I'm either about to lose my mind or my hair over this one. I need some gurus to help me sort this thing out. About a year ago I swapped in a '73 vintage 360 from a Class C Motorhome into my IH Scout 2. It was a great running 90k mile motor and trans, and the install was a snap really. Even with the problems I'm about to lay out, it still idles as sweet as a 90k mile motor should. I meticulously went through the wiring to make the Chrysler alternator, voltage regulator and electronic ignition, work with the GM style wiring the Scout has, including an ammeter bypass.. After I started to drive it, I noticed a little bit of a surge and sputter during cruise. I bet on a bad carb, and bought a kit. It didn't seem to help.

So I looked into the ignition. One piece at a time I go after it. Reman distributor, new module and coil, and even a new ignition switch. Nada. So now I replace the spark plugs, check the cap, rotor and wires, and find,..... still nothing. Then I start to think vacuum leak. I sprayed starting fluid everywhere, nothing. I replaced a couple of small vacuum lines that might be an issue,.. nada. No change without the brake booster attached even!

Then a friend suggested grounds. I add a bunch of grounds and clean up the ones I have. Still nothing. So it has been mostly parked. I had to drive it the past couple of days, so I filled it up with fresh gas and took off. It's even worse. So much so that it misfires randomly out the exhaust, especially on deceleration!

What am I missing? Please help, I haven't much sanity left. Thanks!!

Check compression?

Sounds lean to me, ethanol gas makes all these old motors run lean if it's a carburetor and will cause surging and misfires under load.

Small piece of dirt in a metering jet could cause all those problems. It has happened to me.

R.

If it still has the Holley 2bbl factory carb you can bet it is warped from the air cleaner stud pulling on the body. If that is the case take carb apart and check upper flanges with a good straight edge Next is the mopar elec ignition if you are using it. They are very sensitive to ground if you have a 4 prong ballast resistor make sure you have the right box, frankly I would go pertonix and scrap it. 60s that year are very prone to bad valve seals and to plugged manifold heat passages, intakes love to blow out and check 5-7 for blown head gasket it won't over heat but will give you misery. Check back of head on driver side

I see I left out a few details. This truck is running the stock Carter 2 BBL right now. When I tested the engine before buying, it fired right up, cold. It only seemed to have an issue with the accelerator circuit, so I assumed the problem was a bad accelerator pump, since motorhomes typically sit a lot. Idles steady and smooth as could be. The motor was pulled in the summer time, and went straight to my engine stand in the garage. And I went about installing it that next spring, so I don't imagine any issues will arise from that. About the only time that it runs right aside from idle is when I'm deep into it. It seems to quit these problems, but I've only done that test a time or two. While installing the engine I found the timing chain was bad, so it was replaced with a new double roller at that time. I'd be surprised if it was a rotor phasing problem, because the rebuilt distributor is a Cardone unit, the kind you usually get at most part stores. But its something to keep in mind I guess. I haven't done a compression check because of how nice it runs at idle, and because it doesn't burn or leak any oil. But it's worth a shot I suppose.

Now I'm wondering if there's a way for the intake to have a crack or something in it, where it could act this way. I've never had a cracked intake, but it did come from a B300 motorhome chassis. And those earlier vans were known to crack and warp exhaust manifolds due to high underhood temperatures. I suppose a cracked intake isn't out of the realm of possibility. I'm considering an Edelbrock Performer intake and dropping the ThermoQuad that I have onto it. But the TQ is an untested unit I got from a pick-up in the bone yard about a year ago. I really would rather pinpoint the drivability issue I have now, before I go about adding more. But at this point, maybe it wouldn't hurt?

Just me, to k.i.s.s. I'd try another carb on there