Talked to the repair shop where the car is now. They let it sit over the weekend to make sure it wasn't leaking anywhere. All good. Checked their work and made a couple adjustments after getting it back from the rebuilder. All good. One of the mechanics took it for a test drive of about 10 miles. Fuel pump died. Sometimes I think my car is the opposite of Christine. I fix mine up and she destroys herself. It's almost comical. Almost.
So I have the car back and after some timing and carb adjustments, she drives pretty well. I'm experiencing some vibration at around 2000 rpm when in park though and also to a lesser degree, at idle. I've got about 18.4" of vacuum, timing set to 12°, new plugs, newish wires/cap/rotor. The shop told me after the 1st test drive that the carb (Autolite 2100, 2bbl) had some trash in it that may be clogging it some (jets and/or needle and seat). They seemed to think my carb is crap, but I'm not so sure. If the main jets are getting some trash in them, wouldn't I be having more problems than this? Think a simple carb rebuild could be the solution?
It's almost impossible to have a 2100 that can't be rebuilt, just about the simplest carb there is... If the main jets were plugged, it wouldn't do more than idle...
Last night I took off the cap of my carb and there was some trash in the bowl. I didn't have much time before dark but I cleaned what I could. I squirted carb cleaner thru the jets and cleaned the needle and seat to try to help some. Like I said before, the timing is correct and I have good vacuum readings. It still just vibrates around 2000 rpm....sometimes it sputters and wants to die when trying to accelerate and sometimes feels weak going up hills on the highway, but my gas mileage isn't bad. Thoughts? Just seems like it's probably trash for most of these issues, but the vibration part has me concerned. Edit: This vibration (to some degree) has been there every since my first motor rebuild (now on second). The hesitation/sputtering is a recent development. It seems like my carb has some serious issues that nobody has been able to figure out, me included. I did see a Holley 2300 350cfm new in box for $75 at a local fleamarket, but I think it was a marine carb. I couldn't use that, right? No A/T kickdown? I think the differences between the marine and street has to do with coast guard regulations to help prevent backfiring (for safety reasons).
Ok, over lunch I cleaned the bowl some more, sprayed out all the passages, etc....this took care of the hesitation/sputtering. The vibration is still there though. One thing I noticed was that when I disconnected my vacuum gauge and the the motor starts chugging due to the vacuum leak...that is kind of the sound and feel of the motor around 1500-2000 rpm. It's not nearly that strong, but it has that same kind of hollow/chugging sound and rough vibration. Another thing I noticed is that my exhaust note isn't a sharp as before. Given that I've got a strong and steady vacuum reading, do you think this could still be carb related? Any other ideas?
It's one of those clear glass and white element filters so I can see what's coming up from the tank and keep an eye on how. I'm not positive that the guys that were supposed to have done the carb rebuild back on the 1st motor rebuild ever really broke it down and cleaned it right. When I can, I plan to take the carb off and completely tear it down and clean it really well. Until then, I'm just trying to figure why this vibration issue continues to haunt me. I figure it's got to be one of these: 1) Carb issues 2) Bad distributor cap/rotor 3) Bad plug wires 4) Weak ignition coil 5) Harmonic balancer shifted Edit: I have noticed my Tach dropping below the real RPM occasionally too. It drops the most at highway speeds...usually from about 3000RPM down to about 2200-2500RPM. Could my distributor itself be the problem, maybe from a worn bearing/shaft? I also think the harmonic balancer is the same as the one that was on my 302 that destroyed itself. I'm wondering if it could have shifted some but otherwise seemed ok and was reused. That is another part that has carried over from the last motor when I had the same problem.
If the vibration is approx the same at 2K RPMs on the highway vs parked it's likely some type of imbalance problem... The dist, wires, carb etc isn't likely the problem, usually causes a miss/stutter but not vibration... Sooo I'd still suspect a mismatch of components or maybe the harmonic balancer is defective... Does this engine have the mounting boss on the left side of the block to mount clutch or the auto trans shift linkage? If so it should be a 28oz imbalance engine and the original front balancer would be correct...
Thanks Krazy, the more I think about it, I'm a little skeptical of my harmonic balancer. Guess I need to start looking into this problem more. Any easy way to trouble shoot the balancer to see if it EVER slipped but maybe isn't slipping now?
If the timing marks are still correct in relation to TDC, it hasn't slipped... I'd think if they were off(slipped)enough to cause a vibration, it'd be impossible to set the timing using the marks... You could insert a piston stop through #1 spark plug hole and check for sure, but if you can see the piston and marks are lined up it's probably OK...
Ok, after a little troubleshooting, it doesn't look like it's the harmonic balancer based on the timing marks. I double-checked voltage to my Pertronix to make sure it was 12V and also cleaned up my dist. base plate which was giving me a higher ohm reading (4) which I wanted to be 1 (max). I pulled plugs from the distributor and each gave very close to the same RPM drop, so the ignition seems, although my coil is the cheapy BWD O'Reilly special and not sure how hot of a spark it sends. My carb is still acting a little funny though. I can give it some throttle and it wants to stick at a slightly higher RPM than before. I can hit it with the handle of a screwdriver and it settles back down. Maybe some trash made it past the jet openings and partly clogged one of the passages. At idle it wouldn't be really noticeable but at speed wouldn't that give me a lean condition to 4 of my cylinders?
