SBC production head info

[techinspector1]

"462" – Could be 3890462, 3891462, 3990462. The 462 is one of the best flowing production SBC heads. They were used between 1962-1968 on various HP versions of 302, 327, or 350 engines. They could have come with either 1.94/1.50" or 2.02/1.60" valves, had 64CC combustion chambers, DO NOT have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 65CC's. These heads have double hump casting marks.

"461" – Could be 3782461, or 3782461X. These were an excellent performance head. The regular 461 casting was used between 1964-1966 and could be found on 327 engines. They had 2.02/1.60" valves, a 64CC combustion chamber, DO NOT have accessory holes, intake port volume of 161CC's, exhaust 62CC's. These heads have double hump casting marks. The "X" castings had the same port configuration, but had larger port volumes, they DO NOT have accessory holes. The intake port on the "X" casting was 172CC's, and the exhaust port was 62CC's, valve sizing was 1.94/1.50". The "X" heads had double hump casting marks as well.

"291" – Could be 3912291, or 3917291. This is another good performance casting. They were found on 1967-1968 302, 327, or 350 engines. They could have either 1.94/1.50" or 2.02/1.60" valves, 64CC combustion chambers, DO NOT have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 65CC's. These heads have double hump casting marks.

"492" – 3991492. Another good performance head. They were found on 1970 LT-1 engines. They had 2.02/1.60" valves, 64CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 62CC's. These heads have double hump casting marks. This particular casting head was also available as an "over the counter" head from GM in straight or angle plug configurations.

"186" – 3927186. Another good performance head. They were found on 1969-1970 302 and 350 engines. They had 2.02/1.60" valves, 64CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 65CC's. These heads have double hump casting marks.

"292" – 3917292, or 340292. Both are good performance heads. The 3917292 was found on 1968 327 and 350 engines, had 1.94/1.50" valves, 64CC combustion chambers, straight plug configuration, not sure on the accessory holes, and I do not have any port volume data on these heads. These heads have double hump casting marks. The 340292 was available from GM "over the counter". This version had angle plug configuration, 2.02/1.60" valves, 64CC combustion chambers. These were known as the "Turbo" heads.

"041" – 3947041, also 3947041X. A good performance head. They were found on 1969-1970 302 and 350 engines. They had either 1.94/1.50" or 2.02/1.60" valves, 64CC combustion chambers, DO have accessory holes, I don't have port volume data for the regular 041, the 041X intake port should be 165CC's, the 041X exhaust port should be 65CC's. These heads have a single somewhat triangular shaped casting mark (slope on the upper left).

"040" – 3947040. A good performance head (I have read). Supposedly these heads came on 1968 327 truck engines. They had 1.94/1.50" valves, 64CC combustion chambers, DO NOT have accessory holes. I do not have any port volume data for these castings. These heads also had a single triangular shaped casting mark (slope on the upper left).

"187" – 3927187. Another good performance head (I think). They were found on 1969-1970 350 engines. I believe they had 1.94/1.50" valves, 64CC combustion chambers, DO have accessory holes. I do not have any data on port volumes for this casting. These heads have double hump casting marks.

"414" – 3973414. A good performance head. They were found on 1970 350 LT-1 engines. They had 2.02/1.60" valves, 64CC combustion chambers, DO have accessory holes. I do not have any port volume data for this casting. These heads have double hump casting marks.


LARGE CHAMBER PRODUCTION "ON CAR" HEADS

"487" – 3973487, OR 3973487X. The regular casting was found on the 1971-1972 350 LT-1 engines, had 1.94/1.50" valves, 76CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 65CC's. The 487X had 2.02/1.60" valves.

"441" – 3932441. This head was found on the 1969-1970 350 engines (255hp 350), it was a decent flowing large chamber head. It had 1.94/1.50" valves, 76CC combustion chambers, DO have accessory holes, intake port volume should be 161CC's, exhaust port volume should be 61CC's. Not to be confused with 3923441, which was a 1.72/1.50" valve, 327 truck head.

"624" – 462624, 426624, or 458624. The 458624 was a truck head, with 1.72/1.50 valves – non performance. The other castings were used mid 70's and up on 350 engines, they came with 1.94/1.50" or 2.02/1.60" valves, had 76CC combustion chambers, DO have accessory holes, intake port volume is 161CC's, exhaust port volume is 62CC's. These heads are made of thinner castings and are prone to cracking.

"882" – 333882. These heads were found on early-late 70's 350 and 400 engines. They had 76CC combustion chambers, 1.94/13.50" valves, DO have accessory holes, intake port volume is 160CC's, exhaust port volume is 60CC's. These heads are made of thinner castings and are prone to cracking as well. The exhaust port on these heads is rather weak in my humble opinion, and is not considered to be a good performance head. I have read some flow numbers on the internet regarding the 882's, and I have a hard time believing some of the flow numbers people are posting on these particular castings. I did extensive flow testing on several of these particular castings, and was not very impressed with their flow characteristics. The 441 or 487 are a much better large chamber head (in my humble opinion). The 882 intake port is very close to that of the 624, the exhaust side is where the 882 is weaker.


OVER THE COUNTER GM IRON HEADS

"492" – See listing above.

"3973370" – A good over the counter head. They had 64CC combustion chambers, supposedly straight or angle plug configuration. Used a set of these on all 3 of my 383 strokers, they originally came with 1.94/1.50" valves. We did some major port massaging and installed 2.02/1.60" valves, they responded very well to the modifications and worked very well. The combustion chambers were 64CC's. These were a decent iron head, with a lot of potential for performance.

"3965742" – Another over the counter GM iron head. I have no data on these particular castings, other than they were angle plug configuration.




As posted These are GM production Heads, NOT aftermarket.

[Dave Severson]

Interesting!!! On our Super Stock engine next year we are limited to a 1.94/1.50 head with no porting allowed.... So far we have a pair of 461's and a pair of 041's... Should I find more of these, or maybe a different head out of the ones you've listed...??

[southerner]

I would look for ones that have the biggest port volume and a closed chamber head.

[techinspector1]

Dave, will they let you clean up the bowls to....for instance....clean up a step under a seat? Going on southerner's suggestion, find the biggest intake port volume and if they have 2.02/1.60 valves, seat the heads for the smaller valves and blend in the seats.??????????????

[Dave Severson]

Can only clean up .125 under the seat....Not enough to even notice without a flow bench. Wissota, the sanctioning body, is really strict on the engine rules. As in many cases, there attempt at controlling the cost has led to higher costs in getting parts that will pass tech and still perform adequately. We're even giving some thought to running a Mopar, they are allowed 5 more cubic inches and the biggest advantage is the shaft rockers. With a Chevy or Ford engine we would have to run the stamped steel rockers.... I guess they have their reasons.... and they probably don't care if I agree or not. If we're going to play their game we have to play by their rules......