cvlngineer
Petty Officer 2nd Class
- Joined
- Jan 22, 2002
- Messages
- 137
Could someone please post the proper carb jet sizes for a 1975 70 hp Johnson?<br /><br />Thank You,<br />cvlngineer
I was out messing with it a few minutes ago. I set the pickup timing and resynched the carbs. I did notice some improvement. I am not certain about the lean condition any longer. I took off the choke linkage, and closed each choke valve, one at a time. It killed the engine each time, however, with the linkage on, closing the choke plates in unison part of the way increases rpm's, closing them further kills it. <br /><br />I re-rebuilt all three carbs last night, soaking them in carb cleaner, etc. I replaced the float valves and seats, and discovered an oops that I made. I took the #2 carb off 3 or 4 days ago, and took it apart to look at it. It was getting dark, so I put it back together a bit too hastily. I put the float in upside-down. I fixed it and did notice an improvement, duh! At least now it acts like it wants to idle in gear. <br /><br />My manual says to set the idle at 700-750 rpm in forward gear, under a load. Do you have any idea how that would relate to idle rpm in nuetral in my barrel? With the timing set right at pickup timing at TDC, throttle plates not open, it idles at 1150 rpm or so. Putting it in gear in the test barrel, briefly, before it blows all of the water out, the idle drops down to about 700-750 rpm. A neutral idle speed of 1150 just seems a bit high to me, any ideas?<br /><br />cvlngineer <br /><br />cvlngineer <br /><br />I think that the jets in the carbs are, indeed, marked 54 D and not 64 D. I believe I wrote it down wrong.<br /><br />You say that those carbs were used on 1978 70 hp motors, will they work on a 1975 model?<br /><br />Also, could you elaborate on retarding the timing to move just before the fuel is introduced? I want to make certain that I do it right. Do I set the pickup timing 2 degrees before TDC or after?<br /><br />Thank You,<br />cvlngineer