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help with 17082224

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lightning boy:
I think it will run best at 36*-38* of total timing, it may need more than that but it would be a good place to start. Set it at 38* total and see were the base timing is. If you are lucky it will be around 14* at idle. Then you can start playing with the vacuum adv. Do you have full control of both mixture screws now?

novadude:
I've got a nearly identical engine  - 396, 063 heads, factory exhaust manifolds, 204/214 @ 0.050 cam, Weiand 8123 intake, SMAB Q-jet (I think mine started as an Edelbrock 1904), TH400, 3.08 gears.  Bad quench with cast "rebuilder" pistons, un-decked block, blue 0.039 fel-pro head gaskets.   It's in a '70 Chevelle.  I can tell you what has worked for me. 

Ignition

My mechanical curve is close to yours - 36 deg at 3500 rpm, with 10 deg intital.  I run ported vacuum  with about 15 deg.  I can't guarantee it is optimal, but it seems to run well with this timing set-up.

Carburetor

Single main air bleed q-jet (like your 17082224)

UIAB = 0.067
LIAB = 0.059
IDCR = 0.052
Idle tube = 0.035
Idle bypass air = 0.086
idle screw orifice = 0.086
main air bleed = 0.046
main jet = 0.073
primary rods = 50M
secondary POE = 0.052
secondary POE well fill holes = 0.036
secondary bleed tubes = 0.033
secondary rods = DA
secondary hanger = F
air door opening (per method in cliffs book) = 1.36
accel pump nozzle = 0.026
float = 10/32
Float needle seat = 0.128

All-in-all, it runs pretty good.  Responsive, no hesitations or bogs, good economy (about 16 mpg running 70 mph on the highway).

Hope this helps!

bruno:
it does!! thx. it confirms my thoughts on the LIAB needing to be smaller.

bruno:
I think i am getting there! I was able to shrink the LIAB down to about .063”, and due to operator error in measuring, I opened up my DCR to .060”!! I didn’t notice the error right away, so i installed it back on the car, and now it doesn’t seem lean anymore. I have lost a touch of control with the mixture screws, although seating them both will definitely affect it. right now I have them set a 2 turns from seated. Idles is 800 for now, with VA connected to manifold. I think i need to limit the VA some, as I have adjusted the base timing to 12, centrifugal adds 30, and va i think adds another 15-17. I may need to adjust the centrifugal as well, or lower the base timing to 8/10.
the bog was still there, but different than before. there is very little change when covering the primaries, until they’re almost completely covered. pulling a manifold vacuum line off and the rpm’s come up about 100 rpm. I think this means i am very close, possibly a bit rich. I decided to disconnect the accel pump, and it still had a bog, although different again. I reinstalled it on the outer hole this time, and the bog is gone!! so….

1. will leaving the DCR at 060” hurt anything else?
2. the engine needs to come out again, as it developed a rear main seal leak. I’m quite positive it’s not the valve cover or manifold, as i can see them pretty clearly with a mirror. I will attempt to measure the cam better when th engine is out.
3. I guess the next step is to drive it and see how does? unfortunately there is still lots of snow here, so that will be a few weeks away.
4. thanks everyone for the help so far, I’m sure I will have more questions shortly!!

bruno:
I think the whole issue was th LIAB, just like cliff said. I may have to back up a bit and replace the DCR but will see.

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