Priobe What are you looking for??? Race motor, street motor, something in the middle?? Lets start with about how much HP and torque are you wanting?? What are you going to do with the car? Show and shine, 1/4 drag race, Roadracing, Street driving, Autocross, High speed mile races?? The best thing a can tell you without more info is STROKER your motor to a 452 or better 482. Barry R sells a great stroker kit that is almost a straight drop in. A 10.5 compression with your heads. Sell the Nascar parts. The cam you have is too big for your motor and the low compression you are running. IMO you are not running enought
oil pressure. I don't know what the clearances are on the mains and rods but there are only a couple of sizes available for nascar rods. You maybe able to use cleveland or windsor bearings with some machine work to the rods. IMO I would be running a 100 lb spring in the
oil pump. Limiters to the rockers in the .070-.090" oriface range. If you have 25% leakdown you need to find out where all that air is going to. Piston rings not sealing, cylinder bores out of round, Valves not sealing in the heads to valve seats. You should find out this problem first before rebuilding the motor. Has this block been bored or is it a standard bore?? If you are running 48mm webers, the flow runs out at about 6,700 rpm with a 427 motor. It will be a little less with a stroker. If you put the right parts together for a certain rpm range you will get morepower and a better running motor. Match the parts. Exhaust, you can be loosing 20-50HP in this alone. Something to look into. Need answer for the first 4 questions before trying to give you info on a motor that would best work. Ps. Preoiler for your car. Accusump works great as a peroiler before starting the motor everytime. 80% of wear on a motors bearings are from startup. IMO I would also go to the ERSON full roller rocker setup. Have you any thought on an Aluminium block? Another 80 lbs off the front of the car would be nice. You could also run a hydro roller cam and lifters and have less maintainance. KCR sells some go cams for FI and webers. I have one for my 498 motor and 58mm TWMs. Talk to Keith about what he would recommend. May sure your machinist knows the different between FE motors with it's needs and wants and chevy motors.
The days of the .003" on rods and mains are gone due to the changes in
oil.
IMO Rick L.