I have a set of heads number 3782461, date L121 and a 13 under the date code. What would they been used on?
Thanks

 

Used on 327's from 62-67 with a 1.94" intake valve and 1.5 vacuum. The date looks like Dec 12,1961.

 

I think he means 1.50" exhaust valve.

 

Exactly! Before this post I was reading one on vacuum...

 

Actually the nick name fuelie or camel hump #461 heads with 1.94 intake & 1.50 exhaust valves were first introduced on the 283cid - 315 hp fuel injection Corvette in 1961. This was the first year of production. They came with longer runners and was indicated with an "X" casted on the inside corner facing engine valley when mounted on engine.

rustylugnuts

 

The 461 castings were also machined for 2.02/1.60 valves (with an unshrouding cut in the chamber wall adjacent to the intake valve) from '64-'66.

 

As mentioned, the 461 series head castings were used 61-66.
The 461 castings used on 61-63 engines were the 461X castings, as seen below.





These heads ONLY came with the 1.94/1.5 valves. From a performance stand point, the X heads are slightly more desireable because they have slightly larger intake runners. BUT, remember, they ONLY came with the smaller 1.94/1.5 valves.

The 64-66 461 castings did not get the X and they had very slightly smaller intake runners. Depending on engine rating, they came with both 1.94/1.5 or 2.02/1.6 valves. The heads that were machined for the larger 2.02/1.6 valves also had the combustion chamber wall relieved adjacent to the intake valve (as pointed out by John above). As seen below, and compared to a head with the smaller 1.94/1.5 valves (this is actually before and after of 461X heads that are on the SB400 in my 56 Vette).





To achieve max flow, WITHOUT a gigonda expense on a pair of 461X heads (or even 461), the bowls and intake runners can be cleaned up and lightly smoothed (I'm NOT referring to a full port and polish).

Then, if you want to take it one step further (which I highly recommend for a cam with over a .450 lift), you can have the guide plates and screw-in studs added per below (before and after of the same head).





Finally, per the date code on your heads, they would have been used on a 62 Chevrolet product (NOT necessarily a Vette). ALLLLLLLLLLLLL 300hp/327, and higher, engines came on BOTH pass cars and Vettes. Thus, there is no way to know if a pair of bare 461 heads --------------------------------WITH 1.94/1.5 VALVES--------------- came on a pass car or a Vette. Except for 1965-6 L79 (350hp/327) engines in pass cars, ONLY Vettes got engines with 2.02/1.6 valves. And other than Vettes, only 65-66 Chevelles and 66 Novas got the L79.
LOTS and LOTS of 62-66 pass cars got 300hp/327 engines with 461(X) heads. In 65, for example, a 4dr Impala family type car with an upgrade to the 300hp engine was moderately common.

Tom Parsons

 

Thanks for the information on my heads. I have them on a L79 engine in a 67 and am going to send them to the machine shop for complete overhaul. I was thinking about trying to get some original heads but it sounds like these will work just fine if I can not find some original ones.

 

Dave,
Once the valve covers are in place, all the heads with the double hump symbol on the ends of the heads look the same. So, no one will know if you have full on ported/polished 61 heads with 2.02 valves, or stock 67 462 heads with 1.94 valves.

Tom Parsons

 

Tom as always, you are very informative and supply detailed information that not only answers the questions, but provides detailed visual aid. I'm speaking for this site, and especially the NCRS site & Restorer/Driveline magazine. A real asset to the Corvette enthusiast, very well done!

rustylugnuts

 

Tom thanks for the information. When I drive the car the valve covers will be on so I am going to take the attitude don't ask don't tell.
Dave