dual springs pros/cons. tell me which ones yall perfer
12-22-2003, 09:06 PM
#23
10 Second Club
Thread Starter
Chris and 93polo. i just check on the 977 and 987 and they are very close. here are the specs
pn closed open rec installed req lift OD seat load
spring SL height with .612 lift
load
987 121@1.8 388@1.2 1.8 .500 1.43 328@1.8 IH
977 155@1.85 419@1.25 1.85 .600 1.46 318@1.9 IH
918 130@1.8 318@1.2 1.8 .600 1.055 398@1.8 IH
as you can see, even the 918 have a higher closed load then the 987. this might be why they are causeing valve float. also you will need to go .030 bigger on the heads to fit the 977s. i just called jegs about the 977s and they said that that they are only $140. thats an awfully good price. the only thing is, is that you will have to install it a bit heighter inorder to get a .612 lift cam in there. on the 977 if you install it a 1.900" you can saftly get .650 lift but the closed load will go to 133 which is still more then the 918s. now the queston is, is how heigh you can install the spring without going into the water jackets. i have seen some heads with bigger springs then these but they were welded to support the bottom because they did go through the coolant passages. does anyone know how much you can go before welding. i am strongly considering the 977 because they are so cheap. even with the machining they will be cheaper then the 921s as long as the machine shop does not have to weld them. then when i need to replace them at the end of the season i can replace them without haveing to pay another $500.
pn closed open rec installed req lift OD seat load
spring SL height with .612 lift
load
987 121@1.8 388@1.2 1.8 .500 1.43 328@1.8 IH
977 155@1.85 419@1.25 1.85 .600 1.46 318@1.9 IH
918 130@1.8 318@1.2 1.8 .600 1.055 398@1.8 IH
as you can see, even the 918 have a higher closed load then the 987. this might be why they are causeing valve float. also you will need to go .030 bigger on the heads to fit the 977s. i just called jegs about the 977s and they said that that they are only $140. thats an awfully good price. the only thing is, is that you will have to install it a bit heighter inorder to get a .612 lift cam in there. on the 977 if you install it a 1.900" you can saftly get .650 lift but the closed load will go to 133 which is still more then the 918s. now the queston is, is how heigh you can install the spring without going into the water jackets. i have seen some heads with bigger springs then these but they were welded to support the bottom because they did go through the coolant passages. does anyone know how much you can go before welding. i am strongly considering the 977 because they are so cheap. even with the machining they will be cheaper then the 921s as long as the machine shop does not have to weld them. then when i need to replace them at the end of the season i can replace them without haveing to pay another $500.
