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Drew Dowdell

Question about the old days of GM powertrains.

23 posts in this topic

Not having much access to the older GMs back when there were divisions, I wonder if you guys can enlighten me on some things.

Buick had a 455 and Olds had a 455.

Buick, Olds, Chevy, and Pontiac all had 350s

I'm sure there were some other overlaps of displacement as well.

Did all of these engines have dramatically different personalities? For example, why did the Chevy 350 survive while the Rocket, almost nearly as well renowned, was canceled in 1990 and Pontiac's and Buick's 350s canceled much earlier. I can understand the reasoning behind wanting just one common V8 engine design, but what I'm asking is why one of them won out over the other.

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If I were looking at old engines, I'd want a Buick 455 over a Rocket 455 because of the torque, but then I'd have to watch out for intake manifold problems. Or I'd want an Olds 350 over a Chevy 350 because they are smoother running and easier to tune. </completely made up examples>

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I know there was a big difference in transmissions. Chevy's powerglide, Olds's Hydramatic <the WINNER!>, Buick Dynaflow were all very different.

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Not having much access to the older GMs back when there were divisions, I wonder if you guys can enlighten me on some things.

Buick had a 455 and Olds had a 455.

Buick, Olds, Chevy, and Pontiac all had 350s

I'm sure there were some other overlaps of displacement as well.

Did all of these engines have dramatically different personalities? For example, why did the Chevy 350 survive while the Rocket, almost nearly as well renowned, was canceled in 1990 and Pontiac's and Buick's 350s canceled much earlier. I can understand the reasoning behind wanting just one common V8 engine design, but what I'm asking is why one of them won out over the other.

No idea, but I'm assuming Chevy ultimately won out since they were the biggest division, biggest # of sales, and the sheer # and ubiquity of SBCs over the decades..

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They were all different, but BOP (Buick, Olds,Pontiac) had alot of commonality. Generally speaking though, the Chevy engines would make more power. That, in combination with the huge volume advantage, gave Chevy the budget to develop even better engines.

Balthazar could give you a much better overview of the BOP stuff, I'm sure. But here's an example where Chevy had the advantage. Chevy's big blocks (the mark IV engines) tended to breathe better than the BOP 455s. That's just one example.

One other tidbit: the BOP 455s were not technically big blocks at all, their external dimensions were the same as the smaller displacement engines whereas the Chevy big and small block engines had little to no commonality.

OK, one more:

While all of the divisions used TH350 and TH400 automatic transmissions, the mounting bolt patterns were different. So, you could not use a TH400 from a GTO in your SS 396 Chevelle when you blew the trans at the track.

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Don't forget Pontiac had its' own 455, unrelated

to either the tri-shield or the rocket.

Chevy and Buick had the 3.8 liter V6, chevy's

was the 229, Buick's was the famous 231.

Great reason why i can't argue with Balthazar

about using cu. in. instead of liters.

Then again CCs are even MORE accurate.

The super-downsized 4.3 V8 is oft. confused w/

the "3/4 of a SBC350" V6 with the same

displacement from the same basic era.

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Walked away form the computer and immediately

thought of the Olds rocket-based 307 that powers

so many '80s cars & Chevrolet small block 307

that served as the base motor for half of the '69

Camaro's lifecycle. IIRC the 307 replaced the 327

as the F-body (and other Chevy '69 m.y. cars)

base V8 motor in the spring of 1969.

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Well... yes, but what makes them different? Was Old's 307 a better runner than Chevy's?

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Well... yes, but what makes them different? Was Old's 307 a better runner than Chevy's?

I would think being that the Olds 307 was from the '80s and the Chevy one from the late '60s-early '70s, the Olds would be a low-power motor with all the emissions equipment, etc. GM V8s in the '80s tended to be pretty low on power, IIRC. Neither were really performance motors, though.

Interesting factoid from Wikipedia--the 1990 5.0 L Olds V8 was the last carbureted passenger car engine on the market in the United States. Wow... carbys still in 1990...that's old school.

