63StingRay327

So hear is another question for C2 Corvette Experts. I have a set of heads that are to be for a 340 HP 327 Motor. I have received mixed information about these heads. The heads I have are 461X heads. Production dated November 1962. To me these heads should be for the 340 HP motor. I have been told that the 461X are only for the 360 Fuel Injection motor. The right heads for all other 327 motors for 63 Vettes are the 461 with NO X. Can you help me on this question?

THANKS!

rick charles

THEY WHERE ALSO USED ON 327/340 hp ENGINES WITHOUT QUESTION .............................. RICK

63StingRay327

Did the 340 ever come with the straight 461 or did they always have the 461X?

69ttop502

As usual, Tom has nailed it!

rustylugnuts

Didn't the 461X heads have longer runners compared to the 461"s and were first introduced with the 283 FI option for 1961?

rustylugnuts

69ttop502

From my research the "X" heads had slightly (8cc) or so larger runners although I have never seen a definitive measurement as such. I certainly defer to Tom if he has any knowledge on the subject.

Bill

DZAUTO

The "X" heads do have SLIGHTLY larger intake runners (larger, not longer) than the 64-later 461 heads.
Sooooo, does it seem strange that 461X heads have larger runners but only have 1.94 valves, whereas the 461 heads have slightly smaller runners, but came with 2.02 valves? Well, when you think about it, no, not necessarily. With a slightly smaller intake runner combined with the larger 2.02 intake valve, IT WOULD SEEM (theoretically) that velocity would be greater in the slightly smaller runner. Maybe so, maybe no. Thus, with improved flow around the larger 2.02 valve and the machined relieving around the intake valve, air flow into the combustion chamber would be greater (on 461 heads with 2.02 valves).
Now, with that thought in mind, WAY, WAY, WAY back when, long before today's GM heads and the aftermarket heads (Edlebrock, DART, etc) with improved intake runners (and let's not forget the LS-later heads/runners), the PRIMARY method of improving and increasing flow into the cylinder was to have 461-462 style heads ported and polished--------------------WHICH STILL WORKS TODAY!!!! The only downfall to porting and polishing the early heads is someone (ie shadetree "expert" head porter) removing metal in areas which DECREASE flow characteristics. Because of the greatly improved casting of the runners in heads today, there is not as much porting /polishing done now as there used to be. At one time in the past, the really knowledgeable head porters did LOTS of flow bench testing on their porting and there have been lots of articles (many years in the past) written about how/where and how not/where not to remove metal in the runners and bowls. When properly ported/polished by a VERY EXPERIENCED head porter (translate old timer today), these old heads will still produce VERY IMPRESSIVE results in power increases. The machine shop that I use now no longer has a REALLY GOOD, KNOWLEDGEABLE head man.

Yes, the introduction of the 461X heads was on the 1961 283 FI engines. PERIOD. NOTHING else in 61 got those heads. Also, with the introduction of the 461X heads, they got the first ever HUGE valves (remember, we're talking 1961), 1.94/1.5. Up until then, the biggest valves were 1.72/1.5.
Since these heads (they had the double hump symbols) were ONLY, ONLY, ONLY on 61 FI Vette engines, take a guess where the now common term "fuelie heads" came from! And, with the fuelie head term associated with the double hump symbol, it stuck. And now, ALL the NON-knowledgeable persons refer to heads with the double hump symbols as "fuelie heads"!!! In 1961, that would have been a correct terminology, but not any more. Nevertheless, it stuck. Beginning with the 62 model (INCLUDING PASS CARS), all the optional engines got double hump heads. That's right, grandma's 62 4dr Chevy with the optional 300hp/327 and Powerglide had double hump heads. Why would grandma's 62 Chevy have come with the 300hp engine? Well, maybe it had factory air cond and needed a little more pep. Oh ya, and that brings up another issue. The 2 1/2in exhaust manifolds are NOT Corvette specific! The 62-65 Pass cars with the 300hp/327 got 2 1/2in ex manifolds. Want to guess how many thousands of those cars were built?

fastfreddie63

That is some good reading, thank you!

Those photo's really dot the "i's" and cross the "t's".

rustylugnuts

Not only received a good answer, buuuuuuuuuuuuut really enjoyed the animated overtones that made an enjoyable read..... Well done Tom!

rustylugnuts