Engine building confusion

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DEVILSorchard

Not-quite-so-new-guy
Sep 22, 2014
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Ive been looking to build an engine this winter for my 82 cutlass to replace the 267 and I could really use some help getting the Olds and Chev small block thing straightened out. :wtf:

Some sources online claim differences in trans bolt patterns, motor mounts, alternators and a few other bolt on components. Other sources claim they are all there own engines completely separate and non compatible between, some sources claim Chev, Olds, Buick, Cadillac etc also used the same engines cross each platform on occasion. This was specific to the 350, 443, 455 engines. I couldn't find anything on 267 or 305's but a bit on olds 307's.

I thought a trip to the local PNP would set this straight in my head. Well from what I can see the 305 Olds and Chev look damn near identical, were these a cross platform engine? There's a nice looking 305 in an 84 cutlass brougham that looks promising, all the 305 / 350's from the Chev's are half stripped and exposed. There's also a f body Firebird with standard trans Id like to take but the 302 is junk. Any chance these would bolt up together?

The other big mystery is this 267 I almost can't see Chev and Olds making the same mistake and both building there own versions of this abomination. would this be the same engine or trans. bolt pattern between a Chev 267 and Olds 267? more specifically if it is the same engine who's bolt pattern is it, the Chev or the Olds bellhousing?

Id bought this car thinking a small block was a small block after Ive been collecting SBC parts here and there for the last decade. Thanks for any help links or advice getting this confusion straightened out.
 

FE3X CLONE

Comic Book Super Hero
Dec 2, 2009
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You're thinking about this too hard.

305 is a Chevy engine. If you find one in a Cutlass, it doesn't mean it's a 305 Olds. It's just a 305 Chevy in an Olds chassis.

GM started pulling this crap in the late '70's which was just the precursor to having one corporate engine for every make.

Olds's version of the 267 was the 260 and yes, it was just as anemic.
 

DEVILSorchard

Not-quite-so-new-guy
Sep 22, 2014
37
2
8
Thanks a lot, its starting to make a lot more sense. When id searched for differences in olds 305 and chev 305 it popped up with info on olds 307 vs chev 305. That just made everything confusing.

So Im assuming since im running the chevy 267 with th250 I can swap any 305 or SBC onto that trans. and call it a day.
 

FE3X CLONE

Comic Book Super Hero
Dec 2, 2009
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48
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I would assume you could but I've never messed with the Chevy stuff so I wouldn't be the one to ask.
 

CHRIS.O

Royal Smart Person
May 26, 2011
1,432
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You can literally pluck that 267 out and put a 305, 350, 400, etc in its place. Chevy engines of course. Externally they are all the same. The engine you have is a 3.48" stroke with a 3.5" bore. Tiny valves and poor performance. Gm dropped it. One of those mistakes theyd probably love to forget. To go to another chevy engine such as a 350 you may have to mess with throttle brackets and linkage but nothing that is too difficult. As far as bolting to your trans, yup a small block chevy will. However i couldnt tell you how long the trans would handle more power than it was designed for.
 

DEVILSorchard

Not-quite-so-new-guy
Sep 22, 2014
37
2
8
Awesome. thanks a lot guys.

Once I realized I was way over thinking things it was easy to google the correct answers. I was about to just start unbolting engines and transmission's tomorrow at the wreckers and try to fit random things together. This just potentially saved me a lot of work.
 

88hurstolds

Royal Smart Person
Jun 24, 2008
1,747
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No offence, I am surprised you are even tackling a project like this with these kind of questions. :lol:

You are going to have to make sure you have the right bell housing bolt pattern on your trans as well.
Chevys and BOP are different however the TH2004R was a universal bolt pattern, not sure about TH250 which is junk BTW...
Most likely if you increase the power output that TH250 trans isn't going to survive.

What are your goals with this project, just to get from point A to point B or to peel the tires and have fun on the street?

I would suggest a Chevy 350 if you want a little more power or a Chevy 305 if you are wanting to just get the car moving a bit faster day to day without the slug 267.
Going Olds would require changing the engine mounts, possibly the trans and wiring the battery on the drivers side to name a few...

If you were going to go all Olds I suggest you find a complete 307 car in the bone yard and grab everything from the frame mounts up...
Fan to flex plate, frame mounts to carb including the throttle cable.
From there you can upgrade to a 350, 403 or even a 455 will drop in if you use the stock exhaust.

Good luck!
 

DEVILSorchard

Not-quite-so-new-guy
Sep 22, 2014
37
2
8
Lol yes I know these questions sound very newbish for someone talking about swapping engines and considering a manual trans swap at the same time.

I've been buildings street ported mazda rotaries, turbo ford 2.3's a few with huge holset turbos, megasquirt ecus and modified twin cam Volvo heads strapped on (folvos we call them) and scratch building harley frames. I'm not new to the custom auto scene or fabricating parts. Wikipedia set me on the wrong path when I'd read the 267 was its own engine entirely. I can see now that was regarding bore size and there's a few bore stroke charts that listed 307's at that point I already made the assumption that was a chev 307 and olds had its own. Figuring out what's compatible when I'm searching for answers that didn't exist made this even more confusing. Fe3X was right on the money, simply over thing things.

My power goals are relatively conservative 250-300whp with a blow through turbo setup. I'd asked these questions because I was trying to figure out what's compatible for a long rod, small bore, heavily over squared engine combo to limit the torque curve of a turbo engine. Something like 3.5 - 4.00. Bore 3.00 stroke and 6.2 rods and play around with heads and valve sizes to lower the power and let me run some decent boost. I'm used to the laggy and explosive power curve of a turbo engine and my driving style has adapted for this kind of power curve and it would sound awesome.
 
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