Here is the scenario:
68 Camaro with a 350. Mild cam .442I/.465 exhaust, 224 @ .050 dur, flat tops, holley 600, Edel. Performer RPM, headers w/duals. The car previously had 461 Camel Humps on it that were mildly ported. It ran decent. The car blew a headgasket so the heads were pulled and sent to be surfaced. I told the guy he could use a set of 305 heads that I have till he gets his back. I had done this once before and was very impressed with the performance. We put the heads on his car and now it is a screamer! What gives? Should there really be that big a performance difference between these two heads? The 305 heads made a huge difference. I know that the compression ratio may have changed a little but the performance difference is incredible. The guy offered me $150 to keep the heads or an even trade (no chance) for his old heads.
Anybody have any ideas as to why these heads made such a big difference? There were no other changes made to the engine except the head swap. I would be most interested in hearing other peoples ideas.

Are you sure that they are 305 heads? 305 heads are not known to be screamers (usually did not flow that well). Have the heads been worked on? Maybe the other heads had problems and these heads just show the engine's potential cause they are good heads.

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68SS ZZ4, 4sp T-10, 12 bolt, getting painted

78Z28, 330hp vortec, TH350, 10 bolt (just finished)

[This message has been edited by 1st & 2nd GENGuy (edited 03-03-2000).]

The 305 heads are raising compression, a lot. The smaller ports and valves are increasing velocity, and pumping up low end torque. I'd guess the porting job on the 461's was less than ideal, ruining their low and midrange velocity and performance. (are u sure they're 305 heads!!!)

Yes, I am sure they are 305 heads. The intake valve is smaller than 1.94 and they have very small chambers. I think the last 3 digits of the casting # are 605 but am not sure. These heads are bone stock, not even a recent valve job. I pulled these heads off an 84 Camaro. The original 305 was pulled in favor of a 350. The 461's that the guy had were not hogged out. The only real work on them was in the exhaust bowls and the short side radius. The intakes were left alone. I have ridden in the car both before and after and there really is a very noticeable difference. Before the car would scratch both tires from a standstill and then start pulling. Now it will smoke them for a short (very short) distance. The guy does not believe me when I tell him that the heads are bone stock and from a 305.. I just may check those casting #'s to be sure. Still puzzles me.

Went and looked at the heads today after work. Casting #'s are 14014416 K304.
Any body have any ideas what these numbers represent. I think that the K304 probably means November 30, 1984. Am I correct?

Just confirms that bigger isn't always better, especially on the street.

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Hugger Orange & white 69 Camaro with supercharged 350, Tremec TKO, and 3.73 12-bolt

There's a magazine out on the newstand right now that is a compilation of engine articles from various performance magazines. I was thinking of tossing the 305 heads that my engine buider put on 'cause he said they were great heads for the street. Well, lo and behold the very last article in the mag is about the Ford and Chevy hi compression small chamber heads. It basically said
1)CHEAP- tons of them out there
2)Raises compression
3)Great torque and power up to 5000RPM
4) Flow as good as much more expensive heads up to that RPM
5)Circle track racers been using them for years
6) You can trace the diameter of outline of the size of the bore using your head gasket, then open them up a bit to the line followed by a P and P. This may lower your compression a tad depending on how much metal you take off but you will decrease the engines tendancy to detonate by removing the sharp corners where the head and bore meet.

BY the way, I'm keeping mine!

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74 Camaro
Canada, eh!

DEFINITELY 305 HEADS. BOOK LISTS THEM AS 80-86 TRUCK AND OTHER CARS.

Deffinately are the 305--My list shows (14014416 as being a 80-85...305..........HO, 58cc chambers, 1.84"/1.5" valves. http://www.camaros.net/forum/biggrin.gif Really want to make it turn on? Put some 1.94I and 1.6E in them w/a set of LANATI springs.

71 Camairo

71Camairo has the correct specs on those heads, I had considered getting a set for a 350 to raise compression (HO heads and those used on the 4/4L/267 V-8 were the only ones with 58cc, other 305 heads were 61-65ccs).

Be careful with 305 heads they crack. Most of the ones you find will be broke.

Larry, that is some rather disparaging news to the MILLIONS of people who are running 305's in their production vehicles.. Perhaps my view from this little city in Texas is limited but I have never heard of "anyone" having a problem with 305 heads cracking. Were you referring to the specific casting number that this post is talking about? Have you personally experienced a problem with the 305 heads? The set I have seem to be fine. If they crack, my friend is going to be a little irritated with me though. I better not tell him about this post.. SSShhhh. Our secret.

You can also get the 305 torquers from World Products, they have the small combustion chambers and bigger valves,thicker decks and more intake volume.