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need help on a 1956 johnson 30 hp

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oldstickboat

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I recently bought an old 14 ft tri hull stick steer bass boat with a 1956 Johnson 30 hp engine. the previous owned has had the carb rebuilt (w receipts) and points and plug wires replaced. the engine starts and idles well. the first time I had it out it would not accelerate to full throttle but would idle all day long. I checked under the cover and found that someone had not adjusted a throttle stop on a horizontal shaft and the carb was not opening fully. after I adjusted this to open the carb the engine accelerated well. I then decided to convert to a fuel pump and non pressure fuel tank for safety (didn't seem like a good idea to have a pressurized gas bomb next to the batt. in a boat!). the pump is working fine, the engine starts and idles great and will accelerate slightly but not to full throttle nothing else has changed. did I mess something up installing the pump or could some other problem occurred ?
 
Actually the pressurized tanks are very good and reliable.---But that is my opinion.----Have you adjusted the high speed mixture needle , yes or no ?
 
(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason `to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
 
Did the previous owner replace the coils while he was in there? ALL 1956 OMC motors have bad coils unless they have already been replaced.
 
I don't know if he replaced the coils. the engine starts and idles so well I don't think that's it. ill have to check his service receipts to see if that happened.
 
oldstickboat said:
I don't know if he replaced the coils. the engine starts and idles so well I don't think that's it. ill have to check his service receipts to see if that happened.
Click to expand...

Yeah, that's what they all say. But the fact is that they will idle just fine on one cylinder. You can take a peek at the coils by removing the recoil starter, then the little cover off the flywheel. If they look like new, that's great.
 
joereeves, thanks so much for the carb tuning info .got to the lake tonight and after a couple runs, worked like a charm. the engine runs great and revs out well.
 
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