Trollhole Carb - Lean it out? (1 Viewer)

[eaj71]

Hello

1980 FJ40 2f -- question...

Sorry for the dumb question..

I am running with a trollhole carb, when looking to "lean-out" the fuel mixture.. so it does not run so rich.... is that screw found on the valve cover side ---turned inward (tightening it clockwise)

OR..

is it turned outward - making it looser - counterclockwise?

Thanks
Eaj71

 

[snaggletto]

Not familiar with that carb specifically. However, a fuel screw only adjusts the idle circuit. Tightening is leaner. Typically, you will have to go with smaller main jets to lean out the mid to full throttle mixture.

 

[eaj71]

Thanks snaggleto.

my assumption is that they are meant to function similarly with the AISIN carb.

I have a email into trollhole, but no response so far...

 

[Pin_Head]

How do you know it is rich? Rich produces carbon monoxide, which you can't smell, so you need a tail pipe sniffer test to tell if it is rich. If you smell gasoline, it is misfiring or has a leaky spark plug.

 

[snaggletto]

I agree with Pin Head. You really need to know what your problem is before you 'fix' your carb.

What problems are you having and what RPM range(s) are you having them?

 

[roadstr6]

The mixture screw only has an effect at idle. The jets take over basically at the crack of the throttle. Is it making black smoke at idle? Mine did that and it was because the secondary was open and the carb was bypassing the idle circuit and pulling secondary fuel.

 

[eaj71]

Ah Ha.. yes... black smoke. Would that indicate too much fuel consumption?



A few followups...to help more thoughts...

1. As far as RPM.. I seem to be able to dial it in at 650 rpms at idle, and starts and runs fantastically.
2. I don't seem to smell gas, but it just seems to be too much exhaust smell.. if that makes sense .. compared to my AISIN carb. Just seems
excessive.
3. Also, I get some dieseling at shutdown after a longer drive and an occasional backfire out the tailpipe..
4. The timing is set on the BB (not TDC). Runs great. Tried more advance seems to cause more dieseling...
5. New spark plugs and wires and even a new head from SOR. And new MAF headers...(NOV 2015 purchase - just installed)
6. gas in the sight glass is halfway..
7. Choke idle works fine as does the idle screw - both seem responsive.
8. Cant seem to find any vacuum leaks, but I have ordered a new PCV valve and grommet as tried to sealup any other areas. The MANIFOLD
gasket seems fine.



Now that I think of it I may need to retourqe these as well as the valve cover...but seem pretty solid as is.
Thanks for the insight on the MIXTURE screw...

Any other thoughts?

thanks again
eaj71

 

[roadstr6]

As for the black smoke, yes that has been my experience...too much fuel at idle. Mine actually made a sooty black spot on the driveway before I figured out the problem.

Is your idle fuel solenoid (little electrical doodad on the carb) hooked up? If so, does the truck stumble and die when you unplug it? It should. If the truck continues to run with the idle solenoid disconnected then it is getting idle fuel outside of the idle circuit. The secondary butterfly could be cracked open and allowing fuel to enter. It is also possible to override (bypass) the idle solenoid by setting your mixture and idle speed too high. You don't want to do that. The idle solenoid , when working as it should, provides a nice clean idle with just the right amount of fuel.

 

[edwjmcgrath]

The soot and backfiring from the tailpipe mean unburnt gas. That can either be too much fuel going into the cylinders or one cylinder misfiring or not firing. What RPM are you idling at? Does it idle smoothly? When you turn in the idle mixture screw does the rpm decrease? Have you tried putting your timing gun on each of the spark plug wires to see that they are all firing consistently?

When I first read your description, I suspected junk (machining debris) in the needle valve so that the bowl was overfilling and flooding the carb. This would not be unheard of in these aftermarket carbs.

 

[eaj71]

Thanks for the additional rocks to look under...

The Idles Solenoid is hooked up an is getting 12v... I can hear it click... when it get plugged in...but I have not tried to see if it runs without it. So we will try that.

I will also check each cylinder - I havent done that yet and a new pressue test.

