stumped
 

O.k. got my timing issue fixed, boat runs awsome. Idles @ 800 neutral, 700 in gear. Runs strong across the board. Dialed in I saw almost a 8mph gain but after a long run when coming in to dock if I pullit into neutral it idles up to 1800-2000 rpm. :confused: really fun too dock I wont put it back ing gear revving that high so its like running a crash box. Only thing I can think of is that timing is getting stuck at parcial advance cause that will bring up the idle. Anyone seen this problem ever. Motor is a BBC.

Re: stumped
 

Advanced timing would not cause the engine to stick at high RPM but if stuck at that RPM it would be advanced because of the higher RPM. Is the throttle linkage not returning? Perhaps the secondaries staying open just a bit after being opened all the way?

Re: stumped
 

I follow what your saying but advanced timing at and idle will bring up the idle (at least a little) cause when setting the timing on the motor if I turn it up from 8 to say 10-12 deg. the idle raises. :confused:

Re: stumped
 

Vacuum leak (don't think that would bump it up 1000rpm?) or something hanging up and not letting carb return to idle position?

Re: stumped
 

you guy's are right I stand corrected (type without thinking) timing alone prolly wont do it. With very little vacuum lines the only thing I can think of is carb base gasket. Whitch would make sense that it would only leak when its real hot, since everything expands. Thanks guys I'll check that tonight.

Re: stumped
 

i had a similar problem last summer, it was my throttle return spring.... held the throttle just enough to run 3-400 rpms higher.. just a thought

Re: stumped
 

check throttle return springs, cable, and make sure plates arent sticking. Also maybe choke is stuck on?

Re: stumped
 

I have a similar problem in both engines, just not as bad. After a hard run they like to go to 1100 -1200rpm at idle. This seems to last a couple minutes then then start dropping back down to normal, which is about 800rpm. I have fooled with both carbs several times and know the butterflies are closing properly. I am leaning towards heated air going into the carb from a hot engine room. Doesn't really make sense to me because I think that would create a rich a/f mix (air less dense) and therefore lower idle. Usually lean causes a high idle. Just thinking out loud here and looking for ideas myself.

BT

Re: stumped
 

I am having the same problem on A 1990 454 and I believe it to be the secondarys stuck open!

Re: stumped
 

Racingbird may have a thought with the choke- if choke is hooked up is it working properly and if not hooked up how is it disconnected? might be the idle step up flopping around (yes flopping around is a technical term) if that moved and the choke plate didn't close that would bump up the idle a lot?