307 CHEVY HELP

[78Delta88]

The problem with Vortec heads is that they were designed for a 4 inch bore.

Personally I have never tried on 307 or 305. You could probably clay or Prussian Blue to see if valves will clear the bore wall with out contact.

The reason I mentioned 305 HO heads for the 307 is that they were designed for the smaller bore. Staying around .488 lift you still can use stock spring setup without issue of binding the spring and the the larger 1.94 intakes will still clear the bore with out modifications.

 

[bracketchev1221]

Trick flow has a small runner aluminum head. They even make double hump aluminum heads

 

[78Delta88]

Good info. Double humps would work

 

[Sweet_Johnny]

Here are my thoughts on picking a SBC:

Big Bore + Short Stroke = High Revs. Pair with Power Adders.

Small Bore + Long Stroke = TQ/Efficiency. Naturally Aspirated.

Big Bore + Long Stroke = BB Sized Power, especially TQ. Great numbers but can't rev high.

283: Low power. Bore out to 4" and have fun. 3" stroke.

302: Supercharge. Low comp, 3" stroke, 4.001" bore. Clean idle, HIGH boost, instant power.

305: Good for beginner car, 3.48" stroke 3.736 bore. Fuel economy. Go super high compression for power. Needs to withstand high revs. It takes a lot to clear 350 and max effort to clear 400 HP naturally aspirated. Ask a Sprint Racer.

307: 3.25" stroke, 3.875" bore. Same as 305 concerning performance & worthiness.

327: Turbocharge. High revs, long legs. 3.25", 4.001 bore. More cubes makes up for turbo lag. All small journal cranks were forged.

350: Duh. 3.48" stroke, 4" bore. Build for TQ or HP, peaky or not. Million options.

383: Powerhouse. 3.8" stroke, 4.005 bore. Or 3.75 x 4.030. Same as 350 but better in every way.

 

[1320chevy]

I just picked up a 307 Chevy not Olds thinking it was a 350 the guy told me it was a 350 and I looked up the casting Numbers (3970024) comes back to a 69-73 Chevy 307, either way, I want to Put it into my 81 Monte Carlo 229 v6 I know I need to replace everything but my goal on the 307 is 400hp I'm not sure if this is possible on this motor but if it is how can I achieve it while on a budget of 5k, I picked up a th350 that I'm gonna bolt to still don't know what rear end most likely an SS rear end or GN maybe ford 9 IN still not sure But my goal is to get it all going by August 2024

GM dropped the '07 because they knew that the 350 was and is a better choice. As engines go, the '07 wasn't bad except for factory soft camshafts. Even the 305 they installed in montes was a better engine for what it was intended for.
Building a 350 /383 costs pretty much the same as any smallblock home build. You can often find deals on stuff on FB marketplace. Take someone who knows with you so they can help identify good from junk. The two items that pretty much control hp are your cam and cylinder heads. There, bigger is better within limitations though. Too big and you'll have an expensive slug. A 350 and stockish differential will generally be ok under 400hp. Stay away from the 2004r units as they are good on mpg but carry a hefty price and also are very quirkish.

 

[78Delta88]

I like the 2004R but you are right. It's about $1,200 minimum to keep it becoming a claymore mine.