Hi all. First post here. I'm located in Australia.


I've asked this question on a few sites and cannot seem to get a clear picture.


Does anyone here have an original L73 (250hp) 4BBL 327 in a 1968 Impala, Chevelle, El Camino etc? I'm just trying to confirm if these engines in US vehicles have 3917290 or 3917293 heads. The engines we got here in our GMH assembled CKD Canadian RHD Chevrolet Impala and Pontiac Parisienne (and also in our 1968 HK Holden Monaro GTS 327) had 3917290 heads. All the rest of the specifications including carburettor and distributor are identical to the US L73.


If I go by the original GM Engineering documentation for Chevrolet and Chevelle they will have the 3917293 (75cc) head for just over 8.5:1 compression (rounded to 8.75:1 as per normal GM practice). With the 3917290 (69-70cc) heads the engine has to be around 9-9.2:1 (basically the same as the 1969 235hp 327 with 3927185 heads and 9:1 compression).


Any advice as to the chamber size in cc for the 290 heads? I'm going to cc a set I have here if I can, I've seen them as 68.8cc and also as 69.6cc?


Thanks in advance if anyone can help


Byron