650 on 355 questions
I have lots of info and questions so hopefully you enjoy the read and can give me some pointers!!!
First off, here's the motor:
350 4 bolt block decked/line-honed and bored to .030 = 355cu in
Forged crank .010/.010, Forged 1 piece oil pump drive, Melling HV pump and pick-up, ARP rods, ARP bolts, Forged Pistons, .125 pop tops
Cloyes Tru Roller Timing Set
COMP CAMS EX286C Cam .284/.480,
Vortec Heads pocket ported and bowl hawged, Dual springs: 1.94 intake valve/1.50 exhaust valve, Lift at both valves .484in, Lobe Center 109.0, Overlap 64
SpeedPro Hydraulic Lifters
Edelbrock Performer Intake
It previously had an Edelbrock 600cfm 1406 performer carb which I ousted in favor of a freshly rebuilt Holley 4777 650 Double pumper. After much screwing around I finally got it running as I had issues with floats/needles and squirters.
Now that it is on and running I've got the idle mixtures/speeds set/etc. However, I'm thinking that the builder put in jets that are too large........at least for the secondaries based on the description I'm about to give!
I took it out and it seem to cruise fine and slowly accelerate fine as well. However, a short burst of W.O.T causes it to nearly stall, hesitate, and then pick-up only AFTER I start backing off the pedal. I can't see outside to tell if its blasting black smoke under a load but it does if you floor it quick in park....... but from this description I think the second shot is choking the motor.
At idle I have around 12-13" of vacuum pressure, going up to around 20-22 if you bring it up and hold @ 2000rpm (or close, I couldn't see the tach) from the engine bay.
It was initially tuned/timed/etc to the edelbrock carb so should I advance the timing slightly to incorporate the added size of the new carb?
***Also, I do not know the size of jets or power valve that are currently in the carb either. I've emailed the builder to save myself a little time before pulling everything apart and actually checking the numbers but does anyone have any GUESS on what sizes would likely work best in this set-up???
It does have an automatic which I know are not ideal for Mech secondaries but it is geared @ 3.73 and has a 2400 stall converter.
*****THANKS IN ADVANCE for any info or direction! It'll save me having to call my mechanic friend over to mock me......and if you need more info just ask and I"ll try my best to accomodate