Author Topic: Idle mixture  (Read 5520 times)

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Offline DanB

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  • Boat Make/Model/Year: 1984 Skier
Re: Idle mixture
« Reply #15 on: October 11, 2015, 04:31:15 PM »
Yes both are marine carbs. Reman is 80319 from National Carbs. I would say I am getting very close to having it right. Almost wish I had never looked at the timing. Now I have to debate whether to do dizzy now or wait until Spring.

You have to remember that the only thing I have ever done with a 4 bbl before last week was take the flame arrester off.

Offline Midskier

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  • Boat Make/Model/Year: the ONLY '86 American Skier Volante Barefoot Skier
Re: Idle mixture
« Reply #16 on: October 12, 2015, 08:49:31 AM »
DAn B - you're fast becoming the the new carb expert - you ordered the right part # - 600cfm angled inlet (by the way the chevy carb is exactly the same except it has side inlet) I installed the same one last week on a commander ford - set base timing #8 - (did not power time) she ran 4480 rpm 44.8mph on gps with 2 men onboard , it was turn key only having to adjust the idle stop screw - 780-810 idle
in gear idle was 610-640, idle mix screws were one turn out - one pump when cold to start - all other starts were key only no throttle - up to a half an hour later -
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Offline rickturl

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  • Rick
  • Boat Make/Model/Year: American Skier Volante 1990
Re: Idle mixture
« Reply #17 on: April 25, 2020, 06:32:42 PM »
I wanted to revive this thread from 2015 because the ideas have been incredibly helpful, and because I am hoping midskier or someone else can solve my problem. I've done everything suggested in this thread so far, plus a whole lot more. In spite of that, my max speed is 32 mph and max engine rpm is 3400.

Boat: 1990 Volante with Indmar/Ford 351 engine - lake is at 5000' elevation.

Data Collected:
  • Idle set to ~750 rpm unloaded; ~650 rmp in gear
  • Idle mixture adjusted for max rpm
  • Idle timing set to 8 degrees BTDC
  • Full throttle speed ~3200-3400 rmp - boat speed ~32-34 mph GPS measured - very light boat with just the driver, ~1/3 tank of fuel, and little to no gear
  • Secondaries start to kick in ~2400 rpm - close to fully open by 3200 rpm
  • Max timing advance ~30 degrees BTDC at ~3000 rpm
Parts changed so far:
  • 80319 Holly Carb rebuilt by National Carbs - rebuilt again by me last month
  • Acme 13x11.5 Prop (similar results with the original 13x12 Acme prop)
  • Pertronix Flame Thrower II distributor
  • Flame Thrower Ignition Coil
  • MAGFORCE Marine spark plug wire set
  • NGK V-Power Spark Plug (UR4) x8
  • Sierra International Fuel Water Separating Filter
  • Edelbrock inline FUEL FILTER ELEMENT
  • Oil/Filter
  • Various secondary diaphragm springs tried - currently using 'purple'

Based on the posts in this thread, it seems I should be able to expect a top speed closer to 42 mph and a top engine RPM of ~4200. Is this a realistic expectation? At 5000'? What else should I be looking at?

Thank you all for your help.
Rick