olds 307

[vette_7t9]

Well, i got a summer job so at the end of summer ill buy a g-body cutlass supreme. Can anyone tell me what can be done to this car to make it perform better? Any important mods to the 307? Can i interchange parts with any other engine for better performance?

[MagicRat]

IMHO toss the 307 and slip in a 403 or 455.
The 403 will bolt right in and is externally the same dimensions. The 455 is a bit taller and wider but is largely a bolt-in.

[vette_7t9]

where to find cheap 403? junkyard? from a truck? i really dont kno lol.

[Chris Stewart]

Do vehicles in your area have to be inspected for exhaust emissions?
Considering the computer controls on '81 & later Cutlass's, a fairly stock 350 will be more compatable with the stock carb & computer.
My neighbor was a used car salesman and he stopped by once to show me a '79 Malibu with a 396 big block Chevy installed. It looked stock except for the headers. Hoses, wiring and air cleaner looked factory...he didn't keep that one long.

[jmblimo]

Originally Posted by MagicRat

IMHO toss the 307 and slip in a 403 or 455.
The 403 will bolt right in and is externally the same dimensions. The 455 is a bit taller and wider but is largely a bolt-in.

Junk yard, if money is tight. Early 70's big Oldsmobiles for the 455, and late 70's (1977+), smaller body big Olds and Buicks for the 350 and the 403. The 403 and a 350 would be the easiest to install. My choice is the 403.

If you do have strong emission inspection in your area, you probably shouldn't do anything but replace stock with better condition stuff. They frown on "tampering".

[vette_7t9]

yea, i will check out junk yards and stuff. I just need to find a friggin cutlass.......theres not many around for sale. Theres a 1984 Calais, which the dealer is asking $2900. I think its ridiculously over priced, as the body needs to be repaired and windshield needs to be replaced. SO, im out to find more deals, hopefully will buy one soon.

[Stormysdad]

If you have a choice, look for a 75 or 76 350. 77 and newer were lightened, mainly in the heads which would lead to coking up problems especially around the EGR runners, which lead to broken rocker pivots. 75/6 would run forever as long as you changed the timing chain around 90K. Some people look for the early 70's valve covers as they said OLDSMOBILE on them and look really cool chromed, but I don't think they'll fit 75/6.

[cutlasskenny]

if you were looking to keep originality you can do a good bit to the 307, but if that doesnt matter to you then go bigger

[chevy70impala]

If you are still looking email me at [email protected]. I have a 84 calais W/ ttops, fiberglass w-30 style ram air hood and rear spoiler on it that i would sell for right price. car does not run but comes w/ motor 2 transmissions, new carpet still in box 2 sets of wheels and tires, new center console and few other things. I have owned 4 g-body cars love them but have the chance at a 74 nova in pristine condition can't pass that deal up and ol lady says gotta give up the cutty to get it

[curtis73]

If you want to keep the 307, it can be made to perform nicely. Of course there is no replacement for displacement, but if you're on a budget, 350 hp is a breeze. Make sure the 307 you choose is the later roller cam engine

5A heads, pocket porting
Edelbrock intake
Ditch the electronic Qjet and get an earlier one, recalibrated
Lunati roller cam (consult them for specifics)
headers

There is nothing particularly crippling about the 307 other than its displacement, but the other advice here is excellent as well. The 403 has a monster bore with a modest stroke all with the same external size. The Olds family doesn't really have typical big block/small block orientation. The Big blocks like the 400/455 have a taller deck height and different size mains compared to the small block cousins.

Big blocks will fit, but you'll have to do some minor surgery on the valve covers to clear the brake booster, and you'll have trouble getting headers to fit.