im running the holly 850's on my 540's, and i've had to rejet and upgrade the accel pumps and such and they still wont idle worth a damn, i have to set the idle speed up to 1250 just to keep them running at the ramp or they want to quit at the worst possible second. im ready to toss them in the s**t
can...

I have Holley 1050 Dominators worked by Nickerson on my 540's. 94's at all corners. They came back perfect. Very little transom soot and I idle a fair amount. Plug readings were spot on.

Any future carb work I may need done, they are going to Dean.

Mark,
Yes the earlier models I heard have had leakage problems. All the covers I have used, I love them! Especially if your running a mech. roller cam setup they make life quick and easy for valve adjustment checking. They work well for us.

Your problem may lie in adjustments. If you have a 4 corner idle, make sure the primary and secondary throttle plates are open the same amount. Also Idle mixture screws on all 4 need to be out the equal amount of turns, 1 1/2 turns out will get you started but every engine will require different settings. If one throttle plate is open too far you will enter the transfer slot of the carb and find yourself fighting idle issues.

Exactly as mr hp stated.

Also, if you have big cams then the throttle blades may not allow enough airflow thru, in which case you may have to drill small holes in blades to get required airflow thru.

However, make sure, as stated, that you are using the secondary throttle blade adjustment screw too to open secondaries proper amt. Most marine engine's will idle fine doing this.

Hey Dean ..... in the pics of the your motors there is a water line that comes from the rear of the motor (starboard side of carb) to the water line from the thermostat housing .....Is that a equalizing line for pressure and hot spots ? do you run a thermostat ? ....m

Do you happen to know what the elevation is where you boat at?

Did holley discontinue the 830 marine version carb? I don't see it on their website anymore.

hey I have a 1989 Doral Phazar which had a 454 Mag witch had 365 Horse power. The guy we bought it from just got it rebuilt. He said he got it Bored and Stroked to a 502 and balanced. He says it has a 850 cfm Holley carb on it and has the factory heads on it. It sounds great and everything so the heads should be fine. Does anyone think they might be able to just take a guess if they absolutely had to just around were the horsepower might be around. I was thinking 450 to 550 but I wanted someone Else's opinion. If it helps the boat is 22 ft 5 inches weighs 3650 pounds and revs at 5800- 6000 rpm with a 23'' pitch mirage prop 3 blade and we need a new prop so its reving at 5200- 5300 at most 73 - 76 mph.

that is one of the nicest rigged engine compartments i have ever seen