to cost that much more. Once you consider the lower intitial cost of the core engine, the Pontiac only becomes much more expensive when you start replacing everything, and at that level its still not that much more than a SBC...and for the cost you get 55+ more cubes!

Street Lethal

iTrader: (16)

The four bolt main blocks are very expensive, the two bolt main blocks still sell for around $300-$500 (over here they do, anyways).

I think it's awesome that you went with a 455, that thing must pull like a raped ape. But the benefit of a 400-sbc, of course, is that it plops right in. Nothing, other than the tuning, needs to be changed.

LT1guy

iTrader: (1)

I agree with easier, and to an extent cheaper...say, if you already have good parts on your existing small block that will work with your 400 buildup. If you are starting from scratch, though, and are putting aluminum heads on either one, you will come out close on price.
My Pontiac swap is just getting started, but should put out 800+ on a mild tune.

KrisW

iTrader: (5)

Awesome swap, man!! I hope to get started on my next Buick powered f-bird soon. You guys with BOP engines are making me wish I would have kept mine longer!!

RB83L69

The cost isn't only the motor itself; one has to deal with accessories, exhaust, a trnasmission, getting the torque arm mounted somehow, etc. etc. etc.

All in all, ANY foreign motor transplant into these cars, is not a trivial matter. It's not like back in the 70s for instance, when if you wanted a Chevy big block in your LeMans that had has a 326 or your Skylark that had a 350 2-barrel, you just got Chevelle stuff and slapped it in; it all fit as an assembly, seamlessly. Or, like the street rod people, where they have certain "universal" frame setups that they use as the starting point (early 70s Nova for example), and "kits" to stick just about anything on top of that.

Plus, there's the issues of getting this sort of thing to be reliable as a daily driver. Little things kill you; like intermittent wiring splices, transmission linkages, exhaust leaks, belts that won't stay on, etc. etc.

It always is SO FUNNY to see this "torque monster" crap about ANY foreign motor. These people must think that gasoline molecules wake up in the process of burning, and look around themselves, and say "Wow, this is a {insert motor partisan's favorite brand here} motor, I like this brand of cast iron ALOT better than that run-of-the-mill {insert commoner's brand here} crap that EVERYBODY's got, I think I'll release some extra energy!!!" That's so patently bogus, it's laughable. CUBIC INCHES make torque, not cast-iron brand.

OBTW: I'm sorry I'm wrong about the old Buick motors from the 50s and 60s. You're right, those old old old ones, came in a whole array of sizes and flavors. But, again, they're not "small block" and "big block"; they're "nailhead", "430", etc. FWIW.... most likely nobody will be trying to put their '63 Buick motor into their Z28 or GTA or whatever, but you never know.

Chevy 400s are usually a helluvalot easier to find than Ram Air 3 heads or HO W30 heads or stuff like that. The people who have Pontiac parts, or Olds parts, or whatever, won't be so worried about this. But the guy that has a "free" 455 that he found laying in his recently passed great-uncle's back 40, won't have those either; more likely, it'll be one of those 200 HP turds from the 70s. Those are NOT a good foundation, as they sit, for a performance build. It's true that they make 400 ft-lbs of torque, which is of course GREAT; but, their torque vs RPM curve makes a LG4 or L03 look like a high-RPM screamer. They're meant to be able to idle, with the air on full blast, steering wheel cranked full to the stop and held there, etc., and not die, while Grandma was heaving the anchor in the local A&P parking lot. They are NOT hot-rod motors. They require a fair amount of $$$, and/or familiarity with the right combos of parts such as pistons & head combos and the like, to get something that won't be a mutli-thousand dollar disappointment. The spank-off of "I've got something totally unique under the hood" goes away REAL QUICK, when you get waxed and humiliated by somebody with something completely ordinary that cost half the dough and took a fraction of the time and that actually just fits the car as it sits without hacking everything in order to graunch it in.

