Metaldrgn

I was wondering if 305 heads would be a better choice to put on my 350 than the ones made for it becasue they have a huge 76cc chamber and the 305 has a 58cc chamber. With the 58cc 305 head it comes out to a 10.12:1 compression ratio and a 8.42:1 with the 76cc heads. The 305 heads have already been ported (fully I believe the guy I bought it from said). I am not sure, but I believe it has 1.94/1.50 valves in it too.

XChris1632X

did you already buy these heads. if now why not just spend the money and a little more and modify the heads you have. or buy some vortec heads.

Metaldrgn

oh they came with the engine. I could spend alittle more I guess. What's a good stock code for 350s and i'll port those.

bunker

I'm pretty sure its very common, I don't think you have to modify anything just bolt them up.

Stephen 87 IROC

Although they will work and the smaller combustion chamber is an easy way to bump up the compression ratio, don't expect any big performance gains. For an engine to make more power you need to get more air/fuel into it. The 305 heads will have small valves and small intake runners. You can get a die grinder and hog out the intake runners to get more volume and install bigger valves but for the cost, it would be better to just buy some aftermarket heads. Don't forget, you're trying to feed a 383 with heads designed for a 305.

Metaldrgn

yes I know that's why I will upgrade as money comes along. I will only keep the stock TPI as long as I have to. I still need subframe connectors anyhow before I compete this engine so I don't have a chance to twist or bend the frame. I will buy one of those minirams or whatever that make better power along with bigger injectors (haven't decided yet what ones I want). I am buying a good cam now so I won't have to upgrade later though. I'm just going for one that has max power at about 5500 RPMs (it's the higher average between 3000-5500 that I am looking for not top power). I've used Dynosim2003 for this.

BTW, what are camel hump heads? I've heard the name before, but don't know how they are different. The guy selling the 350 said he sold a friend some of those style heads and he isn't using them right now and might sell them to me cheap. I'm also going to keep it as a 350. The bottom end is already assembled and is working fine. Plus I would have to get the connecting rods machined if I change to ARP bolts (which would be crazy not to). Actually I was thinking it might be a good idea because I could get it balanced at the same time, but I don't know how much it would cost and I'm working on a budget.

XChris1632X

the cammel hump heads are usually pretty nice, they usually get some modifications done first and can be really nice heads. they are the older lt1 heads i believe. from the 70s.

Sitting Bull

The 305 heads will work most excellently for a street/strip car, as long as you aren't aiming any lower than mid- to high-12s. Then what Stephen said comes into play.

Camel humps don't have the front accessory holes you need on a third gen.

Chris9450

305 heads are good for bumping the compression up like someone else said. At the dragstrip I work at here in Charleston some guys have 350's with 305 heads on them. They are ported out like crazy of course, but the compression you get with those is pretty nice. If you use them just make sure you put good gas in there. Cheap gas would probably knock with that kind of compression.

Stephen 87 IROC

There's a bunch of different castings that are called camel hump or camel back. Roughly 1967 - 1970 production years. Pre 69 don't have accessory bolt holes on the ends of the heads. They could have been 1.94/1.50 or 2.02/1.60 valves. They could have pressed in or screw in rocker studs. Typical intake runners are only 164cc and cumbustion chambers are 64cc. The used small 1.5" diameter springs.

30 years ago these were the hot ticket to get but with the aftermarket choices we have now, it's not worth the money to upgrade 35 year old castings when buying something like Darts are better right out of the box.

New castings have a heavier deck surface to prevent warping. They have larger intake runners and flow more right out of the box. They already come with larger valves and screw in studs. The spring pockets for larger springs. They'll have new guides and seats. Ask a machine shop how much it would take to do all that work. Including new parts such as valves and springs, it'll cost more than a new set of complete heads.

I had some heavily worked over camel heads on my old 383 and ran high 11's with them at altitude. When I threw a rod, I never damaged the heads but I know I have at least 5 visibly bent valves.

Nitro

The 305 heads will bolt up fine if you want to go ahead and do it do it at least you'll gain some power by raising your compression ratio. Or just get some Vortec Heads

Jackal

What kind of 305 heads are they? If they're L69 or LG4 heads, I'd say go with them, they actually have 350 sized runners or so i've heard.

raul.garcia

From 85 to 86 305/350 TPIs had 9.5:1 CR, and dropped to 9.3:1 in 87.
Where does the 8.42:1 CR come from, is it an actual measurement of the 350 heads you currently have on the motor. A 1 point increase in CR is a significant increase in HP.
If I'm wrong, cut me some slack, I'm just going by the technical databases.



So is it a 350, or 383 like stephen said?

DevilsAddvocate

if ur on a budget get some vortec heads, cant beat em for the price imo

Metaldrgn

I get 8.42:1 with dynosim 2003 with the compression calculator. you enter in the cc size (being 76ccs), the gasket diameter and thickness (4.00x0.04), and finally the piston distance below the deck at TDC (being around 0.06). That's is how I got it for a 350. With the 58cc 305 heads it comes out to 10.12. I will look into vortec heads because I want to put these 305 heads on my other car which doesn't have any heads right now because I had to junk them because I ported into one of the water jackets. They were the swirl type anyhow so no big loss. Dynosim 2003 shows I can get almost 400HP from my configuration thus far, but I have to get actual head flow measurements once I am done porting them because yes I want to try again. It will be a good investment to get the carbide bits so I can do this because I am going to be porting the heads of an LT1 9C1 "police package" heads (don't know what the cc is on them and doesn't state in the books either) for my red car once I get the title for it. That will be the one that get alittle more attention right now. I'm just glad I got this 350 and everything will bolt right up.