Technical issue with 1958 chevy 283 (I hope she's not worn out)

Looking for some help. I have been helping a buddy with his 1958 Biscayne and I may have reached the end. The car (with around 50k original miles) had been sitting for quite a while at his family's house. The car is mainly stock with an edelbrock carb and intake. He picked up the car and drove it a little till it blew out an o-ring in the exhaust. It was replaced along with the fuel pump and he cleaned out the carburetor. The car seemed to run good for around 15 miles and started surging. He took me for a ride in it and it was surging bad with little power. He dropped it off at my house that day and I couldn't even get it to move into the garage. The next morning I looked in the carb and it was soaked with fuel. So I pulled it off and adjusted the floats, which fixed that problem. The plugs were fuel fouled, so I put in another set gapped at .035 (fuel dripped out of one of #8 cylinder when I removed the old one. It started right up and I pulled it in my garage. I checked the firing order, and the resistance on the coil, then set the timing at 4BTDC without vacuum ( I validated TDC on the balancer), set the idle at 700 and the dwell at 30. When I plugged the vacuum advance in (manifold vacuum, not timed), the timing didn't change. I checked the vacuum advance with a hand pump and it was functioning. I hooked up my vacuum gauge and the motor was only pulling between 5-8 inches and it was fluctuating. I took the car for a drive and it was surging pretty bad and didn't want to gain RPM up a small hill. I tried more timing, disconnecting the advance, lighter and heavier carb springs and it eventually fouled the plugs again. It doesn't seem to be burning oil. I did a compression test (Motor warm and throttle open)and got 95,107,95,104,107,101,102,100. My plan tomorrow is to throw a known good carb on the car and see how it does. Am I missing anything? Any other advice? This thing is driving me crazy and it has become personal.

 

5-7 inches of manifold vacuum at idle indicates plugged exhaust to me, what won’t get out inhibits what can come in

Old deteriorated muffler? Rats nest, ect.
Just my thoughts.

 

Do a pressure test on the pump. We used to get pumps putting out 3 times the specified pressure.

 

I recommend you get a thermal scan pyrometer and take temperature reading on exhaust outlet temp. from heads at header, this will indicate which cylinders are, or are not firing. A cold reading on one cyl. means a dud. You can use spit on your finger, but a cheap thermal pyrometer is more fun.

 

**** in the gas. Causing the carb to flood over. Causing the fouled plugs, poor performance ect.

 

For once all of the above are reasonably viable.
Trash from the tank breaking loose (especially with Eth****) and clogging up the carb.Is it plugging up filters or have you seen trash in the carb?
Exhust plugged up= What does it sound like when you stand behind the car and have someone gun the engine? Like a good exhaust what ever the sound or does it have a kind of a whistle? Anything except exhust blowing out the tail pipe when they gun it?
I can't remember what year they were on GM cars and don't remember if they were ever sold in the after market but back in the 70's we had trouble with laminated exaust pipes having the inner liner collapse. Usually after someone was rolling down the road and got the exhaust good and hot and then hit a puddle that caused the outside layer to contract and squeeze the inner layer for a bit. The inner layer then collapsed. My then boss at a Midas shop proved it to a customer in 1977 when he told the customer if the pipe wasn't collapsed inside he would put a whole exaust on the car for free. The guy was happy to pay for the exhaust when he saw the insides of the pipe.

Vacuum are usually a pretty good indicator of what is going on with an engine on fully Hamb Friendly engines that aren't radically modified.


Looking at the reading for late valve timing you might want to check for excess slack in the timing chain. That just costs a few minutes of time with no money spent unless there is a lot of slack in the chain. 50K on a stock engine that old probably means that it has the original timing chain and very likely a plastic gear.

 

The first thing I thought of was jumped time,,,,,,those vacuum gauge readings are fairly accurate .
Or,,,,it has a major vacuum leak ?
Even a vacuum leak doesn’t explain some of the symptoms he is describing .
I would check the cam gear,,,if possible .
But,,,,,,the blown o ring in the exhaust might offer a clue,,,,,,very possible it is a blocked pipe,,causing excessive back pressure,,,,and a blown o ring .

Tommy

 

I'm going with exhaust being plugged

 

Thank you everyone, you’ve given me some things to check. Do those compression numbers seem ok for a stock 283? I thought they were pretty low.

 

If you blew out an exhaust o-ring ? I'd say a blocked exhaust as well.

 

Stop running the engine until you determine if the oil has been diluted with fuel. The flooding condition you describe can allow liquid fuel into the cylinders, past the piston rings and into the crankcase. Does the oil feel "thin" between your fingers or smell noticeably of gasoline?

 

I had a similar issue with a stock 327 that was due to a new, faulty ignition condenser. I opened the points manually with the ignition on and it looked like an arc welder. Plugs were covered with soot and it was blowing out the tailpipes. A used condenser fixed the problem. Just another suggestion to consider.

 

Never seen an o-ring in the exhaust. Maybe you meant a donut gasket between the manifold and the exhaust pipe?

 

Sorry, yes that is what I meant.

 

Yes…A good example of something I learned long ago. Just because it’s new out of the box ,doesn’t mean it’s not defective… especially, electrical components I think….Having said that, I think I’m also with the “exhaust being plugged “ crowd.

 

If you have the carb flooding fixed, you might be surprised what changing the oil will do since it has a lot of gas in it.

 

In 1958, 50,000 miles was time for an overhaul. Your compression numbers are starting to indicate that, next is a leakdown test. What everyone has suggested is good solid advise, especially the exhaust being plugged. Try the easy stuff first but don't be surprised if it needs a rebuild. JMO

 

Couple of other things to check also (along with everything everyone else says), make sure the centrifugal advance is working and not sticking also check to make sure that the balancer marks are correct at TDC. Bring engine to TDC at #1 and check rotor and balancer.

 

Wow for the first time that I have seen, every suggestion applies to the problems at hand. It will be interesting to see what fixed it.

 

I’m interested.

 

I’ll let you guys know

 

Quick update. I pulled the exhaust and it was not clogged. I checked the fuel pressure and it pegged my gauge, then settled at 8psi. I’m off to get a regulator, new plugs, a fuel filter and a condenser.

 

Consider changing one thing at a time so we will all know which component if any, was the guilty party.

 

Far better than changing everything & learning nothing !

 

Yep, like Johnny Cash. One piece at a time.

 

I had some time today, so I hooked the exhaust back up, and changed the fuel pump back to the original. The car started right up and was idling well. It had a fuel leak, so I shut it down and will fix it tomorrow. I was talking to the owner, and told him that the vacuum gauge shows latent valve timing. He told me that his step dad (who was the caretaker of the car for a while) told him that it had jumped ignition timing and he moved every wire over one to fix it. Has anyone heard of an SBC jumping ignition timing without jumping cam timing? I think that I know what has happened here.

 

Not me. Me too!

 

I have had problems with fuel filters from china they fail internally and mess up fuel flow, so I went with a expensive wix filter, no problems after that

 

After changing the fuel
Pump, the car is running fine. I’m sure I could find something else, but I’ll give it back to my buddy. Thanks everyone for the help.

 

Did you do an oil change as well?