New 2nd Gen owners...
#11
02-03-2009, 01:22 PM
50mm tb good for 318 but basic 390 better to have a 53mm. Better to pass till you stroke it.
Intake manifold, may want to cut the runners back and remove the divider to help the 390 breath. It will help the current 318 as well and can be done yourself. Should be a DIY write up about it here. Even if you dont do that, you may need to get the Hughes plenum/gasket kit cause they are very prone to leaking. (alum/steel have different expansion rates).
1.7rr would be good on the 318 and if you leave the stock cam in for the 390. For the 390 going to say krc206 cam (4x4/rv grind) be better with 1.6rr. I dont recommend the 1.7rr on any cam with over 500 lift (.512 on exh side with 206)
Head cracks are common with aged Magnum engines, when torn apart to stroke you may have to replace them. Go to Hughes & get a set of bare HD heads and resuse current valve train except the rockers.(see above). May find the same heads on ebay listed as EQ heads for cheaper. Would be better getting the 202 versions Hughes sells for the 390 but the smaller stock valved ones will work/help regardless.
As far as the superchips dyno results posted above, they are either a misprint or a outright lie from Superchips. No way a stock or near stock gasser will see that HUGE gain from a generic tune. As mentioned, it will not support the stroker so would be a waste. The SCT costs more but will grow and give much better results.
Lots to think about when you plan to stroke a motor and not worth the time, money and effort to add parts that wont be useable later. Been there, done that
Intake manifold, may want to cut the runners back and remove the divider to help the 390 breath. It will help the current 318 as well and can be done yourself. Should be a DIY write up about it here. Even if you dont do that, you may need to get the Hughes plenum/gasket kit cause they are very prone to leaking. (alum/steel have different expansion rates).
1.7rr would be good on the 318 and if you leave the stock cam in for the 390. For the 390 going to say krc206 cam (4x4/rv grind) be better with 1.6rr. I dont recommend the 1.7rr on any cam with over 500 lift (.512 on exh side with 206)
Head cracks are common with aged Magnum engines, when torn apart to stroke you may have to replace them. Go to Hughes & get a set of bare HD heads and resuse current valve train except the rockers.(see above). May find the same heads on ebay listed as EQ heads for cheaper. Would be better getting the 202 versions Hughes sells for the 390 but the smaller stock valved ones will work/help regardless.
As far as the superchips dyno results posted above, they are either a misprint or a outright lie from Superchips. No way a stock or near stock gasser will see that HUGE gain from a generic tune. As mentioned, it will not support the stroker so would be a waste. The SCT costs more but will grow and give much better results.
Lots to think about when you plan to stroke a motor and not worth the time, money and effort to add parts that wont be useable later. Been there, done that
