Took my 62 to the local station yesterday that has 92 octane ethanol free gas, filled it up as often before there and headed home via a short stretch of freeway. Wanted to check the speedo versus my gps at 70 mph. lots of traffic so I got on it pretty good to find a quick space in traffic to get to 70. Soon after that I took the next off ramp and noticed a different exhaust note it seemed on the driver side exhaust as i slowed down to the stop using the engine and downshifting to help cut my speed. Kinda like a burbling sound, maybe similar to a very low Jake brake sound a truck might make, thought for a second an exhaust clamp had come loose. At the stop the tach was reading about 150 RPM below normal. Taking off there was quite a bit of stumbling of the motor in first gear. Once underway things seemed better but not normal. Headed home did a few engine restarts in the driveway, RPM was a bit better but still low. While parked gave it several throttle pulls by hand in, no stumble just a normal response. Left and right exhaust seemed to have the same note and feel. However taking off again from a dead stop 2-3 times again, low RPM and stumbling trying to get underway in first. Of course my first thought since it had started 5 miles from adding 7 gallons of fuel was bad gas. However that seems more unlikely. Other things running thru my mind since i had this strange exhaust note on down shift compression was a valve maybe.

Anybody have any insight for me?

 

Check your distributor cap, carefully, for any cracks. Remove the distributor cap and check the rotor for any damage. Check to be sure both ends of all spark plug wires are secure...both at the distributor and the spark plug. Easy things first.

 

Start with Leif's advice first. Even today 99% of fuel problems are ignition problems. While sniffing around under the cap and assuming you have the original type breaker point ignition inspect the points. Your symptoms can result from a worn rubbing block which has closed the gap, alters the dwell and therefore alters timing. Same thing happened this spring to my 63 Ford. Low, hunting idle and no carb issue. Points were shot. Remember point wear takes place at the contacts but just as important at the rubbing block.

Dan

 

What type of carb?

 

Carter AFB is on it, engine is a mix. Block is a 1964 "RC" 250hp, top end is 1962 "RE" 340 hp. tag on carb is correct # for a 1962, dual point dist as well

 

Your problem probably doesn't need the amount of posts in response that you have. As I mentioned in my earlier post these problems tend to be ignition and not carburetor. Are you running a Stock points ignition?

Dan

 

Yes, stock distributor and points

 

Start with the suggestions from Leif and Dan. Report back.

 

Is it solid or Hydraulic cam? 340hp 327 with original solid lifter cam, that I have in my 60, had a rocker arm back off on a hard pull and ended having very similar symptoms

 

When a fella has a running problem like the OP states he has, and everyone piles on with what it could be, carb, fuel sock, bad fuel, pump, rocker arms and so on, it likely isn't helpful especially when a fella isn't a knowledgeable wrencher on a Chevrolet. Our best advice should always be start with the basic, simple stuff. Any car running breaker points that all of the sudden begins running badly should have said breaker points checked, reset, or replaced if the contacts are burned or the worn rubbing block has closed up the points. Once points are reset or replaced, and I would replace then just to have a fresh rubbing block, your timing should be reset. Points are consumable parts that are expected to be changed 12,000-15,000 miles. If you can't remember when they were last swapped out and timing reset, there's your likely problem.

I'm confident saying your points are likely shot. 10 minute $20 job in parts. Do that first and let us know.

Dan

 

Well finally getting back to my 62, back surgeon gave me the go ahead to resume some of my bending twisting activities so I ordered a set of plug wires and thought i would start there as well as go to a warmer plug as my driving is typically around town, points, rotor and cap only have a 1,000 or so miles on them and after examining them and looking the age of the wires I thought I should replace them as part of the trouble shooting process. In doing so i found my number #4 plug was fouled completely, all other plugs were pretty much the same color. I did a compression check with my compression tester on #4 and it pulled about 165 lbs, #6 was about 150 lbs. Any thoughts on the cause? I have not driven it since i replaced the wires and plugs due to weather. Just wanted to get some feedback as to the possible reason.

 

I'm going to guess that there is a lot of carbon on top of #4 piston increasing compression ratio. First inclination is a bad stem seal and easy enouigh to replace to see if it improves.

Dan

 

Possibly bad valve stem seal or worn valve guide. Won't talk about the oil rings. But, could be a bad plug or wire too.
I would clean the plugs and install the plug from #4 in another cylinder which shows good burn. Then check the wire with an ohm meter (VOM) and flex it while checking continuity. Also check the contact in the distributor cap. I have encountered bad new plugs that exhibited weak spark and thus more build up. If you can run the engine for a few more miles, then pull the plug from #4 and check for oil buildup you are seeing.

 

I had a plug that looked exactly like that one a few years ago. A bad valve guide was the culprit.

 

Here's where I'm placing my money

 

I agree Dan, valve seals and or guides are the most common problem with a SBC.
However, I rebuilt the 327 mouse in R66 with 59,000 miles on it as it was using a quart in 100 miles and I had 3 plugs which looked fouled like that. The compression on all 8 cylinders were 150+ and within 10% of each other and passed the leakdown test.
I assumed valve guides and took the heads to an old machinist. We found the guides within the GM serviceable tolerances and recommended I not waste my money with new guides. The valves had up to .002" wear on the stems. I replaced all 16 valves and added positive seals.
I pulled the pistons and found 3 pistons with stuck oil rings. The previous owner must have never serviced the engine and the car set for an unknown period before and after his death. The cylinder walls were also within GM serviceable tolerances for a re-ring. I put new moly rings and Clevite rod bearings in.
The engine now has 1,200 miles on the rebuild and has not used a drop of oil.
This was my first experience with stuck oil rings on a SBC, that is the reason I mentioned them to the OP. IF his engine has good compression on all cylinders and good leakdown results, I would try valve seals first, then pull the heads and investigate. There is always the possibility of a bad plug or plug wire which is the reason I recommend moving the plugs around first.

 

Excellent narrative, Ron. A map for the OP to follow..

 

Moving forward with the guidance received, I have new installed new plug wires and plugs and will give it a test drive and then do a plug comparison and likely move on to new valve guides if issue remains.

Just wanted to speak about the great info and help I have received on this forum, this is my first C1 in 40 plus years, for he past 20+ i was into vintage British and American motorcycles, but with knee and back surgeries that is a thing of the past. I remembered the day of driving my C1 and C2's and the fond memories I had in my 20's. So here i am at 71.

The forum has been a great resource, not sure if i would of solved my taillight / brake light issue if I had not read the articles on the steering column mechanism function and repair guidance.