I dont know but last week i did the initial start up on my 351/w a zcam, winsor sr. heads milled to 60cc, performer rpm matched to a 1250, 30#, crane energisers 1.6 had car down for 9 months had problems starting but after tweeking car fired and i came 4 times in 1 min. Joking but it sounded like the best mustang i ever heard. Probably cause its the first motor i built myself. Pics go to redhorse-racing.com/4 wheels and engine/ muscle car/ toms engine build someone make a hyperlink please