Holley 3310 jetting for 360
The carb is 3310-11. It has a block in front and plate in back. It is totally stock from Holley. The timing is about 20deg. and vacuum is around 10 in. in drive at around 900rpm. The MP electronic dist. has about 14 mech. all in around 2500rpm. I believe the factory pri. jets are 70 with a sec.plate of 134-21(whatever that is).
Mine was a -3. I don't think there were major changes between 3 and 11 but don't know that for sure.
Sec. Plate 134-21. Holley's catalogs shows that as equivalent to jet size 75 but likely it's miswritten and not right. 76 Jet is probably more like it.
Secondary metering plate vs Secondary Metering Block?
Best runs were with 74 primary jets.
However, yes the plugs would get black on the street. I beleive that was almost all due to the 'idle circuit'.
In part, this was addressed when fixing the high idle speed like you have.
We did the old school procedure (described in Urich & Fisher
Holley Carburetors and Manifolds)
Drilled small holes in the primary throttle blades close to the idle bleeds. This let the engine run with less throttle opening.
But then off-idle was too lean - the engine would want to die on any uphill.
So we decreased the idle air bleeds by sticking wires in each of the primary idle air bleeds until it ran well. Eventually I had new bleeds made and pressed them in but really there's no need. I've got two carbs now with wires in the air bleeds. Just wrap the wires so they can't move. I'll post pic if you want.
Timing. This is the tricky part for getting the carburation to work right at idle and on the street.
The Chrysler made Mopar Performance distributors are good, whether its the street unit with vac advance or the tach drive unit.
If you have the Mallory made Mopar perfmance distributor, its only OK.
I can walk you through any of them.
Initial timing with that cam and a low comp 360 should be around 16 - 18* BTC. Vacuum advance plugged.
Total mechanical (initial+ mech. adv) should be 32 - 36* between 2600 - 2800 rpm on a Chrysler built distributor.
When using vac advance in this situation, attach to ported source on the carb. Adjust it as described here:
https://www.forabodiesonly.com/mopa...mopar_performance_instruction-png.1715175314/
If using the Mallory built distributor, may have to dial in less vacuum advance because the mechanical curve is too fast.
With the timing curve closer to what the engine wants, it will be easier to cleanup the carburetion.