Edited by moltar
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The problem with these questions is that back then people where Chevy fans or, Buick fans, or Pontiac fans... not GM fans. So we will need to get several perspectives (and maybe take a look at vintage magazine comparos) to really answer your questions.

I can say this though, the Chevy 307 did not replace the 327. The 307 replaced the 283 as the base "workaday" Chevy smallblock. Although the 283 had some performance trims stretching back to '57, the 307 never did. The 327, on the other hand, was almost always a performance engine - and it was replaced by the 350.

As for the Olds 307, I suspect that it served the same purpose as the Chevy 307.

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The Olds 307 is a bit of a dog, but it idles pretty smoothly.

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>>"Buick had a 455 {Pontiac had a 455} and Olds had a 455. Buick, Olds, Chevy, and Pontiac all had 350s.

Did all of these engines have dramatically different personalities? For example, why did the Chevy 350 survive while the Rocket, almost nearly as well renowned, was canceled in 1990 and Pontiac's and Buick's 350s canceled much earlier. I can understand the reasoning behind wanting just one common V8 engine design, but what I'm asking is why one of them won out over the other. "<<

To start off, yes: the BOP 455s were unique and definately did have different personalities. I don't know that'd I'd call them 'dramatically' so, but there were distinctions aplenty down to exhaust sound. Traditionally, the division's proprietory engines were built in separate plants, so undoubtedly production capacity played a major role --in addition to the pros/cons of each engine-- in determing which engine would continue to be built in the face of corporate consolidation. Chevy got the nod for the SB V-8, Buick got the V-6 (back) and Pontiac got the 4-cyl. BTW: this for me is the 'beginning of the Great Downturn' over anything else.

>>"I'd want a Buick 455 over a Rocket 455 because of the torque, but then I'd have to watch out for intake manifold problems."<<

Not a real problem there.

>>"They were all different, but BOP (Buick, Olds,Pontiac) had alot of commonality."<<

No; there was very little interchange going on... in the case of the big displacement motors... umm, none that comes readily to mind beyond clear-cut bolt-ons like carbs. But intakes, heads, pistons, rod, cranks, pans, timing covers, exhaust-- all proprietory.

>>"But here's an example where Chevy had the advantage. Chevy's big blocks (the mark IV engines) tended to breathe better than the BOP 455s. One other tidbit: the BOP 455s were not technically big blocks at all, their external dimensions were the same as the smaller displacement engines whereas the Chevy big and small block engines had little to no commonality."<<

Only Pontiac's blocks were the same size externally; Buick & Olds had definate small- and big-blocks. And if it's not apparent; a division must have one in order to have the other... therefore relegating Pontiac to having... neither (Pontiac technoids often refer to them as 'mid-blocks').

And Chevy engines tended to 'breathe better' if you only looked at intake flow #s, but Buick's flow ratios were much better than Chevy BBs and equal to the SBs. Pontiac V-8 ratios were also superior to Chevy's BBs... where the track differences came into play were factory & aftermarket parts support. Strong Pontiac & Buick V-8 aftermarkets have only come online in the last 10 years.

>>"While all of the divisions used TH350 and TH400 automatic transmissions, the mounting bolt patterns were different. So, you could not use a TH400 from a GTO in your SS 396 Chevelle when you blew the trans at the track. "<<

Yeah- Chevys & Cadillacs had their own bolt patterns, but BOPs did interchange.

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>>"GM V8s in the '80s tended to be pretty low on power, IIRC."<<

Very nice of you to... again.. make an effort to point out just GM's past deficiencies as if they were alone in this era... but bear in mind the '80 were universally sucky- this is when a ferrari struggled to pull a 15-sec 1/4 mile.

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Thanks Balthy. My Buick 455 over Rocket 455 was a completely made up scenario just to give an example of the situation I was looking for.

