FireDemonSiC

Hey guys. I'm interested in getting a good set of cylinder heads for my 305.

I want a set that will flow good with my TPI setup. 52MM throttlebody, SLP runner with port matched plenum and Lingenfelter manifold.

Now I know there are certain rules to 305 heads, like don't go over 1.94/1.50 valves. But what do you guys recommend as far as intake runner size and combustion chamber size go? I really haven't delved into the cylinder head category yet so I need as much advice as I can get.

And so help me god the first person to suggest building a 350 instead gets a cleveland steamer.

SeanW

Best thing you can do is port your stock heads. Because of shrouding caused by the small cylinders reducing valve to cylinder wall clearance you aren't going to get all that much out of a set of aftermarket heads. As well most aftermarket heads will require machining to bring the chamber size back down to the 305 size otherwise you will lose compression and could end up making even less power.

You can actually make good power with the stock heads ported. Its even been a popular swap in the past to put 305 heads on a bigger small block to pick up the compression from the small chambers.

FireDemonSiC

I was told not to go over 64cc on the chamber size.

basiccamaro

Look for a set of 059 casting 305/5.0L Vortecs, already 58cc's and off of a 305 originally as well. Almost identical to the 062 64cc 350/5.7L Vortecs except most of the combustion chamber heart shape is lost due to the smaller chamber.

They only made them for a couple of years in trucks and maybe astro vans.

Damon

Stock 305 heads have 58cc chambers so anything larger than that and you're dropping compression ratio vs. stock (which ain't all that high to begin with).

TrickFlow makes a 305-specific performance 305 cylinder head that is a bolt-on upgrade. Edelbrock makes heads that will bolt on but are really made for 4" bore engines like a 350 (2.02/1.60 valves).

Vortec heads and not bolt-ons because the bolt patters to the intake is different (requiring a different intake manifold) and also because they don't have an exhaust crossover port.

Vette/ZZ4 heads have the right ports and bolt pattern for an 86 or earlier intake but still lack an exhaust crossover passage to keep your EGR system functional.

FireDemonSiC

I actually got fairly excited when I saw these:

http://www.summitracing.com/parts/TFS-30300002/