Upgrading a 260hp 350
 

I know it's been beaten to death, but here's something I stumbled upon. I can pick up a set a 14096217 cylinder heads locally for cheap. They came off a running 270hp 350 Mag. I know these heads are the predecessor to the Vortec head. They are easily capable of making 285 to 300 horsepower, as they were on the 300 hp GM crate motors of the era. I know I need a new intake manifold with 27* center bolts and am wondering which intake to buy. Mind you, this is a budget build....because while the engine is out I will have to replace my wet transom.

Any recommendations on cam and intake would be great.

Thanks!!

Here's a cam I'm looking at.....

http://www.summitracing.com/parts/cc...make/chevrolet

I have to do more digging on the cam specs of that GM crate engine.

The 285hp engine had a cam lift of 447/447 with a 8.8-1 comp ratio

The 300hp engine had a cam lift of 435/460 with a 9.1-1 comp ratio

I really have no idea what pistons are in my engine and really won't know until I pull the heads. I'd be happy with 8.8-1, but of course the 9.1-1 would be best.

Buy that AFR composite intake manifold for the SB Chevy. It has been dynode by David Vizard and he swears by it. It made better HP and Torque # s right out of the box than any other intake manifold including the worked over intake manifolds. Plus you never ever have to worry about that intake manifold producing corrosion problems or dissimilar metals joining together.(dissimilar metals together produce corrosion over time especially in marine apps)

I would also look into bore & stroking the 350 into a 383.

The GM cast Iron Bowtie highrise intake was discontinued a few years ago. No stock left anywhere. I had sold 100's. GM's 86-95 part# is #14097494

So, a real good 86-95 application high rise Aluminum intake is Weiand's Speed Warrior:
http://www.summitracing.com/parts/wn...et?prefilter=1

the pre '86 260hp 350 heads are the same as the 270 horse 350mag post '86 except for the angle of the middle 2 intake bolt holes. You won't see any difference just switching those heads. They are the predecessor to the vortecs in that they came before them, but that is where the similarities end.

I think my heads are 76cc heads, not 64cc heads like the ones I'm looking at. I will pull a valve cover to be sure, but I'm 85% sure I have 76cc chambers on my engine.

Okay, the carbed '87-'95 350mag (and also the 5.7 260) had 76cc heads with center bolt valve covers and the more vertical center intake bolts. They were of the same performance as the pre 86 heads with perimeter valve covers and traditional intake pattern.

In '95 they had a TBI 350 mag, I assume these had the 64cc TBI heads, are these the ones you have? Aside from the compression bump I don't think you will gain much.

^^ The 64cc combustion chamber heads are what I will be picking up^^

They are an iron copy of the L-98 TPI heads that came on the Vettes and some Irocs.

http://www.gmpartsdirect.com/perform...CATID=671.html

Sorry wasn't trying to make it confusing.

If you don't have heads or an intake right now, go with 64cc VORTEC heads with a vortec style intake gm marine intake (or edelbrock rpm or rpm air gap). You will be much happier with the performance.