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my dad's putting a 455 olds into where a 350 olds was, i don't know about the other ones, but he showed me that the 70 or 71 engine had nodes in the heads so "air injectors?" could be retrofitted into the design much easier for emissions. I don't have much comparison knowledge, but the 350 w/ a 4 speed could move ...maybe better than a 305 91 camaro auto.

it's been a year or 2, maybe 3, but Car Craft compared engine builds of big motors, chevy 454 buick, olds 455 i think a cadi 502...done up with aftermarket

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I was hoping that you'd chime in on this Balthazar. Just one little clarification of my statement that there was a good bit of commonality in the BOP engines: I was referring to externals (such as the trans bolt-pattern and accessories) not the internals.

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No prob- was out of town.

It was my manner of interpretation - when talking about engine commonality, a transmission doesn't enter into the discussion IMO. Still > "good bit" = transmission bolt patterns (BOP only), alternators and.... carbs. Would radiators be included? Doesn't fit the assessment, IMO.

The only reason I dwell on this is, to the unwashed, the implication suggests that mass sharing is all GM has EVER done... and this gets extrapolated from the '70s and later, back to 1908, and widens to include 'platforms' (anachronistic term RE this era), engines, etc, etc. I hate to see that happen. I've read on vintage forums, people asking which Impala frame would work best under their 88 (as a bolt-in); it's assumed everything... ALWAYS interchanged when in fact for the bulk of 80 years, most stuff didn't. Makes me bristle.

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No prob- was out of town.

It was my manner of interpretation - when talking about engine commonality, a transmission doesn't enter into the discussion IMO. Still > "good bit" = transmission bolt patterns (BOP only), alternators and.... carbs. Would radiators be included? Doesn't fit the assessment, IMO.

The only reason I dwell on this is, to the unwashed, the implication suggests that mass sharing is all GM has EVER done... and this gets extrapolated from the '70s and later, back to 1908, and widens to include 'platforms' (anachronistic term RE this era), engines, etc, etc. I hate to see that happen. I've read on vintage forums, people asking which Impala frame would work best under their 88 (as a bolt-in); it's assumed everything... ALWAYS interchanged when in fact for the bulk of 80 years, most stuff didn't. Makes me bristle.

Understood and agreed.

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i've been told a plus on the OLDS side was that if you got a performance Olds they actually matched the pistons to the cylinder heads... how cool is that. they were labeled in some fasion A B C D.

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One little tidbit: There was an Olds "big block" V8--the Olds 330 & 350 (+ later 260, 307 & 403 CID) were "low block" engines with a lower deck height than the 400/425/455 engines. As a result, the bigger engines look wider when you see them under the hood; even the intake manifold on the bigger engines is wider than the one used on the smaller displacement versions with the lower deck height.

I believe the same hold true for Buick; the 350 and 455 were different blocks, IIRC (I know the earlier 300/340 CID engines were different than the 400/430 CIDs anyway).

Not sure if Pontiac changed deck height going from the 326/350 up through the (389?), 400, 421, 428 & 455 either...wouldn't be surprised, given the lengthened stroke, especially on the 455.

One other thing: I remember hearing that some of the V8 engines were easier to tune for compliance with ever-stricter emission standards than others, so GM would concentrate on bringing those engines up to snuff, rather than spending all the engineering $$ trying to get all of them to comply.

Edited by NeonLX
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I believe the only different Pontiac V-8 deck height-wise was the 301. Nothing from it interchanges with the others.

Buick 455 is unquestionably a different casting than all other Buick V-8s.

FYI- there are 3 (it may be 4) different casting #s for the Buick 455. I have (2) #1238861's.

Buick 350 may indeed be a lower deck height engineering take-off from the big block, if external dimensions are any indication: 350 : 28"W x 30"L x 28H ... 455 : 28"W x 30"L x 30H

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Sheesh, I'd clean forgot about the 301 CID Pontiac V8. Thanks for the reminder!

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Remember the mildly-tuned 396 that was used in the 1969 full-sized Chevy cars? It had a 2V carb and a lower compression to run on regular fuel. I think this version was available only for the '69 model year.

Friend of mine had one of these mills in his '69 Caprice.

In 1970, the 400 CID small block was introduced and it became the larger displacement, mildly-tuned option for those cars.

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