225 Engine miss and low oil pressure

Good evening. I finally got around to getting the '46 out yesterday but it seems that winter took it's toll. There's a slight miss at idle which isn't too big a deal but from off idle through the rest of the band it starts missing pretty bad and backfires when throttle is returned to idle. I changed the plugs/wires and ran some carb cleaner through with a fresh tank of gas but it didn't seem to help. There's no noticeable smoke but it does smell a bit like unburned gas. I reied advancing and retarding the timing a bit incase the mark was off or the gears were work but it made no appreciable improvement. I gave it an oil change before starting it up and once it was running I noticed it's got 20lbs of oil pressure cold and hot at idle. Revving up the engine the pressure only rises to 22-23 lbs which worries me a bit. I tested with another gauge which confirmed the same reading. At this point I'm thinking there may not be enough pressure to keep the lifters pumped up which is leading to the miss. I replaced the oil pump late last year and I remember it working OK but maybe the bypass has gotten stuck?. Any thoughts on this would be greatly appreciated.

 

Yeah, you'll hear the lifters before you hear anything else. If it isn't an *obvious* clacking noise*, I'd start with looking at the oil pressure, if that's low, go pick up a new high volume pump (not high pressure, HIGH VOLUME), in the grand scheme of things 10 psi per 1000 rpm is fine. High pressure isn't going to do you anything. I just wish we all had access to a flow meter. What is flowing through the motor is far more important than at what pressure that oil is moving at....

 

What was your oil pressure last year when it was running right?

If it is backfiring returning to idle from higher revs, it sounds like timing or ignition. You mentioned you changed your plugs and wires but what about points and distributor cap? Condensation or cracks in your dist. cap could also cause those symptoms.

 

"There's no noticeable smoke but it does smell a bit like unburned gas"

Sounds like a carb issue to me. If it sat over the winter the fuel probably evaporated out of the carb and left some junk where it shouldn't be. I would check the tubes on the venturies. Make sure all the little holes are not obstructed.

 

They may be 2 unrelated issues. I'd be willing to bet the diaphram on your accelarator pump swole up from sitting in the new E10 or E15 gas. I was having the same problem and the carb guy put in 3 different pumps untill we found out the old school leather ones were not affected by ethanol

 

Thank you for the advice so far! I had not replaced the cap and rotor yet. So I picked them up today for a 66 CJ-5 with delco distributor ($15 for both). I ran into a bit of a snag here though, The cap does not fit properly. I included a picture of the 2 caps. The one on the right is from the jeep and the one on the left is the new one.


The cover location hits the vacuum advance housing so it won't sit level and the retention screws can't hold it down. The cap that came off the jeep has delco stamped in the plastic so I believe I asked for the right part. I took the one I got back and asked to see another one, which was the same as the one I got. Could this be a symptom of being made in China or is something amiss here? Here's a picture of the distributor. Maybe it's not a stock vacuum advance?


I picked up a rebuild kit for the carb so I'll get started on that in the meantime. I just did one last summer too...

 

I'm finding lots on HEI but this appears to be a points system. I'm fine with looking for the answer but don't know what keywords I'm needing to find it.

 

Ok, I returned the cap and and asked the guy at O'Reilly and they only list the one model I got. Autozone has 1 model for a CJ5 Universal and 1 for CJ5-A. The 5A model they can't even get. NAPA is closed now but I guess I'll check with them tomorrow.

 

Bwd c169

 

Hmm. After doing digging through this PDF http://www.nosmopar.com/DELCO.pdf I came across the picture of the 67-69 cap part (1110376) which looks like the right spacing for mine. Autozone says they can get it as part number DR982. Perhaps the PO got the year wrong on the engine?

Looks like google might have found your old thread with part numbers here: http://www.earlycj5.com/forums/showthread.php?74716-Delco-distributor-cap&p=807950#post807950

 

Had the very same problem as described above. The correct distributor cap for your 225 is NAPA # RR189