Anyway, as far as what's different:

Transmission (different bolt pattern where it meets the block)
Flex plate (different crank bolt pattern)
Accessories (nothing on the front of the motor, except the alternator itself in some cases, will interchange)
Torque arm (there are no BOP case transmissions that support TA mounting, except for 200-4R)
Exhaust (same as accessories.... although there are a few "swap" header kits out there)
Weight (front springs will need careful selection)
Wiring (all sorts of things are in different places on the motor; alt, sending units, starter, etc.)
Starting (batt on other side of car)

All in all, this type of swap is not for the faint of heart. Someone who has never done one, would be well advised to tackle a simpler vehicle first, and get a feel for the issues that come up; do some serious research, and not just listen to the partisans for the brand in question when they tell about what they would do, rather than answering about what the questioner should do; and evaluate the reasons for doing the swap in the first place. "I got the motor for free" (or "cheap") is NOT a good reason, because THE MONEY YOU WILL HAVE TO SPEND, WOULDN'T BE IN ACQUIRING THE MOTOR CORE ANYWAY. I can't emphasize that strongly enough. You'll end up spending literally THOUSANDS of dollars, thinking that you're "saving money" on a $50 core. It's different if you have the background. If you're one of th epeople that likes some one of those other motors, are familiar with them, have parts, have knowledge, have access to other parts and info, have another car to drive, have fab skills and equipment, and so forth, then it can be ALOT of fun, and the finished product can easily be competitive. On the other hand, if this is a "free" motor that just "landed" on you somehow, and it's your only car, and you've never done anything like this, and you don't have unlimited time and money, and you don't have welding and cutting and grinding equipment, and you'd be doing it in your apartment complex parking lot, then it's probably not a good idea.

Incidentally, my first several cars were mostly Pontiacs, from the 50s and 60s. I happen to really like them... which doesn't extend to thinking it's a good idea for SOMEBODY ELSE to swap one of those motors into their car. I went through this hell once myself, I guess it was about 30 years ago or so, and all I was doing, was putting a 65 389 long block into a 64 389 car (Catalina); things were different that I had no idea would be different, and it ALMOST didn't work AT ALL, because the crank wasn't compatible with the transmission.That's another problem with BOP motors; they didn't stay the same on the outside for decades, the way Chevy motors did. Not every part will interchange with every other part. Just another thing you have to watch out for.

Street Lethal

iTrader: (16)

So very true.

If I had a dollar for every time I heard a Pontiac enthusiast say, "You don't need to wind them up high, their torque motors", as if some torque G0D dwelled within only it's cylinder bores, I'd be a very rich man today....

LT1guy

iTrader: (1)

More cubic inches:more torque...which is why people say that about 455s (B,O, or P), 472s (Cad) and 500s (Cad). It has nothing to do with the brand per se. With stock rods most of the above are RPM-limited, but with the avialability of good, inexpensive aftermarket rods that isn't much of a concern. The best factory heads are tough to find for any motor, so the beef about that in a previous post isn't really legit. Any of the commonly available factory heads for the above motors can make an easy 500hp with a little porting and a good valve job; the Caddy heads (the early 76cc versions, which I see every time I go to the salvage yard) will support more than that. How many factory SBC heads will do that? I'm not talking about SB2s, or even older Bowtie heads...stuff you can find in a salvage yard. Aluminum heads are available for all the above mentioned motors if you want more, and yeah, they're more expensive than SBC heads but typically about the same or less for comparable BBC stuff.
BOP swaps aren't for the typical order it-from -Summit- and -bolt-it-on-crowd, but when people are doing far more complicated and expensive swaps (LT1 and LS1) it really isn't that difficult in comparison. At least with this type of swap, problems can be solved with a welder and a little ingenuity (or a few hundred $$$), and not with thousands worth of wiring, reprogramming, and all the little obstacles that come up (VATS, no provision for a mech speedo, running a return line, etc). I'm not saying any swap is better than another, just that there are different reasons for doing them and different ways you can go.

KrisW

iTrader: (5)

Amen to that, brother!! Sometimes being different is its own reward.........


