1975 IL Six bogs out after about 2500 rpm

[minstral]

I have cleaned the carbs, put in new plugs and set up the timing to the specs that it calls for. Have run it on a "new" remote tank with fresh fuel..have replaced a failed Switch box....seems that it is not getting enough fuel....starts okay and idles very smooth.....ease it up in rpm and everything good until about 2500 rpm then bogs down.....I am stumped.....any help would be appreciated.......thanks

 

[minstral]

Re: 1975 IL Six bogs out after about 2500 rpm

Oh and I forgot to mention that the fuel pump has a new kit in it....but am confused about the second line that seems to come from the #6 cylinder on the compression side to the fuel pump....understand the one coming from the primary compression side of the piston to the fuel pump.......??????

 

[Clams Canino]

Re: 1975 IL Six bogs out after about 2500 rpm

They are push / pull. <br /><br />If this is a new/unknown install it may just be overpropped. There is a hump at about 2500, if it can make about 3000 the power-band really kicks in.<br /><br />-W

 

[minstral]

Re: 1975 IL Six bogs out after about 2500 rpm

CC<br />Thanks for responding, I worked on this motor a few weeks ago cause it had alot of debis in the carbs, and the WS filter was full of water Put in a new set of plugs. Then it came back cause the Switch Box had failed. Replaced that and when customer was running accross the lake it just suddenly slowed to around 2500. Changed to a portable tank to see if it was a fuel restriction from the main tank but that made no difference. Starts, idles and runs slowly really well but as soon as you give it throttle it starts to go up then bogs down. Pumping the primer bulb does not change it at all...this one really has me stumped

 

[Clams Canino]

Re: 1975 IL Six bogs out after about 2500 rpm

Gotta go back to the beginning: compression test, link n synch check (are all 3 carbs opening?), fuel pump / clean carbs for real, check etc. <br /><br />Are all 6 plugs firing? Inside of cap clean? Hows the carbon brush?<br /><br />There's only about 10 things that CAN go wrong with these anciant beasts.... you just have to find the one. <br /><br />-W