Everything done but low rpm at WOT. Distributor spring?

[Lou C]

You all got me to thinking so I pulled out my 1988 OMC shop manual & it looks like you should have a 750 CFM Marine Holley!

 

[kenny nunez]

Can you post a picture of your carburetor with the flame arrestor removed?
Does this boat stay in the water? If so, how clean is the bottom?

 

[Lou C]

It should have J tubes for the bowl vents if it’s a true marine carb.

 

[Scott Danforth]

It should have J tubes for the bowl vents if it’s a true marine carb.

Can you post a picture of your carburetor with the flame arrestor removed?
Does this boat stay in the water? If so, how clean is the bottom?

post #12 had the carb number

Carb is 4bbl Holly 1850-5. Numbers on the horn are 1850-5 1692

its a 600 CFM Holley Street carb with brackets for the kick-down linkage

 

[jimmbo]

From the 1980 Holley Carb Catalog

 

[VancouverBoat]

Just to see if the shaft was moving to open the Secondaries, I would place it where movement would cause it to slide down the Shaft, as the Actuator moved upwards.
Some quick scans from Prints. August 16, 1986.

Houses on the shore in you Pic are massive now..

 

[VancouverBoat]

what color are the plugs.

new isnt a color.

white, coffee, or black.

if your plugs are white, you are way way too lean.

measure the rocker arm movement with a dial indicator. your valves should be moving almost 0.550"

Plugs were just put in about 50 hrs ago but I can't check them again because I have to remove manifolds to remove plugs. I just replaced the manifolds for $6000 so I would not like to do that again. Rpms were same as before new plugs. Plugs at that time were coffee mostly. Not bad.

 

[VancouverBoat]

fuel pressure will point out the Anti-Siphon or pickup tube filter as issues if there is no fuel pressure at anything over idle.

I will put in fuel pressure gauge this weekend

 

[VancouverBoat]

You all got me to thinking so I pulled out my 1988 OMC shop manual & it looks like you should have a 750 CFM Marine Holley!

Scott mentioned that way back in posts but there was some debate that I should still get enough air and fuel. I was getting no vacuum at wot so that seemed to indicate to some that I was ok at current cfm.

 

[VancouverBoat]

Can you post a picture of your carburetor with the flame arrestor removed?
Does this boat stay in the water? If so, how clean is the bottom?

Please see pic. Bottom just hauled in may and new anti fouling

 

[Lou C]

Doesn’t look like a marine carb. No j tubes for the bowl vents & no fuel pump overflow hose…the nipple is on the flame arrestor…...

 

[jimmbo]

Doesn’t look like a marine carb. No j tubes for the bowl vents & no fuel pump overflow hose…the nipple is on the flame arrestor…...

It is not a Marine Carb, that was determined the moment the OP stated that it was a Holley 1850.

 

[jimmbo]

Please see pic. Bottom just hauled in may and new anti fouling

Two Cables going to the Throttle Lever? Has this boat got 2 Helms?

 

[kenny nunez]

I hope that your fire suppression system is in good order. If that carburetor should ever “flood over” you will have a fire. The carburetor is not Coast Guard approved. And as others have stated you need the correct one as Lou pointed out.

 

[VancouverBoat]

Two Cables going to the Throttle Lever? Has this boat got 2 Helms?

Yes

 

[VancouverBoat]

I hope that your fire suppression system is in good order. If that carburetor should ever “flood over” you will have a fire. The carburetor is not Coast Guard approved. And as others have stated you need the correct one as Lou pointed out.

Yes, understood.

 

[jimmbo]

Is there a chance that having 2 throttle controls is inhibiting the Carb from opening far enough to make power? Have you ever tried running it with just one set of controls connected?

 

[VancouverBoat]

Is there a chance that having 2 throttle controls is inhibiting the Carb from opening far enough to make power? Have you ever tried running it with just one set of controls connected?

Yes, I have tried that. I have triple checked and the throttle lever to the carb is rotating to full stop.

 

[jimmbo]

FWIW
At 100% Volumetric Efficiency a 460 cubic inch inhales 230 cubic inches per rev. so at 5000rpm it would inhale 1,150,000 cubic inches of air, which is 665.5 cubic feet. However since very few Naturally Asperated Engines can achieve 100% VE... I will be generous and allow an engine from the 70s to have a VE of 80%. So 80% of 665.5 cu ft is 532 CFM. I was also being generous as to the 5000 rpm, as I doubt OMC's WOT range was even up to 4600rpm

 

[VancouverBoat]

I hope that your fire suppression system is in good order. If that carburetor should ever “flood over” you will have a fire. The carburetor is not Coast Guard approved. And as others have stated you need the correct one as Lou pointed out.

Thanks, I think I understand now some the difference between regular and marine carbs. We must be in the wild west up here in Vancouver BC because I would bet that there are many older boats up here running with regular carbs. There probably should be regulations, but I cannot find any regulations that regulates what carb can go on a used boat. I have had tons of used boats and never knew to check if the carb was a marine version.