305HO Heads on 307

[rharris]

I believe I read on here (or maybe on a chevelle forum) that mid 80's 305HO heads(14014416) would be a big improvement on a stock 307. It's time for a carb and I'm just trying to decide if I want to swap out the heads while I'm at it. I plan on keeping the ram horn manifolds. Exhaust is 2" dual currently. Any experience with the 305HO heads on a low-hp engine?

[Warrens69GMC]

there are many benefits for the 305 head swap. Smaller chamber (58cc) hardened seats for unleaded, bigger valves (1.72 were stock 307, 1.84 for 305)

Me, personally, I would run the 416 castings on a 283 or a 307.

[rharris]

I was hoping to hear that. Thanks. I do not plan on changing the cam at this point. This is my first crack at engine work. I am mechanically inclined - I just want to start doing small things to see how they work and how much improvement it makes.

[Alex V.]

Probably better, with better gains, to up your compression ratio and valve sizes, etc. by doing 305 heads than putting a hotter cam, anyway. Chevy used the same calm cam in a lot of small blocks with substantially different horsepower outputs, getting more power by changing heads, pistons, carburetors, exhaust, etc. That is to say, the cam isn't the equivalent of a chip in a modern, computerized engine, that can open up tons more power for our truck engines with no other changes.

[Warrens69GMC]

Actually a Edelbrock 2102 or a summit cam k1102 combined with the 416 head really wake up the 307! You can even use a 80's aluminum intake with a late 70's quadrajet for a factory appearance.




Summit cam
https://www.summitracing.com/parts/sum-k1102

[68Stepbed]

http://www.superchevy.com/how-to/eng...e-performance/

Vortec heads do quite well on them, too!

[46stude]

Yeah, but here is the REAL question:

What shape is your 307 in??
Years ago I had a '68 C10 w/ a 307/powerglide. Probably the most gutless POS I've ever owned to this day. Actually ruined me on Chevy trucks for a decade. LOL.
Anyway, the motor was tired and I came across a fresh rebuilt set of 305 heads. Figured the bump in compression would help the 307 out. Wrong. It bumped the compression alright... to the point that it blew the oil past the rings and the junk smoked like a freight train running down the road, burning oil like crazy. At that point, I was done. Parked it in front of the house and sold it.

[BugzC10]

Does the intake manifold have to be changed if you switch to the 305 heads?

[68Stepbed]

Originally Posted by BugzC10

Does the intake manifold have to be changed if you switch to the 305 heads?

Depends on which heads.

[Warrens69GMC]

Originally Posted by BugzC10

Does the intake manifold have to be changed if you switch to the 305 heads?

416 (1980-1986) as posted with the OP, no they don't.

081 or similar TBI heads, you can grind the center to get the manifold to fit

vortec heads, yes you need to replace the intake manifold

[BugzC10]

Originally Posted by Warrens69GMC

416 (1980-1986) as posted with the OP, no they don't.

081 or similar TBI heads, you can grind the center to get the manifold to fit

vortec heads, yes you need to replace the intake manifold

Thanks for the clarifications