C-1 Fuel Injection Heads

[Ray C.]

Has anyone researched the evolution of the fuel injection heads. (C-1) I am of interest in the 1960 to 1962 heads. Reading Noland's Adams Vol. 1 pg. 293 references the use of an aluminum head # 3767467 casting #3767466. The symbol was a rectangle and the article states that there is no evidence of the heads ever being used in a Corvette other than information provided by Mr. Duntov, stating that they were used during the first three months of production and discontinued do to manufacturing problems.

The 61-62 JG list the #3782461 used during the 61-62 production cycle. The heads had three different casting symbols; rectangle, double hump with the top cut off and the round top double hump. (would appreciate pictures of each symbol)

Is there a time line for when these heads were installed on the 61-62 fuel injection engines?

Thanks for any information

Ray #36314

[Gene M.]

Re: C-1 Fuel Injection Heads

Ray, Be advised that the 461 were produced with valve pocketing for 1.72" and 1.94" intakes. The smaller heads are identical in casting features but were machined different (larger) to accodate the bigger valves. Any machine shop that prepares race engine heads can do this. If you want to maintain correct valve face positions I prefer to use the 1.72" heads and machine them for 1.94". Old 1.94" heads that had a few valve jobs will suffer from regressed position valves if maintaining the 1.94". The 2.02" is not a good choice for a 283 engine. The valve too big for bore as flow goes.

Most heads (461's) I was concern with were double camel humps from 62 to 66 dates. The 461x heads were another option in the 61-62 time period. The engine shop I dead with say the 461x have larger ports than 461's. They were the cast bar with a triangle and use 1.94" if memory is good.

[Duke W.]

Re: C-1 Fuel Injection Heads

461s were never produced with 1.72" inlet valves. A 1.72" inlet valve would fall through the pocket as cast. From 1961 to 1963 all had 1.94/1.50" valves and the size was increased to 2.02/1.50" for SHF/FI engines from '64 to '66. All 461s are "big port" heads with some bigger than others.

More to follow.

Duke

[Duke W.]

Re: C-1 Fuel Injection Heads

AFAIK the 3782461 heads were installed on all FI engine in 1961 (including the hydraulic lifter version), and they are the reason for the increase in power over the 1959 versions. The 1960 sales literature lists the higher power from the ill-fated aluminum heads, but they really were carry-over '59 engines because of the cancellation of the aluminum heads due to durability problems.

These early 461 heads were the "X" version (the "X" is under the water outlet) and have, depending on source, about 172 cc inlet ports versus about 160 on the later 462 heads. These "461X" heads were essentially a cast iron version of the ill-fated alumiunum heads.

There is also supposed to be a "non-X" 461 head that came along sometime in the 461 period, which extended to 1966 that had smaller port volume like 462s and follow-on big port heads. Their time period and utilization have always been elusive, but I don't think any were machined for the big valve set, just the 1.94/1.5" set and used on later 300 HP engines up to '66.

The "double hump over a rectangle" casting mark is the same as used on 462s and 291s. In fact, you cannot distinguish externally between 461s and 462s. The only way to know for sure is to remove the valve covers and check the casting numbers. I've seen engines with one of each on the two sides!

Duke

[Tom D.]

C1 - How about 1960 FI? - Thanks. *NM*

[GL Anderson]

Re: C1 - How about 1960 FI? - Thanks.

Here is a pic of the 1960 aluminum heads. I agree with Duke they are pretty much the same as cast iron 461 heads. There is only the large rectangle on the ends no pointer or other indicator. The casting number is 3772896 and the casting date is 6-24-59. If you need other pics I can pull them out and take some. GL

[Duke W.]

Re: C1 - How about 1960 FI? - Thanks.

The NCRS Spec. Guide lists head casting no. 3774692 as used on all 1960 engines, and this head carried over to 1961 - used on all except the 275/315 HP FI engines, which were built with (the X version) 461s.

Duke

[Mike E.]

Re: C1 - How about 1960 FI? - Thanks.

We have never been able to docuent original larger-valve heads on any 1960 fuelies. Although purported to be 315 horsepower because of the larger heads, they were in fact 290-horse, like the 59's.
Very early 61's (In the early 80's I corresponded with the owner of 61 #2, as well as another one in the first 15) and #2, an FI car, had the larger heads with the square boss, not double-hump. Later came the double-hump. (But not too much later). I don't recall the casting number on those really early heads--I have them in my files at home--might have been 461, might not.

[Ray C.]

Re: C1 - How about 1960 FI? - Thanks.

Thanks to all for the information. Is my evaluation of the 1961 315HP Fuel Injection head "symbols" correct. GM install two different head symbols on the 1961 fuel injection engines. The first was a 461 cast iron head with a rectangular symbol as found on the 1960 aluminum heads. The second would have been the 416 cast iron head with a double hump symbol with the flat top on the humps. The flat top double hump head was used into the 1962 model year and then replaced with the typical double hump head symbol.

Thanks for the help!

Ray #36314

[GL Anderson]

Re: C1 - How about 1960 FI? - Thanks.

Here is a pic of the combustion chamber side of the 60 aluminum heads to compare with the 461 or 461X heads. I don't have any 461 heads to do the comparison myself but somebody must. GL