zac_F71
Well-Known Member
Well it seems like it's been a few months, but probably only a couple weeks LOL. my 383 build is done, and we dyno'd it yesterday. Sadly I didn't take any of the print outs, but do remember some numbers...
Did 8 pulls or so started with 69/75 jetting and 35* total, and ended up with 74/80 and 41* total and a 1/2" 4 hole spacer -all with a 6.5 power valve. Rev'd to 6,100rpm on a few of the pulls, tried 6,200 and it didn't like it. It will be a ton of fun on the street, and we don't plan ot rev it much past 5,500rpm even though it makes power to 5,800/5,900rpm, tried a few different carb spacers as well - 1" 4 hole, 1" open, and a 1/2" 4 hole. Funny part is it made good power with no spacer. It seemed to like the added timing - we tried 42* or 43*, and lost 10hp or so. So we backed it down to 41* and power came back.
Took a couple hours to get the thing running if I'm honest haha we ran into spark delivery problems, tore the distributor apart, put a new pick up in, and tried a new cap and rotor, and then it finally came to life. Found the rear main seal holder leaking a bit of oil, so we fixed that after unbolting it from the dyno..
My CPPA 2" under chassis headers didn't end up fitting the dyno bell housing (Lakewood scatter shield), so we used the dyno's 2" fenderwell headers.. here is the combo -
71 HP 383 0 decked
Stock steel crank
Stock rods with ARP bolts
KB400 5cc dome hyper pistons (.030")
Balanced rotating assembly
?Mahle? rings gapped for nitrous (doesn't have it - didn't try it on the dyno)
Trickflow timing chain (Summit Racing brand)
Comp Cams hyd 231* @.050" (280* adv) int/ex .480" 110* LSA - grind number CRB 280H-10 - degree'd in at 110*
Smith Brothers custom length pushrods
Crane Cams Gold 1.6 roller rockers *(.512" valve lift)
440 source stealth heads, milled enough to be flat (few thousandths), and professionally ported by a local guy, Comp Cams SS valves, springs, locks, and retainers
Unported Edelbrock Performer RPM that was angle milled to match the block/heads
Demon 750 speed demon carb (no choke)- rebuilt mostly stock, added rear jet extensions, and .120" needle and seats
The results? 460hp 450ft/lbs both around 5,500rpm
I will edit this and add the video's today - we have about 10 or so to go through, plus a bunch of pics
going in my 71 Demon -
Did 8 pulls or so started with 69/75 jetting and 35* total, and ended up with 74/80 and 41* total and a 1/2" 4 hole spacer -all with a 6.5 power valve. Rev'd to 6,100rpm on a few of the pulls, tried 6,200 and it didn't like it. It will be a ton of fun on the street, and we don't plan ot rev it much past 5,500rpm even though it makes power to 5,800/5,900rpm, tried a few different carb spacers as well - 1" 4 hole, 1" open, and a 1/2" 4 hole. Funny part is it made good power with no spacer. It seemed to like the added timing - we tried 42* or 43*, and lost 10hp or so. So we backed it down to 41* and power came back.
Took a couple hours to get the thing running if I'm honest haha we ran into spark delivery problems, tore the distributor apart, put a new pick up in, and tried a new cap and rotor, and then it finally came to life. Found the rear main seal holder leaking a bit of oil, so we fixed that after unbolting it from the dyno..
My CPPA 2" under chassis headers didn't end up fitting the dyno bell housing (Lakewood scatter shield), so we used the dyno's 2" fenderwell headers.. here is the combo -
71 HP 383 0 decked
Stock steel crank
Stock rods with ARP bolts
KB400 5cc dome hyper pistons (.030")
Balanced rotating assembly
?Mahle? rings gapped for nitrous (doesn't have it - didn't try it on the dyno)
Trickflow timing chain (Summit Racing brand)
Comp Cams hyd 231* @.050" (280* adv) int/ex .480" 110* LSA - grind number CRB 280H-10 - degree'd in at 110*
Smith Brothers custom length pushrods
Crane Cams Gold 1.6 roller rockers *(.512" valve lift)
440 source stealth heads, milled enough to be flat (few thousandths), and professionally ported by a local guy, Comp Cams SS valves, springs, locks, and retainers
Unported Edelbrock Performer RPM that was angle milled to match the block/heads
Demon 750 speed demon carb (no choke)- rebuilt mostly stock, added rear jet extensions, and .120" needle and seats
The results? 460hp 450ft/lbs both around 5,500rpm
I will edit this and add the video's today - we have about 10 or so to go through, plus a bunch of pics
going in my 71 Demon -
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