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305 Head options?

Fabrimacator21

Fabrimacator21

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This is a boat motor so no "put a 350 in it" replies please:crazy:.

What are the options for 305 heads? Are 350 heads a straight bolt on?

Current hp right now is 185hp.... I'm looking to hit 260hp. I'm thinking with a cam, Intake, and some good heads I could get there but I don't know what heads will work. I'd like to use the Dart Iron eagles as they are cheap, good heads but do I need to look for anything specific for a 305 head? Also considering vortecs.
 
Factory "416" heads work pretty well with the smaller displacement motors . And there are s/r torquer heads available for 305's .
 
if you dont mind paying for some machine work, vortec heads can be milled down to a small enough chamber, i cant remember how much material needs to be taken off, they are 64cc from the factory, youll want like a 55cc chamber for the 305.

other than that, yeah, the 305 torquer heads are a very popular swap, the main thing is any 350 head you use, you are definatly limited to 1.94/1.50 valves, and even those are gonna be shrouded by the cylinder bore.

a stock 350 head, will lower compression considerably due to the much larger chamber, unless you have it milled, or switch do a domed piston.
 
Found this article which has me leaning towards the vortecs... http://www.popularhotrodding.com/en...s_305_chevy_engine_blocks/engine_testing.html They took .030 off the heads for a 60cc chamber. Not sure what compression ratio they had but 367 hp out of a 305 is damn impressive. I'm shooting for a certain hp at a certain rpm (280-300 at 4500 rpm) and the vortecs are just about perfect with a xm262 Marine cam according to desktop dyno.

What could I expect to pay for machine work?

What do you mean by "shrouded by the cylinder bore"?
 
dunno about machine work cost, never actually had it done, was just researching it at the time (was building a modern DZ302 with vortec heads and was trying for 11:1 compression without domed pistons. 350 block, L99 3in stroke crank and 5.94in rods, so on and so forth).

the low hp range of the 305 comes from the valve shrouding, and the long bore to stroke ratio. It was designed as a truck engine, for torque, and does that very well.

If you were to lay a gasket on the cylinder head, well, not a gasket cuz its 4.100in istead of the 4in bore, but anyway, the edge of the valves are very very close to the cylinder bore, its why you cant run 2.02/1.60 valves on a 305, there isnt room in that 3.736in bore, the valves would sit on the deck when you bolted the heads on. Having the cylinder wall that close to the valve essencially blocks the airflow on that side of the valve, and limits the volumetric efficiency of the cylinder head. however, youre looking at 4500rpm, the smaller 1.94 valve would be better anyway, as port velocity is more important for packing the cylinder than max airflow, which youd want in a 8000 rpm drag motor.
 
pauly383 said:
367 hp is cool , Car Craft built a 325hp vortec headed 305 while back http://www.goingfaster.com/spo/325_horsepower_305_cid_chevrolet.html

. Lunati built one with 343 hp , with stock 416 heads with larger 1.94 valves installed and a little bowl work .

http://www.hioutput.com/tech/343hp/343hp.html
Click to expand...

I did some readin on the '416 heads.... don't sound halfbad. The RHS vortecs flow 27 more cfm then the stock 350 vortecs though but they are 600 assembled.

Whats nice about the RHS vortecs is you don't need a vortec manifold... any carb manifold will work. So that saves some money.

I'll have to try and find some flow numbers for the '416 heads and see how they do with that cam.
 
A 1.94" valve will hit the cylinder wall if used on a 305. Also machining .030" off the head deck will totally screw with valvetrain geometry and port alignment.
 
4X4HIGH said:
A 1.94" valve will hit the cylinder wall if used on a 305. Also machining .030" off the head deck will totally screw with valvetrain geometry and port alignment.
Click to expand...


:confused: These guys did it with no problems? http://www.popularhotrodding.com/en...s_305_chevy_engine_blocks/cylinder_heads.html

I didn't see anything about valves hitting the cylinder wall. Also intake alignment seems like it should be ok since head gaskets can vary .030 without much problems. Aren't most head/intake combos off by more then .030 on the ports(mismatched) already?

Your scaring me... cause I know you know your chit.
 
If you cut .030" off a head it is already likely that the bolt holes won't even line up to the intake let alone ports not matching. Then there is the geometry problem still. :deal:
 
interesting....... id never heard of 305 vortec heads..... to google i go, i would ask the seller a question and see what chamber size those heads have. i didnt see it in the ad.
 
You could also probably make do with the early 90's RS/Z28 Camaro heads . Those motors made 230hp net ...... before you even bolt a single uprgrade to it . Thats within 20 horsepower of a Vortec truck 350 .
 
pauly383 said:
You could also probably make do with the early 90's RS/Z28 Camaro heads . Those motors made 230hp net ...... before you even bolt a single uprgrade to it . Thats within 20 horsepower of a Vortec truck 350 .
Click to expand...

I'll check it out.... I know the marine vortec head 305's are pushing 270 hp... thats with a very mild cam and a stock vortec intake.
 
And don't forget the EASY horsepower that doesn't take much effort .

Windage tray .

Roller Rockers ( all ratios actually match per set , as opposed to stamped factory ones ) .

Port match intake .
 
pauly383 said:
And don't forget the EASY horsepower that doesn't take much effort .

Windage tray .

Roller Rockers ( all ratios actually match per set , as opposed to stamped factory ones ) .

Port match intake .
Click to expand...

Port matching is a good Idea although I've heard thats only worth about 7hp... but still 7hp is 7hp.

Not sure if the roller rockers would be worth the $$$ since this thing will never see more then 4600 rpm. If money allows I may go ahead and get some but I'm not sure if I'd see any gains in my rpm range.

Also what can you do to the windage tray? I'm intrigued.:thinking:
 
Most engines do not use a windage tray. A windage tray if you don't know helps to keep engine oil away from the rotating crank. There is also a crank scraper which helps even more but are a huge PIA to install since you need to "fit" them. Oil that is allowed to get slung around by the crank is wasting HP since it becomes a resistance and anything that adds resistance takes away from HP that can be made.
 
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