Rebuilt Carb - First start attempt is a no-go (1 Viewer)

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Oy. IM is on the back side closer to valve cover. Idle speed is closer to the right side tucked in at the base of the carb. The screw seats down on a metal linkage. You can see the linkage move as you tighten the screw in.

Both the front and back adjusters were put all the way in, then backed out 2-3 turns, both pressing the metal against it.

Apologies for the novice questions. I have been working on FI engines for nearly 20 years, but this is my first endeavor into the carb world.

Appreciate your help big time. I will double check them all in the morning.
 
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NeverGiveUpYota

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Both the front and back adjusters were put all the way in, then backed out 2-3 turns, both pressing the metal against it.

Apologies for the novice questions. I have been working on FI engines for nearly 20 years, but this is my first endeavor into the carb world.

Appreciate your help big time. I will double check them all in the morning.
It’s all good. I was there not that long ago. My apologies writing ‘oy.’
 

Gretsch

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1607781643669.png


These pictures may be hard to figure out the carb orientation and thus hard to use. You should be able to locate the 4 vacuum lines going into the carb on the valve cover side to get your bearings and thus figure out where the screws are. The AC Idle up is the easiest one to spot and to get access to. Its on the front of the carb. There is a big vacuum pot with a relay arm coming off where the screw sits. I don't think thats important here for you now, but just for future reference.

Some adjustments can be found here in this post:


Do you have a copy of the FSM? Everyone on here starts somewhere, but the best place to start is to read through the FSM to familiarize yourself with the information and procedures contained within. Its kinda hard and tedious to direct someone post by post for something as delicate as carb tuning.

Take a look at the Mud resources tab on this forum. Lots of manuals there:

Resources | IH8MUD Forum

Who rebuilt the carb for you? Was it one of the carb gurus on mud or someone else?

Also, you mentioned trying to hardwire the ICS to the battery and heard a click. When you hard wired it, did you try and start/run the engine with it hardwired and you still couldn't get it to start and idle properly, or did you just listen for the click without trying to start the engine? HTH.
 

John McVicker

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Buy a can of ‘Starter Fluid’

1) don’t try starting for 15 minutes
2) have someone spray starter fluid into the carb
3) while you turn the key and try to start
4) have your helper spray burst when it sounds like it’s about to die
5) report back

If you are able to keep it going with short burst...then you know it’s a fuel issue. This is not dangerous but still have a fire extinguisher at hand...you are working with gasoline etc.
 
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thanks for the info Gretsch. I’ll be getting back to it shortly.
I do have an FSM, and have done a bit of reading, but admittedly a lot of the carb stuff swings right over my head. I will continue to read more.
Mark of Marks off-road in Burbank rebuilt it.
When I hard wired the ICS, I heard the click, just the same as when plugging it in, but the starting experience was also just the same (uneventful).
Worth mentioning that calling my start up a start up feels like a stretch. It only (barely) fires with the choke out, and doesn’t reach more than maybe 200 rpms then dies. It’s also very rough (but maybe because of the low rpm). Throttling once it “starts” might make it fire a bit longer, but it definitely does not rev the engine.
Going to read your post, other posts and the FSM.
I’m moving this week and really hoping I can drive this thing and not have to have it towed.
 

Gretsch

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but admittedly a lot of the carb stuff swings right over my head

You are not alone there. Carbs are black magic science in many ways. I think you are in good hands having Mark rebuild it though so thats good news. It sounds like the ICS idea is sufficiently ruled out as well so thats progress.
 
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Ok- Continuing to mess with the adjuster screws on the carb.

I can now get it to "start" (ish) without the choke, but with throttle instead. And I am not reaching around 500 rpms, but with throttle held down.

I am getting these loud screech pops. See video below.

Note: air cleaner is not on right now.

(669) No start -diagnosing - YouTube
 
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NeverGiveUpYota

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Backfire into carb is what the pop sounds like. Carb adjustment. Try to video the top of the carb to see when it pops if it’s flashing. I had the same issue way back when.
 
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Wheezing and pushing air when it should be sucking. Make sure your dizzy is close to being in the right spot and the valves are adjusted.

Put the engine on TDC by holding your thumb on the #1 spark plug hole and feeling for the air push. Do this w/the coil wire removed...no need to start the engine, your just turning it. Then remove the timing window door and look at the timing mark on the flywheel and make sure the indicator is pointing at the TDC line on the flywheel. You may have to turn the motor by hand a little to get it there. Next pull the dizzy cover off and make sure the pointer in the dizzy is pointing between the 3rd and 4th plug hole and the #1 piston is up. " you can feel it the #1 piston by putting a screwdriver tip down in the plug hole and turning by hand until its at the highest position. If the rotor is pointing away from the block you may have it stabbed 180 degrees off.


1607742755457.png


In this position you adjust the valves a and b, then turn the motor around again and when the pointer is on tdc again and #6 piston is up, and the rotor is pointing away from the motor. then you adjust the valves c and d.

valve adjust table.JPG
 

Gretsch

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Backfire into carb is what the pop sounds like. Carb adjustment. Try to video the top of the carb to see when it pops if it’s flashing. I had the same issue way back when.

Would have to agree it sounds like intake popback. I don't know if I can see a flash but it sounds the same. You should prolly again check the timing as suggested above by @g-man, the firing order (which plug wire goes where), and even run the test @John McVicker suggests in post 44 to see if this is still due to fuel delivery. Popback I think can be caused by severely lean condition (carb adjust) or improper timing. Air/mix ignited when intake valve is still open allowing flame front to reverse back into the intake and out through the carb. Something like that. Engine gurus can correct me here. In any event OP I think you have all the tools needed now to correct this. Some good ideas from folks of things to try.

@NeverGiveUpYota are you saying you were able to solve this in your situation by adjusting the carb?
 

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