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Discussion Starter #1
Long story short, I hate this Jeep. Trying to help a buddy out, his father replaced the engine with a crate motor, new HEi dizzy and a 34 dgec weber/solex carb. They never could get it to run. Has maybe 15 minutes on the engine, has sat for 5 years.

I have it at my house, fixed the dizzy timing, spark plug routing, vacuum leaks and replaced fouled plugs, replaced gas/filter, and oil.

Runs fine from maybe 3k up, to start it I literally have to floor it wide open, then it runs and will rev up and down smoothly.

Try and bring it down to idle and it dies immediately, typically it blows a big ass cloud of raw fuel out of the carb. I have the fuel pressure regulated and have replaced the carbs idle jets to what weber recommended for this altitude and still no dice.

I am not the most carb savvy guy in the world, but this can't be that difficult. Anyone ever see any type of engine do this and have any advice of what direction to head, I am at the end of my rope.

Here is a video, it's cold, phone was hard to hold onto so pardon the random shaky parts:

20111201_153939.mp4 - YouTube

Thanks for any advice
 

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Has to be a timing issue, beings as it was a new motor, there is the possibility the timing set is installed wrong. Are you positive it's not 180 degrees on on the distributor? It is real easy to do on these motors and they will run at higher RPM's. Not much else can cause these problems.
 

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Discussion Starter #3
It was about a month ago i timed it. I checked the balancer and the position of the rotor, noted it looked off a tooth and re-dropped the dizzy. Then later I did the vacuum line in the cylinder trick to watch the pistons movements to try and determine if the balancer was slipped. I think I could see the valves on #1 closed through the valve cover oil fill hole but I can not remember, maybe I need to pop the valve cover and make sure I am at tdc by verifying the valves are both shut. I also considered the timing set was on wrong.

And it is like flipping a switch when it dies, it just dies, I have never got it to idle.

I have also never heard of an engine that will run 180 out at higher rpms, that is very cool.
 

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Air/fuel mixture would be my first guess if you're dead sure on the timing. Check the webber instructions. Typically they'll say something like "start with both screws at center; adjust fuel in 1/8th turn increments"

Have you checked for voltage drop at the alternator? Not sure of your HEI setup, but if you're not giving enough juice to keep the spark going... could be an issue and it makes sense that it only runs over 3k. Running a ballast resistor with the HEI?

Grasping at straws here- but just some ideas...
 

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Discussion Starter #5
This carb has a single mixture screw, I have run it all the way in as an experiment, no change. Have used the weber site and some found links online for trying to set the carb, It has the base settings listed and I have tried them.

I have 12v at the dizzy when cranking, I have not checked when running, I will do that.
 

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Discussion Starter #7 (Edited)
The more I think about it...

That is way too much blowing back into the carb, it has to be compression gasses.

Revved up, there may be enough overlap in the valves to promote running at a higher rpm, as in the the messed up timing does not come into play, but I am confused as to why it would run SO smoothly at upper rpms.

I am going to pull the valve cover and roll the engine while I watch the rockers and verify tdc.

Then I will double check where the balancer is pointing.

I guess from there if all looks well I pull the timing cover.

One thing I have never understood fully is how long the valves stay closed turing the compression stroke. What I mean is, the balancer could be pointed at tdc, but the cam could be on the round, not raised portion of the lobe for several degrees. Which I have always thought meant that a slipped dampener or incorrect chain could be missed without a visual inspection of the chain.

If that makes any fucking sense :laughing:


Edit: I am sure everyone knows but what I am doing with the screwdriver in the video is changing the idle screw, I try and idle it down at first, then it dies and does the fuel blow, then I idle it back up and try to fire it but it is so loaded I would have to rev it sky high to get it running again. But it is hard to do while holding a phone, trying to start it, and watching out for the fan that has no damn shroud.
 
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