I have a '90 RS TBI with the L03 (and crappy 58cc. swirl port heads). I have been trying to find suitable heads, because these ones are a serious handicap to the engine. I can't go to 350 heads, because the 64cc chambers would make even worse my already low 9.0:1 compresssion. I ain't got a lot of cash lying around to pay $600 or more for a new set of decent heads.

A car shop owner said he had stashed somewhere a pair of 307 heads. Would this heads fit? I think those 307 heads would improve a bit with porting, and I think I would have to change the manifold also (it was on my plans) and make a plate adapter to retain the TBI.

I have not seen the heads to check the casting number, but how many different 307 heads could be? A friend had a Chevelle with a 307 and I remember it ran really good, so I'm giving it some thought. What do you think? If not, what other heads could I look for? from a 327?

Thanks for your help...

 

Those heads probably have 64cc (or larger) chambers on them, if they are even Chevy 207's and not Olds (Olds won't work). Just get a set from a 305 TPI car and have them ported.

 

Yeah...that's what I have been finding in casting number listings... most 307 heads are shared with the 327, and have 60, 70,74 or 75cc volumes...

I don't think I can find very easily 305tpi heads either...

 

oops, just saw your location...you are going to have a tough time getting any heads for your car. You could always try E bay, but shipping is going to break you.

 

Most people wont mess with 307's.


When I bought my 69 chevy truck it had a 307 in it.The P/O told me it was a 350.


I put a comp cams 270H cam.An edelbrock Performer RPM intake,an edelbrock 1406carb,an HEI with an accell super coil.My truck also has a 3:73 and a 3 speed manual tranny.



It ran pretty good.I swear I revved it to 7-grand.I did it twice.I am not sure.I never took it to the track.It probably ran in the 15's.Which isn't bad for a motor haulling a 4 thousand plus pound truck around.That I built for around 600 dollars.

 

chevy 307's were all low perf bread and butter motors
I don't think any were offered with a factory 4 bbl carb.
All the heads from 307's are low perf low compression and small valve heads. casting #"185" is typical

To improve your 305 on a budget you should be looking for
305 HO heads ("416") or 305TPI heads. ("081") castings

Both these heads have 58cc chambers and "unrestricted ports"
Both will respond nicely to porting and larger 350 sized valves.

A 350 based HP head (64cc) such as 083's (tpi) 041's or 414 or 186 or 492 or 217's can be used with a little flat milling to reduce the chamber size to 58cc's.

Again don't waste your time or money on a 307 based head.

There is a 305 Version (58cc) (casting #" 059") of the 350 vortec head from 96+ 305 vortec truck motors that has lots of potential and should be cheap. It is simular to the 350 L-31 vortec heads with larger raised ports and requires a "vortec" manifold. the valves are smaller (1.84x1.50) and the chamber looks more like a 305TPI head than a 350 vortec head.
Will respond well to home porting and larger valves too.