P.S. Most of the time hard work can be substituted for cash outlay. The above reference to the wrecking yard parts is definetely applicable. If you're working on the cheap, even if you live in an apartment (like I did) and have to change transmissions in a parking slot with cars on either side (like I've done) or rebuild your carburetor on your living room floor, it CAN BE ACCOMPLISHED. You just have to decide how much sweat to dedicate versus money spent to avoid sweat. There are more BOP "good" HP factory parts in the wrecking yards near me than chevy any day. All the chevy guys here must outlay the bucks for anything other than swirl port 305 tbi heads, and even those aren't free (EVEN THOUGH THEY SHOULD BE!)

Street Lethal

iTrader: (16)

True, but most of these enthusiasts (that I encounter) are referring to 400 blocks, not the 455's....

Either way, I'm all for it. The Poncho engine belongs in the Trans-Am!

flyitlikustolit

see, it's comments like the above that make me glad RB doesn't get frustrated at the trolls and leave the board. that was funny as hell.

on a serious note, he's right, and so is LT1guy. for what I've paid to put together my perfect T/A, and rebuild my 350 into a 383 stroker and all that ****, i could have built a poncho, and be driving it more often. and honestly, i kinda wish i had. but hind sight is 20-20. I've got 8 grand in my car now, and quite frankly, had i spent that on the poncho block, i'd be done with the motor, as far as big stuff. all that would be left would be paint and interior.

but one thing about chevy, is that if your going to spend dough, and that isn't a concern for you, then you can build a chevy relatively cheap relatively easy. emphasis on the easy. for a first motor swap, i think a chevy motor is the best way to go. but if you've done it before, go poncho. that's my 2 sense. ( yes, i mis-spelled it wrong on purpose).

Street Lethal

iTrader: (16)

Comments like the above? What the heck are you talking about? I was agreeing with RB...

Hehe, diplomacy in action. How can both be right? RB is saying that a Pontiac engine is not too feasible... as you'd have to literally build around the block just to get it to function correctly (which costs $$$), while LT1guy is saying quite the contrary...

Yeah, but then you must factor in what RB was saying in the first place. You must factor in the transmission, suspension, exhaust... all adding to the budget. If you had the parts lying around, or had access to them cheaply, then yeah, go for it. But if you have to go out of you're way to purchase them, and put the car together like a jigsaw puzzle, it's really not worth it...

RB83L69

I don't advise against swaps; I advise against ill-prepared people doing inherenty difficult swaps with far from ideal motor packages, and diving into it for the wrong reasons (I got the motor cheap), without understanding all the ramifications.

I also advise against taking advice from partisans of whatever the particular swap motor might be, who will all tell you all about their Ram Air 3 motor that made 550 HP on pump gas that they got running off their buddy for $100 when he had to pay bail, and stuff like that; problem is, the guy that's posting the question doesn't have a Ram Air 3 motor, he's got the worn-out oil-burnign gas-sucking 2-ton POS out of Grandma's old 2-tone land barge from the 70s, that's been laying out behind the barn since the car got wrecked 15 years ago, and now it needs a complete rebuild because it's full of rainwater and wasp's nests. Which means, he's got to put big bucks into a rebuild before a swap can even begin. Big difference there.

Swaps can be fun. And there's nothing wrong with Buick, or Olds, or Pontiac motors, as such. What's wrong, is advising somebody that's never swapped anything into anything before, to hack up their daily driver to put some smogger pig land barge motor (as opposed to a high-perf strong runner) into it; and the reason is, when the guy falls for that, he's going to be riding the bus for about a year minimum, while he struggles with this whole confusing mass of crap that doesn't fit together; it's going to cost him MANY MANY TIMES whatever he is misled up front into beliveing it's going to cost him; he's going to have to irrepairably alter things about the car that he didn't even know were there (no going back); and in case he ever gets it done, and doesn't just give up and throw all that crap away, he's going to have something that he has to work on every time he tries to drive it, because some stupid little aggravating thing is going to fall apart. Simple stuff usually, like throttle linkage, or alternator wiring, or heater hoses touching the headers and burning through, or things like that; nothing specific to "Buick" or "Pontiac", nothing you'll read about in some manual or somebody's web page write-up, but totally disabling the car just the same.