It seems to idle a +/- 650 rpms and does idle smoothly, by the idle mix screw - the one facing the firewall - not the fast idle does make the idle go up and down. The screw facing the valve cover does not seem to do too much....

eaj71

 

[eaj71]

Update:

1. I rechecked the timing and still
At 7 btdc

2. Runs without the idle solenoid plugged in. This is not supposed to happen I believe

3. Redid the lean drop All idles seem fine

4. Tons of black smoke

5. Lots of fuel consumption

Soo.... I'm thinking it's in the carb. What might you think?

Thanks
Eaj71

 

[Curt]

If it runs without that idle solenoid then i think thats the problem. Connect that and see if you get better results.

 

[eaj71]

Yup. I think so...The thing is ... Is that it runs with and without the idle solenoid being connected

It is not supposed to run with it not being connected


So the next question is where do I go from this? I will try trollhole
But before I do I want to make sure this is the issue


Any other input?

 

[tlc762]

It should not idle with the solenoid disconnected... It is getting fuel from somewhere else other than the idle circuit which is controlled by the solenoid. The solenoid also helps to prevent dieseling after shut off but cutting off fuel to the engine without the 12V engine/ignition on power.

 

[emac]

Well, funny this thread is going on today. I have been sorting some issues with my 40 rebuild (mostly brakes and tranny). The engine was rebuilt and I put on a thole carb and dizzy. It has been running great. Until lunch time today. It started running rough, missing, black smoke, no idle,etc. Emailed Marshall and he thought I should check the float. I nursed it home and checked things out. Heres what I did:

Removed the carb, opened the top, and made sure the float was working. Moved some things up and down, nothing major. Wiped out some grime, checked the linkages and secondary to make sure they were closing properly and put it back together. I noticed my vacuum line to the PCV was a bit loose, so I replaced it thinking that may have been causing a manifold leak.

I installed the carb and plugged in the wire to the solenoid. Hmmmm, that didnt feel like it went together firmly. It clips together but the metal connectors dont seem tight. I tightened the connector and fired it up and it ran perfect.

Was the float hung and I just got lucky and knocked some trash out? I doubt it. DId I have a vacuum leak? Possible. But I really think the problem was that connector. I think it was bouncing around and hitting every now and then.

My rig has only a hundred miles or so on it since I did a complete restoration. Fuel system is all new. Tank, lines ,pump, filter etc. I have only put non ethanol fuel in the system.

This may not help, but I thought I would share it.

 

[eaj71]

ah ha.

Yes that would make sense tlc762 ! Helps correlate issues

Any other comments

 

[eaj71]

Emac

Thanks for your story. I too have emailed Marshall and I am
Waiting a response

The solenoid is working as when I plus it it the engine does change rpm.

But again it should die when disconnected.

I might just take the top off the carb and see what happens

Thanks
Eaj71

 

[emac]

Make sure your linkage isnt keeping the secondaries open dumping extra fuel into the carb. If it doesnt die when the solenoid is disconnected thn it is getting fuel from somewhere else, I would suppose.

Be careful removing the top. My screws were very tight, and the gasket is fragile. Easy to strip a screw. When I had it apart I blew into the fuel line and moved the float up and down. It seemed to be working. Plus, when it was running the fuel level was about 1/2 way in the sight glass. Here is what Marshall said in his email to me:

"Check the float level. If it's off the float may have gotten stuck or something got in the needle seat. If it's stuck you can take one of the bowl drains out and use a paperclip and gently move the float and see if that works. If not you will need to pull the top half off gently using a thin blade to pry the gasket from the main carb body. Remove float then remove the other gasket. Then use a pair of lock pliers to break free the brass float needle seat. Then use a large screwdriver to unscrew. Then clean and resemble. Sometimes ethanol gas eats the screen above the needle seat. "

 

[eaj71]

Sounds great. Thanks for the direction!!!

 

[edwjmcgrath]

If the idle solenoid isn't working, you'll have to crank down on the idle speed screw a lot to get it to idle. This will open the throttle plate enough so that you are bypassing the idle circuit. This means that the idle mixture screw isn't going to do anything either. Sound familiar?