M-6049-N351. Bare Head (64cc Chamber). For use in NASCAR Late Model Stock, I.M.C.A., D.I.R.T., and most other stock car sanctioning groups on 351W engines. Much improved air flow over previous E351 heads. Machined for 2.02" intake and 1.60" exhaust valve diameters. Intake and exhaust valves have been moved .070" to unshroud the intake valve. Valve angle changed from 20 degrees to 10 degrees to further improve air flow. Intake port volume 195cc, exhaust port volume 78cc nominal. Accepts stud girdle M-6569-C351. Thick deck and reinforced structure for improved sealing, increased section thickness in critical areas and webbed rocker bosses for improved strength. Designed for stud mount rocker arms. Compatible with stock and Ford Racing intakes. These heads use Motorcraft AF or AFS-series spark plugs depending on application. NOTES: specs & photos can vary