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'66 Carburetor Adjustment

J

Jamespio

New member
I decided to completely overhaul the fuel system this winter. I'm in reassembly now, and wondering if there are any differences in adjusting a carburetor for a marine application, as compared to doing it on a car/truck. The engine is a GM 230, inline 6. The carb is the trusty old Rochester 2 barrel. I've found some tutorials on adjusting the Rochester after a rebuild, but don't know if the differences in the fuel system mean there is any difference in the sequence or setting of carb adjustments?

If it matters, and mainly cuz I'm pretty thrilled about it, I am replacing all fuel line, new fuel-water separator, new fuel filter (it was absent), new pump (somebody put a GM car pump on), and of course bunches of new fittings, all leading to a rebuilt carb. I'm very, very happy with how it is all going so far.
 
There is no real difference in the set up.

Follow the choke set up properly, May require a small adjustment if its to rich when installed and running.

Follow spec sheet for float height and drop fro your engine.

Air/Fuel mixture screws 1 1/2 turns out from lightly seated to start with, then with engine warmed up, set main idle to ~ 650 ish rpm and fine tune air/fuel mixture screws to MAX achievable rpm. Readjust main idle back to 650 rpm if needed. (Mercruisers with Alpha type outdrives do NOT like idle over 750 rpm with regards to shifting. So the closer to 650 the better.

Note: Marine carbs do NOT have a high idle step(s) on the throttle linkage. The operator controls idle.
So when starting boat cold, a couple full pumps with throttle lever, put throttle lever at about 10:00 and start engine. Run engine during warm up at 1500 rpm or so til choke opens then return to full neutral wich should be idle rpm.

FINAL ADJUSTMENT-Once in the water and the boat is running and under load, you may need to re-adjust idle rpm so be prepared. Get away from everyone, put boat in fwd at idle location, (best if you have a second person to drive boat)
Once in gear and at idle if rpm have dropped adjust to ~ 650 ish again.
 
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