Sunday, January 31, 2010

Power loss investigation


For that past couple of years, I have been chasing a problem with my motor. My motor would run on three cylinders (at least it seemed like it) if I took the motor past 4000 rpms, especially in 3rd gear. I have changed everything from plugs, wires, rotor, cap and coil. Nothing would make it go away. I even changed distributors. I also cleaned and rechecked the carbs. Nothing would fix this problem. Finally, I was reading were you need to sand down the base of the rotor when using a pertronix ignition unit. I had never done this. I had pertronix units on both distributors that I used to try and fix this. I sanded down the rotor on the current distributor and now the problem seems to have gone away. I can not make happen now. I could put another rotor in and make come and go probably but it seems that may not be necessary as it is not happening now. So I learned something new and will not make this mistake again.

It did not take long for the problem to come back.  So I tried more adjustments and investigation.
I adjusted my carb floats from 5mm/12mm to 6mm/13mm. I also did find a piece of o-ring in the main jet stack for the 1/2 side. This seems to have killed my 2 year old gremlin. I will be continuing to drive the bus to make sure that the gremlin is dead. I may be able to concentrate on something else for a change on the bus.


The gremlin is still alive. I seemed to have affected it with the carb float adjustments. I will be taking the floats out on Friday and weighing them to see if they are starting to soak with gas and getting heavier. There is a weight spec on the side of the float. If I find that they are heavy, I will lower the float from 6mm to 7mm to try and compensate for the heavier float until I get new ones. Hopefully this is on the right track.


 It seems that I am not getting any where with this fix.  I sent an email to and asked the question of how to get at my gremlin that affects my bus. They responded to my pretty detailed question with that they think my gas tank has an obstruction or something. So I will be draining my tank next to see what comes out of it. This is about the only thing that I have not done so far.


I made sure that the tank outlet was flowing with no obstructions and still the gremlin exists. So I may switch my carbs back to my kadrons that I once had on the motor. They will need to be cleaned. Also one of the manifolds has a broken mounting tab. I will have to buy new manifolds and open them up to match the head intake runners. I will also have to modify the vacuum system for the power assist brake vacuum line that gets its vacuum from the intake manifolds. I had modified this from the kadron set up to the dell set up. So all of this will take me a couple of weeks to accomplish. I will be starting this weekend by removing the motor and ordering new manifolds. That's all for now.


I have now swapped from the dells to the kads.  It took a lot of work but it is done now.  I am still having some tuning and linkage issues.  However, it seems that changing out the carbs did the trick for eliminating my gremlin that was a loss of power when I hit high rpms.  Here is what I did to get the carbs installed.

I had to remove the old carbs, fanshroud, thermostat, cc breather and a few other things.

I then had to install a different fan shroud because the manifolds that I bought were shorter and did not clear my original shroud.  This shroud I had already but it is for fuel injection and did not have the hole in the correct location for the accelerator cable.  So I had to drill one.  I also had to clearance this shroud with a hammer for the carbs.

Here is the shroud installed.

Here is the coil installed in a different position than my original.

Here my cc breather is now installed and also you can see where I installed a new holley pressure regulator.

Here are the kads before installing.  New manifolds with the balance tube fittings.

Now the carbs are installed.

This linkage (Scat) is a good one.  However, it takes a bit to get it right.  It also has clearance issues with my breather hose you can see.

Much better linkage ends compared to the original kad linkage.  Much more adjustable.

Here is showing new copper nuts (12mm) I am using on the manifolds for more socket room.  These are self locking nuts.