I am rebuilding this car bought a car with afr 185 heads .The motor that is in it was build in 2005. The part number is #138 on one side and #1387 on the other side of the head? I typed the part #1387 in on google and got this. http://www.summitracing.com/parts/afr-1387. It says 72cc chambers? I couldn't figure out why the previous builder would have such large heads with flat top pistons? So tonight i checked the cc of the head with a syringe and alcohol and got around 58 cc- 62cc with my test. Did AFR change part # or something or do you think they are milled way down that far?