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Old 10-15-2012, 03:25 PM
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Couple basics

Originally Posted by mustang 671 View Post
hi all , have been posting for a while as i have been finishing my 67 eleanor mustang . i have a 351w supercharged engine with a 6/71 weiand super charger , spec below .

high volume canton sump with windage tray and scraper
high volume oil pump
re-ground balanced crank
crane supercharger crank specs are -- fair to moderate ride,3pm 3.400-3.800 cruise rates at 8.5-1 max
degrees duration 226d @ .05"
degrees advertised 286d @ .05"
lobe seperation 112d
open and close intake 6d and exhaust 40d
gross lift .502"

hydraulic lifters on roller rockers
forged rods with hyperutectic pistons ( keith blacks)
edelbrock performer heads (need to find the spec but are good for a blower)
high volume engine run fuel pump
weiand 6/71 blower with 2x holley 600 vac secs carbs

what i need help on now is your opinions on what jets i should be using as a starting point in the primarys and secoundaries ?

currently i have .72 in the primary metering blocks and .78 in the secoundaries .

i have adjusted the timming to be 28d advanced with a idle of 22d advanced ,
the problem i am having is the carbs are spitting and when the engine finally runs its lumpy as hell ( i know its got a lumpy cam but its more so than it should be )

it will not idle and i have to keep the revs high ( say 1500 to 1800 ) but it is still rough at that rpm

do you have any idea on if my jets are too big ? it doesnt change when i adjust the air mix screws . they are currently out 1 turn .

i have a omex ecu and can adjust the timing very easily ,

i have got to 2 x boses ready for lambar sensors for when i get it dynoed and have also fitted 2x heat sensors in the exhaust manifold ,

but before that i just want to get it running on idle , also i cannot start it with the choke on . i have to have the flaps on the carbs open, which tells me it needs lots of air -which i have heard most supecharged engines and high lift cam engines never use the choke ??

am getting really frustrated as the car is 99% finished and i just want to get it on the road for 6 weeks or so to get some miles on it before the snow and ice come in december . then i can store it up till spring and adjust and fix any problems.

boo hoo

cheers shaun
The engine needs a lot of initial timing, and a short (relatively speaking) mechanical timing curve, or possible locked out timing. DETONATION HAS TO BE AVOIDED AT ALL COSTS! If it detonates under a load, the engine will be toast- especially w/cast pistons.

The carbs need to be boost referenced. If there's no response from the idle mixture screws the primary throttle blades are open too far. Adding initial timing can help this just don't let the total timing get too high when you add initial. You might need to go richer from baseline if the carbs are stock. Baseline jetting can be found here.

To start it give it a couple pumps of the throttle (cold) and w/the throttle CLOSED, crank it up. Do not pump the throttle while cranking, do not partially open the throttle while cranking.

Last edited by cobalt327; 10-15-2012 at 03:40 PM.
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