View Full Version : 305 heads over 350 block


ace4z28
01-25-2008, 01:58:57 AM
Purchase an 1980 3/4 ton chevy truck, after checking casting numbers found it had 305 heads (1.84/1.50-58cc) on a 350 block (#14010207-4bolt). Do not know what to do. Want to upgrade cam/ lifters/ rocker arms to roller. Want good proformance HELP!!


Casting number #14014416 &14014418 on heads

77RS
01-25-2008, 05:01:00 AM
Just curious... what is the casting number on the heads? Are those the swirl port heads?

Welcome to NastyZ28!

ace4z28
01-25-2008, 10:45:29 PM
The casting numbers on the 305 heads are 14014416 &14014418, with 58 cc chambers

-=79z28=-
01-25-2008, 11:54:59 PM
same thing i am doing on my car, it has a 305 in it and i'm going to use the 58cc heads, but you have to get four relief flat top pistons for pump gas compression (10.1:1-10.3:1), or go with dish tops that will get you into the low 9's (9.2 to 9.5 to 1), i've done some research because of this already and with a comp 280H cam, the 305 heads (ported), and 10.25:1 compression, edelbrock performer dual-plane intake, 750 cfm (quadrajet), and long-tube headers, it was making an estimated 375 hp at 5000, and 425 ft. lbs. of torque at 3500, is this the performance you were looking for?

pdq67
01-26-2008, 12:40:02 AM
-416 heads are good one's that should have squared off chambers like smog heads whereas the -601's are like the double quench, closed chambered heads, the early -461 "Fuelie" heads of old!!

I have both the -601's and the -461's out in the garage.

pdq67

-=79z28=-
01-26-2008, 11:37:58 PM
awesome! i have a set of 601's on my 86 chevy c-10, but, its a 305, its a pretty powerful one after getting the block decked, must have added a little more compression and a crane 256H cam

pdq67
01-27-2008, 01:17:29 AM
Imho, the old 305HO, -601's are VERY good small engine heads, but you have to CC them to know for sure what your CR will end up at.

Suckers can be down to 52 cc's and probably up to 58!!

CC them so you will know for sure!!

1.84"/1.50" valves, hardened seats, an eff. double quench closed chamber and 160 cc ports!!

GOOD HEADS by me!!

My pair cc'd at 53 and 55.......

pdq67

Cataldo
01-27-2008, 04:50:24 AM
So how are thoughs 305 heads? i have a pair off of a '79 305.

77RS
01-27-2008, 12:22:31 PM
same thing i am doing on my car, it has a 305 in it and i'm going to use the 58cc heads, but you have to get four relief flat top pistons for pump gas compression (10.1:1-10.3:1), or go with dish tops that will get you into the low 9's (9.2 to 9.5 to 1), i've done some research because of this already and with a comp 280H cam, the 305 heads (ported), and 10.25:1 compression, edelbrock performer dual-plane intake, 750 cfm (quadrajet), and long-tube headers, it was making an estimated 375 hp at 5000, and 425 ft. lbs. of torque at 3500, is this the performance you were looking for?

Where did you find pistons to fit the 305 (3.736") bore?

mJolnir
01-27-2008, 01:17:03 PM
Where did you find pistons to fit the 305 (3.736") bore?
summit

flyboy367
01-27-2008, 02:07:46 PM
i have a truck lower end with performer rpm cam and intake along with some mild ported 305 58cc heads. its a torquy littl ebastard up to around 4800. was gonna add tpi for more tq but may have just blown it up lol.

-=79z28=-
01-28-2008, 12:25:24 PM
i'll clarify that, its a 350 with 305 heads, sorry for the confusion

80'427
01-28-2008, 01:22:35 PM
The only problem I have ever heard is the head gasket comes super close to hanging into the spark plug cooling holes on the head surface.

-=79z28=-
01-28-2008, 01:50:22 PM
spark plug cooling holes? what are those?

