Carb problems still

"Jeff:

are you referring to

"Jeff:

are you referring to a MITYVAC? if so, which one of their items? After reading your post, i did some surfing and found the one with the spelling above.

after the readings, looks like you could use an oil removing hand pump, too."

That's it. Great tool!

That's it. Great tool! I use it to remove transmission oil and other tasks.

Jeff

"thanks! when my hand pump giv

"thanks! when my hand pump gives up the ghost, I'll get one of them to replace it."

"Hey guys, took the boat out t

"Hey guys, took the boat out today nervously, (My other boat is a 21' Searay), so i'm still intimidated by the size of the 37'. Anyhow, the twins seemed to run smooth at >2000 RPM. Cruised about 30-45 minutes to try to burn some bad fuel. Finally was able to get on plane and engines smoothed out at 2500-3000, but would bog down if I increased throttle (I think this is the secondaries opening?). Is this still bad gas, bad coil, fouled spark plugs, fuel starvation, all of the above? Boat goes for a bottom job tomarrow, so I wont have it for a week or so. Thanks for the help.
Bruce"

"hope the bottom is fairly cle

"hope the bottom is fairly clean...if not, you'll have all kinds of performance issues.

you should have a noticable increase in noise when the secondaries open. this is due to the additional air being pumped into the engine. assuming you still have the q-jets, is the bog sustained or brief (maybe up to five seconds)?"

"When I had the initial sea tr

"When I had the initial sea trial, boat was pulled and the bottom scraped, so it is fairly clean right now. The bogging down is a bog. No power after 3000. I'm barely on plane and loss of power when I increase the throttle. When I throttle back a little, engines smooth out. I guess i'm hoping its just bad gas, because both engines are doing the same thing and both run off of separate tanks. Seems when I give it the throttle, something is thrown overboard and draging. I think I hear the secondaries opening, but the power is not there. Again, boat sat since July I think. ie: during the second sea trial, boat had full power with starboard engine running alitle rough.
Bruce"

"doubt it bad gas; more likely

"doubt it bad gas; more likely the quantity.

when you get the boat back, take off the air cleaners and open the throttles. push open the airvalve and make sure the secondary throttle plates open all the way. Also, check the movement of the secondary rod hanger. (see how much the rods move up when the air valve is opened.) it is not uncommon for the cam to be worn out. Most people ignore it when the rebuild the carbs. It is fairly soft plastic and they wear out or crack. insufficient cam movement = no (or too little)fuel thru the secondary circuit.

also, make sure the air valve has the tension spring intact. there's a little spring over the shaft that 'slows' the opening of the airvalve. sometimes the rust up or break - either case warrants fixing.

If that is okay, I'd suggest getting some competent help and take her out. inspect the secondaries when running and see if the fuel is flowing out of the nozzles.

i'm thinking too little fuel vs too much."

"Those tiny, engine-killing fu

"Those tiny, engine-killing fuel filters in the carb body might be plugged. When you replace them, add an in-line METAL can filter before the carb and all will be well in that department.

I assume you're running ethanol gas? If so, it's stirred up all kinds of crud that was happy to lie on the bottom of your tanks.

Jeff"

Starving for fuel typicaly sho

Starving for fuel typicaly shows when you hit the throttle and engine races then slows back.

Your problem almost sounds like distributors are not advancing. When you pull the cap can you turn the rotor about 10degrees and it springs back? Do both of them move and react the same?

Timing needs to be at 10-12 degrees before.

"that's another possibilit

"that's another possibility, especially if the engine temp rises.

I'd characterize the desired state more as 30-32 degrees of total spark advance at 3000 rpm though. If you have an advance timing light, check the timing advance with it. if you don't, measure 2 and 1/4" from the zero mark, on the balancer, and mark another line there. make sure you go in the "Before" TDC direction. that line will show up at zero when you have the 32 degrees of advance. (this works for the fairly standard 8" diameter damper.)"