Who has already tried

[pencero]

Who has already tried running a 307 bored .030 or .040 over to 327 and what were your results

 

[85 Cutlass Brougham]

307 Chevy or Olds? A .030 or .040 overbore of a Chevy 307 will not yield a 327. The 307 has a 3.875 in bore and a 3.25 in stroke while a 327 has a 4 in bore and a 3.25 in stroke, so you would need to go .125 over to make it a 327. As for an Olds, I do not know what you would need to do to make it a 327, but I would assume it is not possible to reach a good bore size with the stock block. You would be better off finding a Olds 350 than trying to make a bigger engine out of your 307.

 

[midwestls]

x2, start with a 350. Chevy, Olds, Pontiac, or Buick start with a 350. You'll be happy you did.

 

[joe_padavano]

Who has already tried running a 307 bored .030 or .040 over to 327 and what were your results

This is why you should have stayed awake in math class. Stock bore for a 307 Olds is 3.800". With a stroke of 3.385" and an 0.040" overbore (which I also think is not possible in that thinwall block) you get a whopping 313 cu in.

 

[Minion1186]

at about 69k the previous owner of my cutlass took the 307 olds and had it rebuilt,bored .40 over and ported the heads mildly.since it has bad gears theres not a significant amount of performance diiference,also since it retains all the emissions junk except the air pump.I would say with all the performance mods it would be about at the same horsepower rating as a 307 HO,I have yet to put it on a dyno to know for sure,but definitly go with a 350 or any bigger engine than just moding a 307,its just not worth it