Does anybody begin to sense that I might have seen this happen before?

five7kid

iTrader: (14)

To say nothing about having a car that you can't register in strict emissions inspection areas.

LT1guy

iTrader: (1)

What I think a lot of people fail to realize is that in the typical third gen engine swap, regardless of whether you are putting in a traditional small block 383/406 or something else, ALL of the above mentioned changes need to be made. Think your "good" Th700R4 behind that POS 305 is going to live behind your 383 or 406? Don't think you'll need a larger radiator, subframe connectors, larger headers, a better clutch/rearend/driveshaft, etc, etc ? If you have been modding your old motor, think the 600 Holley and Edelbrock Performer (or the TPI) are going to be adequate for the new combo? Fuel pump? I won't even get into tuning issues. Oh yeah, the car probably needs engine and trans mounts anyway cause they've never been replaced in the 200k that are on the typical thirdgen now, not to mention belts, hoses, water pump, starter etc...on most project cars, this all needs to be replaced anyway.
Why is it that the typical Pontiac motor is "some smogger pig land barge motor", when the typical small block is apparently a"a high-perf strong runner"? What was a 400 Chevy? IT was a "smogger pig land barge motor"! Heck, they didn't even offer it with a four barrel, and there weren't any performance variants. Until about 20 years ago, no one wanted them. Sure, they have lots of potential...if you're doing a full performance rebuild. If not, it's going to be a turd, sort of like Grandma's oil burning Catalina motor.
I realize some engine swaps do require some fabrication, but bolt on engine mounts, a different (cheaper) trans or adapter plate, and a set of headers aren't what I would call "hacking". An engine swap of ANY kind probably isn't a good idea if your third gen is your sole means of transportation; buy a beater, because things will take time, whether its working out swap details, waiting on parts or the machine shop, or just life getting in the way. Wires burn on headers regardless of what brand engine is in the car, and there will always be fitment problems and minor changes that complicate any swap, even if its a 305 to a 350 or 400. You realize at 2am that your existing one piece rear main type flywheel won't work on the new motor, or that the throttle cable is too short for the hi rise intake you just installed. Stuff happens.IF you don't have the time, money, skill, tools, or patience for an alternative swap, its doubtful you have it for a normal one either. Its not rocket science, guys...I would agree wholeheartedly if these points were made on the LT1/LSx board, but not here...if you can't overcome the simple issues that arise when doing a carbureted engine swap, you really need to consider taking up a new hobby, or at least sticking to smaller projects.
On the subject of budgeting for any engine swap: figure up what you think its going to cost ahead of time, then (at least) double it...after you have done a few, you'll be able to estimate it better, but there will always be something you didn't think of ahead of time.

five7kid

iTrader: (14)

You know what, guys, all of the real "information" required to answer the originator's question was answered with this: As in, https://www.thirdgen.org/techbb2/sho...hreadid=291473 .

Although the rest has been "interesting", to get , the useful information is limited to "check out the Pontiac V8 swaps sticky".

LT1guy's latest observations should be taken to heart, as a lot of what he said is applying to my simple 305 to 350 shortblock changeout. The big difference is, when all is said and done, I'll still pass emissions inspection/test, which there is no way no how I would do with a Poncho swap (which I wouldn't do to a Camaro, anyway). Or BBC, for that matter.

And, since I'm no Ponco expert, I can't even remember when Pontiac last made a V8. My Pontiacs are FWD V6's (and I love 'em)...

RB83L69

No, they don't.

For example, your 305 accessories will bolt right onto your SBC 400, if you picked heads correctly (69-up... tough to find ones that meet that spec I know, but whatever). Your exhaust ports will be in the same place; no fighting the steering column or the frame or the motor mounts with it. Your battery will be on the same side of the car. Your bell housing bolt pattern will be the same. Your fuel lines will go to the same place. Your throttle linkage will fit and work. Your valve covers won't hit the brake booster. Your alternator will be in the same place. And on and on and on and on; all manner of things will fit and bolt up and and work, that WON'T on Grandma's 74 Buick's 455.

