MattW

iTrader: (1)

-Edelbrock Performer RPM Intake Manifold
-Holley 670CFM Street Avenger Carburetor
-Ported and Polished Vortec Heads
-XE268 Camshaft Hydraulic Flat Tappet, Advertised Duration 268/280, Lift .477/.480
-shorty headers w/y-pipe to 3" hooker catback
-3.73 gears


it has the stock jetting right now which is....primary:65 secondary:68

i have access to a jet kit and secondary spring kit and i am going to the drag strip this weekend and i was just wondering if anyone might have a similar setup and be able to give me a good starting point as to what to change the jets and springs to....i ran a 13.5 with no tuning whatsoever so hopefully i can drop off a couple more tenths if i tune it right.....thanks!

xpndbl3

iTrader: (5)

shut the car off right as you cross the traps and coast to the return road, get your slip then pull a plug and read it. black/grey is rich and white is lean. look for a brownish tan to slightly black color and adjust jetting accordingly. at the track getting as close to a "Square" jetting has gotten the best MPH for me, but yours may vary. jet up or down and launch the same way and remember to change one thing at a time to not confuse where the gains were made. don't go by ETs only mph as that is the indication of horsepower.

five7kid

iTrader: (14)

Man, if you've got a primary PV and do better at the track with square jetting, you really need to up the jetting by half the difference between the two for your street jetting. The secondaries should be 6-8 jet sizes larger than the primaries, because the primaries have the PV flow added to them when vacuum drops.

Matt, you want to drop 2 tenths? Dump that SA and get yourself a 650 double pumper. I seriously doubt you'll ever get 2 tenths out of tuning the SA. It just isn't a performance carb.

xpndbl3

iTrader: (5)

on a double pumper both the fronts and rears have power valves so isn't the flow essentially the same?

five7kid

iTrader: (14)

Most double pumpers only have a PV in the primaries.

xpndbl3

iTrader: (5)

hmmm my 850 double pumper has a power valve front and rear, as did my other 750 that I sold off last season. But I always leave the primaries leaner for the street and go up 4-6 sizes or so at the track for best times and the carb is almost square jetted each time I track it.

five7kid

iTrader: (14)

If it has a PV both primary and secondary, then jet it square. On the street, the PV will be closed for cruise, leaning it out sufficiently for non-power conditions.

That's the whole point of the PV.