hi i just picked up a rebuilt set of 516 heads ,they have 2.08 intake 1.60 exhaust,with hardened seats .the heads were milled flat about .015 .they are going on a 78 440 engine . my comp is about 8.2 to 1.the heads i have now are #4532287 older stage v heads with about 90 ccs. i was thinking about having the exhaust cut to 1.710 .i was wondering if any one knows if and how much it will increase comp,and if i leave the 1.60 valves will it greatly affect power.
comp will increase to about 9.0 , use a mrgasket thin steel gasket and get 9.3 what cam u have and carb size and exhaust is needed to know about affect of exh. valve size. about 10-25 more with the 1.740 1968+ big block valve. have the ports blended for 20 or so hp.
i have a holly 750 carb ,mopar hp exhaust, am thinking about 1.7/8 headers.the intake is a edelbrock performer idle to 5500 cam is edelbrock about 440 lift it matches up with intake. i was thinking of using a .039 head gasket i recieved a price of 45. dollars per exhaust valve to opan plus cost of valves. the exhaust is 2.5 inches. i am trying to get to about 450 horses. do you know if i will be close
450-475 Horse with these heads is realistic. Get a set of Ferraro exhaust valves 1.74", around $100 for the set. I would have the heads ported and polished, cut another .040 thous to get the comp. up around 10-1, using the thin head gaskets. You will need at least the 484/284 Mopar performance hydraulic cam. Exhaust? 1 3/4 headers will actually out perform the 1 7/8 below 5500 rpm. Good luck Doc
hi thanks for the replies how good are the stock hp exhaust manifolds.do you know if the tourqe will also go up if so about how much. at 9.6 to 1 do you have any idea of hp thanks