You ever seen the look on somebody's face when they put some one of those giant turds in their car, thinking that Grandpa's 75 Olds 98 motor was going to be a "torque monster" and defy the laws of physics somehow since after all a 70 4-4-2 had a motor about like that and was fast as hell, and their car goes slower than it did before? After no telling how many thousands of dollars and man-weeks of labor and however much irrepairable hacking on the car and riding the bus, and now their car is not only not faster, but rather slower, than it was before?? I have. Let me tell you, it's not pretty.

What I think alot of people fail to realize is, that telling a beginner to this hobby that is so unfamiliar with the pitfall possibilities that he doesn't even realize how different a Pontiac or Olds motor is from a Chevroler one let alone detais of what the differences are, to put some old smogger luxo land barge pig that needs rebuilt into their 3rd gen, is NOT doing them a service.

flyitlikustolit

Lethal - I wasn't referring to your post at all. I was talking about RB's. everytime he lays down what he's seen, done, or heard, or (usually) known, he words it in a raelly funny way. it cracks me up. that's what i was saying. I wasn't making any jabs at you, or what you said.

I think they're both right, but on different grounds. Rb is right... if you've got a decent motor (read: complete, no rebuild necessary, with good flowing parts) just LAYING around, like 18inchboyds does, (his dad drag raced a 77 firebird) then doing this swap is a great idea, assuming you understand whats involved, and you have a parts chaser to tool around in for a year until you finish the car enought to daily drive it. and he's also right because unless you've done 4 or 5 motor swaps, anything you change that's just a little different is gonna have bugs that will have to work themselves loose in order for you to find and correct them. it's just a fact. that said, if you're replacing everything in your car anyway, like i did, then exhaust, suspension, and all the other **** besides the motor isn't extra..... it's gonna cost the same to fab a complete exhaust for a 350 as it would for a 455. after the manifolds or headers, it's almost identical. you still have to route pipes to the axles, over it, and out the muffler and tail pipes. and the suspension and torque arm stuff... no, there isn't a trany that will "bolt up" that has TA provisions. that's why spohn is in business. while it's things like that that make this swap inherently more expensive than a budget 350 rebuild to drive it, i don't think anyone seriously (SERIOUSLY) considering this swap is looking for "budget" in order to just daily drive asap. or they'd build an SBC.

I think LT1guy is right because this isn't like trying to put an SBC in a porsche; so it's not going to cost $20,000. if you find a good core, you can build the motor with 6x4 heads, manifolds, and an rpm intake for a few grand. spohn x-members make it so that you can drop in any tranny, and the IA mounts make it so you can use SBC frame mounts. the only dicey part is manifolds or IA headers. the rest is just buy it and put it on, just like a performance SBC install. will it make 700 HP, maybe not, but frankly, 400-500 is good enough for some of us. while the whole "torque motor" idea is pretty funny, the fact remains (as was previously laid down by others) that because it has a 455 CID, it's gonna make power much easier than an sbc will. simple physics. add 105 CI to your 400 hp SBC and suddenly, it'll make 520 hp. i'd rather have a 500hp motor that will idle, lump along, and then destroy tires at will, all the while swilling 87 or 89, than a motor i have to wind up a little bit to wake up, on the verge of detonation, guzzling 93.

does that clarify what i was saying?

flyitlikustolit

and then after reading the last couple of posts, i think this has been beat to death at this point, but i'm gonna say this.

I have seen that look, and it really sucks. which is why i stand by what i said in the last post..... if you've done swaps before, this can be a great, fun time. but if you haven't, do an easy one first. if not, you're gonna get frustrated, get a headache, and light the whole thing on fire in frustration. it's not pretty at all.

five7kid

iTrader: (14)

Well, the originator hasn't been around lately. Besides, the answers to his real questions are contained in the sticky.

It's been fun, but I think it's time to say,

"Goodnight, Gracie..."