Carb Tuning / Vacuum Problems?

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If your compression tester is accurate it's no wonder it doesn't run good. That's very low compression. How many miles on this engine? Did this happen all at once? If so it's possible the timing chain jumped a notch.
 
Shouldn't be too many miles on the engine. Guy I bought it from claimed to have just rebuilt it but who knows. I've put about 2000 on it since I got it.

Hard for me to say if this has happened gradually. When I first got it, there was a thermoquad on there. It stumbled under hard throttle and I had problems getting it to start when warm, especially if it was warm but not hot. I also played with timing at some point there without a timing light, which probably wasn't too smart. It kept giving me trouble starting and the TQ looked like it needed a rebuild so I bought a new Holley since it seemed better for a newbie. With the Holley on it starts great but has the current problems I'm dealing with. Sorry I can't be more specific but I didn't know as much when I got the car as I do now so I can't really describe the symptoms.
 
Unfortunately many people claim things that aren't true. Any time I buy a car and the person claims the engine has been rebuilt I question them as to exactly what was done and ask for receipts. Hate to have to be that way but you know how it is these days, it's hard to take a persons word. The compression test is a valid indicator of an engines condition. With yours being so low there is something drastically wrong there. Until it's corrected it'll never run "right".
 
Another thing with the compression test is that the starter cranks pretty slowly compared to a lot of others I've heard, could cause lower readings right? Not trying to say there isn't a big problem here but she pulls pretty well and took me on a 1000 mile road trip last summer with no problem, just trying to go from simpler to more complicated problems.
 
I have a 360 with 280H in my 66 Cuda. In neutral it idles at 900-950 with 12in vac. In drive the vac is 9-9.5 in vac. It will not idle correctly under 900-950 in neutral. Thought this might help you out a little.
 
You originally said you used carb with adaptor,, I'd be interested to know, if one of the adaptor gskts has sucked in, or is in some other way not sealing under the carb,, that would cause all of aformentioned stuff,, and lookin close at those plugs, it looks like some plugs running lean, like maybe one side of carb sucking air,... definately plug that vacuum tee..

and I might have missed it,, but does eddy carb have power valve, like holley, and if so, did you put in low vacuum power valve? you may have to mess with that later...

and those compressions are all even, that's really good,, dis-regard #'s stated,, they change with diff gauges..
 
If the starter is cranking slow that will definitely affect the readings but generally if the starter cranks it good enough to start it under compression it'll crank fast enough to give proper readings with the plugs out and throttle open.
 
inertia said:
and those compressions are all even, that's really good,, dis-regard #'s stated,, they change with diff gauges..
Click to expand...

Even #'s are good but when the compression is down 50 lbs. something is drastically wrong, even #'s or not. Gauges should all read very close to the same. If not the gauge is unreliable and needs thrown away.
 
It was a rental gauge so who knows how accurate. I might rent another one (or just buy one) and check again to see.

There is an adapter under the crab (square bore carb to spread bore manifold), but I just had it off and replaced both seals and they seem to seal fine. Also have sprayed carb cleaner all around the base and no change to the idle so there's probably no vacuum leak. Vacuum tee has been removed and replaced with a plug and sealer tape.

bbeep - thanks, I will keep that in mind. The vacuum seems about in line with yours until I drop it in gear. Honestly I'm not sure how it runs with the vacuum that low in drive.

Hopefully I'll have a chance to try cranking the idle timing up a bit today and move the tach wire back to the proper side of the coil, see if that makes any difference.
 
My opinion so far,...

The pistons are either stock or stock replacement, so that + that cam=low cranking psi.
mystery solved.

Second, the idle mixture screws, if I read right.., had no effect on the idle speed or quality....so=your probably idling off the mains.

If you were to raise the initial timing, you'd then be able to lower the idle speed screw down to the 800 rpm range and make the idle mix screws responsive again...btw what can make this worse..is that if you are in the mains...and the pv is rated higher than manifold vac....your drowning the motor in gas.
The added timing will also help low speed responsiveness where the low comp really hurts.

You may find yourself locking out the distributor at 34*....and it still starts...
 
The idle mix screws have been a lot more responsive now that I plugged the exhaust crossover holes in the manifold, and I've been able to get the idle speed lower, so what you're saying makes sense.

I also posted this over in electrical but maybe it's better off here since this is sort of the catchall thread for my issues:

Question time for the coil. I have 2 wires going to the coil, plus a blue/green one that I know is from the tach. One is thicker, black with a brown tracer. The other is thinner, black with a yellow tracer. The way it's been hooked up since I got it is:

Thinner black wire, tach, and condenser to coil +
Thicker black (brown tracer) to coil -

Now the book I have says thin black with yellow tracer to - and brown to +. Has my coil been hooked up backwards since I got the car? If so, how the heck did it run? These wires are definitely from a factory looking harness, they haven't been spliced in anywhere. Colors stay the same through a big 8-pin connector.
 
Oh wow.....black w/yellow goes to the coil -, it does sound like you have the coil wired backwards, switch it!

but 1st for the hell of it...test light the brown wire with the key on, if it lights...you do have them backwards..
 
Tested it, the thick black with the coil got 12v with the ignition on. How the hell was it running with a backwards wired coil?
 
Considering I've gone at least 2k miles on it with the coil wired backwards, I think my next investment will probably be a new coil.

Definitely definitely runs better with that fixed. Tuning is a lot more responsive so now it's just a matter of getting it dialed in and replacing anything that needs replaced.

On an unrelated note, this gives me a lot of confidence that the rest of the engine was built well...
 
Would anything have been messed up by having the coil leads reversed for so long? Ignition module for example? I'm thinking replace the coil but I don't want to just go throwing money around on parts that I don't need.
 
Try wiring it right and see how it reacts.

If the coil gets really hot still and or it still runs crummy, get another coil just because and start over using the same advice I and others gave you, you'll learn a lot.
Good luck
 
Is the big vacuum port on the rear of the carb plugged. It is in the center facing back under the bowl. Looking at the pick I didn't see a hose coming from it and usually it goes to the pcv valve. That could be your hissing sound and cause it to drop the rear cylinders. alot of guys forget to plug this port.
 
Oldmanmopar said:
Is the big vacuum port on the rear of the carb plugged. It is in the center facing back under the bowl. Looking at the pick I didn't see a hose coming from it and usually it goes to the pcv valve. That could be your hissing sound and cause it to drop the rear cylinders. alot of guys forget to plug this port.
Click to expand...

Excellent work, that port has been sitting wide open the whole time. DOH!

I'm kind of glad you didn't point that out for a while, though, or I might not have ever realized my coil was wired backwards.
 
Yeah, the coil I can blame on the last owner. This one was on me... gotta learn somehow!
 
Big thanks to everyone who helped me out in here. Took way to long to find two simple problems but I finally got a chance to start her up with that vacuum port plugged and man does she run sweet compared to before. Will try to get a new video up soon for comparison purposes, it's about as night and day as it gets. Still needs some more detailed ignition and carb tuning but I think the big stuff is fixed.
 
Glad you found it. I did the same thing with a new Edel 1405 (Carter 600 cfm) but figured it out pretty quick because of the loud whistle emitting from the engine.
 
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