76 115rude

[wavrider]

Does not want to idle at low speed, move throttle up it will run around 1500 to 1800 RPM.

I put the fingers in the throat of the top carb and she will run semi ok at idle.
Put the fingers in the bottom carb and acts like she is choking out. Everything points to the top carb being lean that I know of? I still have alot to learn though.

I cleaned rebuilt both carbs this morning, they are clean and all passage ways and venturi's, orfices clean. Deep Creep, carb cleaner,acetone and wd40 were used, wire through the bottom of the bowl jets, compressed air, everything is as it should be.

Compression is 120 on #'s 1, 2, and 3, #4 is 110, it had a bad head gasket so repleced it on 2 n 4.

Good spark checked with spark tester all 4 nice n blue.

On the v-4 there is a top carb and a bottom carb, do they have different jets? With the top carb being a little bigger for the fuel or maybe idle air jet smaller?

I think it may be I have two top carbs on this engine, of course part number tags are off so really cant tell what carbs they are. Thanks for the replies.

 

[HighTrim]

Re: 76 115rude

There are seperate part numbers for upper and lower carb.

"http://www.crowleymarine.com/brp_parts/diagrams/29246.cfm"

Also does sound like you have a fuel delivery issue at low RPM's.

Get a vacuum gauge and hook it inline on the fuel hose before the engine, along with a clear section of hose. Take it for a spin, noting the readings and monitor the fuel flow through the clear hose.

Findings:

-Vacuum of less than 2 inches and air bubbles in the clear hose indicates an air leak into the fuel system
-No air bubbles and less than 2 inches indicates a bad fuel pump
-Vacuum over 4 inches indicates a restriction.

Sample gauge

"http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&sspagename=STRK%3AMEBTOX%3AIT&viewitem=&item=4610113711&_trksid=p3984.cTODAY.m238.lVI"

 

[ezeke]

Re: 76 115rude

The carburetor throats and jets are the same on both carburetors. What makes them different is the throttle connection and the manual choke fitting.

Watch the throttle plates while advancing the throttle, they need to be perfectly synchronized.

Watch the fuel coming up through the capillaries behind the throttle plates; they need to all be clean to get a good idle.

 

[wavrider]

Re: 76 115rude

Yes sir I observed the fuel coming up the capilaries, even felt them when i put the fingers in the throat.

Thanks for letting me know about the part numbers, was curious about that.

I just "woke" this engine up from who knows how long a dormant phase it sat.

The lync n sync was incorrect, adjustable linkage was on the chokes with no adjustable linkage on the butterflys.

Just remembered what I think Ezeke told me last week, the ole rudes fuel pump does not like to pull to much in a vertical position, I had the tank on the floor and fully away from the engine stand where I was working on the engine, may be the problem so I will elevate the tank and most likely rebuild the fuel pump after I get the vacuum test done. Thanks.

 

[ezeke]

Re: 76 115rude

To adjust the throttle plates you set the bottom one first, after loosening the screw, then bring the top into alignment with it, and tighten the screw.

 

[wavrider]

Re: 76 115rude

This one has me scratrching my head, been at it since 7 am today, loved every minute of it.

took carbs back off, cleaned again, found no debris, looked at the reeds, they looked fine, all were closed and so no opening in them from looking at them with a flashlight everything in the carbs were clean as before. re-installed carbs, ran the same way.

Hooked the timing light up, found intermittent miss on #3, inspected plug wire looked like white film by the coil, replaced the coil and now everything firing good on the timing light, was able to idle down to around 500 or 600 rpm, miss was still there but not as often or as bad.

Installed low pressure electric fuel pump inline, by passed the regular fuel pump, still had intermittent miss at low idle so eliminated fuel pump, hopefully eliminated ignition, new plugs gapped 030,????

Maybe I just have it idled down to low, book says 600 to 700 in gear i think, cant remember brain dead now, lync n synk is god according to manual,
this motor is almost ready to be mounted to the Skeeter, but want make it correct before installing. thanks for the tips and replies,

 

[tashasdaddy]

Re: 76 115rude

run a small wire thru low speed jets, and the holes inside the core plug.

 

[wavrider]

Re: 76 115rude

thought about this when I was cleaning up, the bottom carb, port side spits out a fine mist when the engine misses, just a little spray, I had my fingers in the throat of the carb and felt the spit/cough/sneeze whatever it is, thanks TD I will try that tomorrow, no Tuesday got to take the daughter to the mall after work.

 

[HighTrim]

Re: 76 115rude

Is the cough more prevalent cold than after it is warm?

Check your idle air jets.

Refer to rodbolts comments in this post.

http://forums.iboats.com/showthread.php?t=235492

 

[patrick4266]

Re: 76 115rude

What size of wire do you use for those bottom jets?

 

[HighTrim]

Re: 76 115rude

A machinists wire would work.

 

[allymoss]

Re: 76 115rude

Just a thought, you said i coughed, could the timing be ever so slightly out?? as to not affect when running at higher RPM's or have I got that the wrong way around?

 

[wavrider]

Re: 76 115rude

Is the cough more prevalent cold than after it is warm?

Cold it runs pretty smooth, after it warms up makes me think it was possiblecoil so I hookd the timing light up and found spark.

Thanks forthe replies and almost got this one figured out, will read rodbolts thread, thanks

 

[wavrider]

Re: 76 115rude

I think RodBolt hit it on the nail head, jetting for idle air, I willook into that when I get a chance, thankas for the replies, Idle air to lean ,,go figure, will try the toothpick trouble shooting

 

[ezeke]

Re: 76 115rude

That might be correct if you had those jets, but you don't.

 

[wavrider]

Re: 76 115rude

Nope I don't have those jets.

Went to the cross-flow, decided I had no idea why it was not idling smooth, so figured I would install the tell tale, took the ground wire loose on the starboard side to punch a center point and there was a lot of corrosion under the connector, got me thinking??

all said and done I removed all the coils and the grounds, wire brushed them until I could see my toothless smile and re-installed the coils, installed the tell tale, filled the barrel and fired it up, no miss, no hesitation and still scratching my head, tell tale works fine.

Installed the front covers on the carbs and the electric choke solenoid, going on mount it this week, hopefully try it out this weekend,

Still dont know if I got the miss fixed but could not get it to miss again today.
thanks for the tips and replies