80'427
01-28-2008, 03:46:41 PM
I didn't know what to call them the coolant passages that rap around the outter edge of the head by the spark plugs. I am sure they don't cool the plugs but thats the location. cresent shaped.

ace4z28
01-29-2008, 12:43:43 AM
edelbrock crabs 1406-600cfm/ edelbrock EPS intake manifold 2701/ long tube headers 1-1/2 tube, collector tube 3"/ 2-1/2 x pipe exhaust system/ Accel soild core wires. Was planing on staying with edelbrock cam lifters set/upgrading to roller system. I been told to go with 305 head gaskets to match up water jacks.

gibbyzracing
01-29-2008, 02:47:53 AM
good set of heads to build

80'427
01-29-2008, 10:08:06 AM
what the bore on a 305 gasket I thought it over hung the cylinder bore.

chopped79
01-29-2008, 11:17:50 AM
First off the 601 casting would be the only 305 casting I would ever think ov useing on a 350. That said it would be for a low rpm/high torque combo only. Even with a full port,1.94/1.5 valves, chamber relieved to unshroud the valves these heads choke the average street 350 at 4800/5000 rpms.
Years ago (late80's/mid90's) the local oval track guys went nuts over these heads due to the small chambers and what looked like decent ports. They all assumed that since the port entrance looked like a old pre emission head and that the claimed port volume was 160cc's that it was ok. Truth is the ports are choked in the short turn area way more than a smogger 350 head is, the port was designed for a small ci app. There is not enough material to open the short turn area of the port up to make it work above 5000 rpms on a larger engine, Yes it will turn more than 5000 rpms just not making any extra power beyond that point.
As for the head gasket, no way you should use a 305 gasket on a 4"bore!

pdq67
01-30-2008, 09:56:01 PM
chopped79,

I flat don't know about this, but looking back at the old PP heads that are used on the hi-po 283's and also the lower hp, 327's, I just can't see how a -601 head w/ a 160 cc intake port can choke down a 350 when the old PP heads still did pretty darn good on the 327 engines??

Heck, the PP heads are only like 137 to say, 140 cc intake port size w/ low floors or is that roof's, I always get them turned around?

And fwiw, my early '56, 265, -306 trough sparkplug head's are only 118 to 120 cc intake port sized so that's why the PP heads flat turned a 283 on back then............... I cc'd them..

Just trying to learn here and I've asked "trmnatr" from Big Brother, (i.e., Team Chevelle), to get in here so hopefully he will show up in a bit.

He's MUCH, MUCH moreso than me a small motor and head guy is all........

Please don't take offense b/c I wanna know as much about this as I can learn..

pdq67

chopped79
01-31-2008, 12:57:39 PM
It's simple, the runner cross section just before the short turn radius into the bowl seat area creates a bottle neck to the airflow when used on a larger bore and longer stroke.
It is also known a port saturation, Think of it like a pipe of a set dia, when you attempt to push or draw air through it at low volume low pressure(small bore/short stroke) it flows through easy. Crank up the flow and the volume the air path is now restricted and resist's the extra airs passage.
The 601's I have seen have never had a 160 cc intake runner, the average has been 150ish range. And the exh port is poorly designed.
You can not base heads performance on a 350 by how it acted on a 327 or a 283. Both are short stroke and one is a tiny bore set up and they both run decent with a way smaller head than a 350 and up engine will. You really can't base any parts for a 350 on what a 327 or smaller engine likes. Just as you can't base parts for a 400 from what a 350 likes. A properly built hi compression naturaly aspirated 406 sb can make more HP and Torque than a 327 can with a 671 blower!
Just because its a SB to a SB comparison it's not always apples to apples.

I have in the past worked with many 355 flat top solid lifter combos on the dyno for the oval track guys around here. The 305 heads even ported never made even the same power as a double hump did even with more compression. Reason being is they all stopped making power by 5k no matter what valve size, port work or cam was used. The 305 heads just don't move enough air for a larger ci engine to breath regaurdless of the claimed port size.

ace4z28
02-01-2008, 12:10:54 AM
Thanks guys, you have convince me to search for a pair of 350 non-smogg heads hear in the dallas area. Should I go junk yard and rebuilt them from bare or should I buy complete. I'm on a budget and would like to be smart. I'm looking to put together a daily and highway driver, but have a smile on my face if challenge at a red light. So with edelbrock crab 1406/ intake 2701/ long tube headers and 2-1/2 Xpipe system, what size cam should i go, should I stay all edelbrock and should I go roller system? I will also search for these vortec 906/602's

-=79z28=-
02-01-2008, 07:01:30 AM
craigslist is great for that, or junkyards. i'll chime in later after i get to school about what you should go with.

pdq67
02-01-2008, 05:18:02 PM
Find a good pair of either medium or big valve double-hump heads and go.

Shouldn't be worth all that much money????

And I would also use shim headgaskets too!

pdq67