HPJunkie

Jim at one time you posted flow # on stock gm rect. heads and # pocket ported and matched. My brother is working on a 502 build up and is trying out desktop dyno. The program asks for them . Could post again? THenks Greg Maurer

baronmarine

greg jim's # is 616-735-0800 good luck he can make them flow

articfriends

Greg,in umtouched form these are the numbers that are published as independently flowed on westech's flow bench:
188 castings
.200-129/88
.300-188/128
.400-233/154
.500-259/172
.600-291/177
990- castings
.200-125/101
.300-183/134
.400-233/163
.500-264/180
.600-292/185
jim could answer the pocket porting question better but i would figure 10%,i would be inclined to have the exhaust ported to get flow balance close to 75 or 80 % instead of 63 or 64 % that these #'s show,Smitty

Payton

did the 188 castings come on the 454 mag?

Tinkerer

If you have him put the wedges in they will really flow.
Not as good as aftermarket but close.

articfriends

gen 5/6 454/502 mags actually came with 088 heads (according to gm performance parts book) other than water hole alignment for gen 5's and the smaller threaded holes for the non-adjustable valve train they are supposed to have identical ports and chambers to the 188's and 990's.Although looking at the flow data the 990's flow slightly better so there must be a slight casting difference somwhere,Smitty