ted13b

I had planned to replace the L48 in my 77 with something more powerful this winter, but it's just not in the budget. I was reading posts over on nastyz28.com, and they were saying that you could put 305 heads onto the 350 to get a substantial compression increase. Has anyone tried this, and what kind of power boost can this provide? Are any 305 heads preferable over others?

Indiancreek

They are weak with thin deck surface and tend to crack. I you are planning to run them very long or hard. It's hard to find them not cracked anymore. They will raise your compression though.

Gordonm

Crappy head. Don't waste the time or effort to put them on. You will see minimal if any gains.

rcread

You can get aluminum L98 heads for pretty cheap, and they flow much better.

427Hotrod

You get compression but no airflow. Airflow beats compression any day.

JIM

curtis75

You can find Vortec 350 heads that will bump your compression a bit (64cc chamber) and the flow pretty well for a stock head. Watch your lift though they are only good to ~0.475" I believe. Don't expect them to perform like aftermarket aluminum heads but they are a better option than 305 heads for roughly the same price.

ted13b

Thanks guys, I was jsut wondering if it was a cheap way to pick up some horsepower for the summer, with a real rebuild next winter. I want to get my L48 up to 30-325 hp. I don't need a race car, but something with a little power coming off the line would be nice. It's an auto with 3:08 gears and not a race car. I'm thinking Vortec heads, up the compression, cam swap and intake. I've already done a 2 1/2 dual exhaust.

billla

The impact of compression increases, especially at builds less than 1.4 HP/CID or thereabouts, is overblown - a few percent at best...Vizard has an interesting reference on this in his books. Chase flow, not compression

The 305 on a 350 is an old trick, and really not a good one - as noted the heads have lousy flow (I saw a post somewhere where I guy put in bigger valves and ported the heck out of a set...to get them *almost* as good as a set of stock Vortecs ) and they have durability issues.

A Vortec "top" is a fairly cheap way to add power - just keep in mind you'll be swapping the intake and valve covers as well.

cv67

Those heads are crap. Couple guys on the Fbody sites want to make science projects out of them then try and convince the rest they are the cats meow dont waste your money on old door stops.

texas jim

I did the 305 head swap on an '83 Chevy pick-up that I bought f/ $250.00 from a big mechanical contractor on one of the job sites years back. I'm a crane operator f/ structuraI steel. I took the emissions off, installed a big old AVS carb w/ the manual choke, and the engine ran like heck. The 305 heads had 64cc chambers, but the valves, I believe, were smaller. I don't think the flow in either head was worth a crap, the 350 being just a run of the mill engine. Anyway, I drove the truck f/ 6 years and sold it f/ $500.00, not bad. I did that to an old work truck, and like I said, it ran quite well, but I wouldn't do it to my 'Vette. It's not THAT big of a power increase and a ghetto way of doing things. Years back, I knew a guy who did 305 heads w/ big valves and worked chambers. They were about $800.00 a set to get done, but at the time, about 20 years ago or more, they were a real running thing. Save up and invest in the AFR 195 heads, worth every penny.

As stated earlier in the topic, the power increase isn't that great, and the 305 heads are thin and once over-heated, you may have a total loss. Stay "up-town" w/ the mods on the 'Vette. LOL!

drwet

A friend of mine had a Firebird years ago with a 350 with 305 heads. The bottom end wasn't bad, but fell on its face at about 4000 rpm. Not much of a motor.

63mako

Flow numbers are under 200 CFM @ .500 lift. Best used as boat anchors or melt them down and makle a toyota out of them.

VegasJen

I did it years ago on my original worn out L-81. Wasn't a bad pick up with a mild cam. Don't think those heads are any more crappy than the other lightweight castings of the era. The mid 80s "HO" heads are the ones to get if you do. I had a mild cam around 260* duration and figure I picked up maybe 20-30hp (garage port job helped too. Not bad if you get the heads cheap, but don't think you're all of a sudden going to be terrorizing v-6 Camaros.