Fixed one issue another popped up
- Thread starter jct
- Start date
ok, sounds like an extreme lean condition. you are most likely on the right track with a vacuum leak. i'm not sure where you got the condenser from, but most new ones are junk. you may want to swap the old one back in to confirm that there are no issues there.
That low vacuum reading and it still running is interesting. Unless somebody angle-milled the heads (for more compression) or flat-cut the head's without doing a similar cut on the intake side, to compensate, then I suspect nothing really wrong on the intake manifold/cyl head interface. You'll know when you get the manifold back off and look at the contact areas on the intake valley pan gasket's beaded areas around the ports.
For that matter, you could go ahead and take the intake off now and see what it looks like. Which might indicate now if that's the issue, rather than something else. Especially if the car is not really driveable now.
My one experience with a leaking power booster was that it would hiss loudly when the brake pedal was depressed and the engine would miss at the same time.
Keep us posted,
CBODY67
For that matter, you could go ahead and take the intake off now and see what it looks like. Which might indicate now if that's the issue, rather than something else. Especially if the car is not really driveable now.
My one experience with a leaking power booster was that it would hiss loudly when the brake pedal was depressed and the engine would miss at the same time.
Keep us posted,
CBODY67
Rather than look for specific vacuum gauge levels, pay more attention to what the needle does. Remain rock solid stable? Wander a bit from a middle value? Have a drop when one cylinder misses? Etc.
In a time when "dwell tachs" were big, huge devices that only serious garages tended to have, plus new car dealerships, vacuum gauges were what "common people" tended to use. As things progressed, the electronics of the dwell tachs became less expensive and smaller, such that hand-held versions became available, in about the mid-to-later 1960s. Which is when we came to know about "percentage of full-scale error" in such things. The compact (works in the cup) dash tachs were in the middle 1960s, too, as prior Corvettes and such had cable-driven tachs from the distributor.
EACH has their place, but BOTH can yield better results for diagnosis when used together.
Vacuum levels are not always "absolute", either. Vacuum levels can drop with altitude AND probably barometric pressure, a bit. Which means that 18" at sea level might well be 17" at 1000ft elevation, for example. It's all about spring pressure against a diaphram, which can mean things in the "meter" are variable.
Just some thoughts,
CBODY67
In a time when "dwell tachs" were big, huge devices that only serious garages tended to have, plus new car dealerships, vacuum gauges were what "common people" tended to use. As things progressed, the electronics of the dwell tachs became less expensive and smaller, such that hand-held versions became available, in about the mid-to-later 1960s. Which is when we came to know about "percentage of full-scale error" in such things. The compact (works in the cup) dash tachs were in the middle 1960s, too, as prior Corvettes and such had cable-driven tachs from the distributor.
EACH has their place, but BOTH can yield better results for diagnosis when used together.
Vacuum levels are not always "absolute", either. Vacuum levels can drop with altitude AND probably barometric pressure, a bit. Which means that 18" at sea level might well be 17" at 1000ft elevation, for example. It's all about spring pressure against a diaphram, which can mean things in the "meter" are variable.
Just some thoughts,
CBODY67
jcslocum
Member
I love the economy gauge!!! Installed a few for customers during the first gas shortage.
John Kirby
Active Member
The vacuum gauge looks reasonable. What does it look like when you open the throttle? It should drop and smoothly rise back up as the engine picks up rpms. If it jumps around you have a vacuum leak or valve issue. That would normally show up at idle.
I'm leaning toward an ignition problem.
When you step on the gas more fuel/air enters the engine and a high voltage spark is required.
1. If you have a voltmeter measure the voltage on the coil high side terminal with the wire removed from the starter relay. Should be battery voltage when the key is in the cranking position and around 8-9V or so when in the run position. That would rule out the ballast.
2 Is the coil securely bolted to the engine? Ground issues are also a possibility.
3. Is the ground strap at the back of the engine installed correctly?
4. Verify the plug wires are in the correct firing order. 1-8-4-3-6-5-7-2.
5. Remove the distributor cap and closely inspect the rotor and cap center terminal. I once had a cap installed wrong and damaged the terminal where it contacts the rotor. Ran very poorly.
6. The condenser could also be the problem.
I'm leaning toward an ignition problem.
When you step on the gas more fuel/air enters the engine and a high voltage spark is required.
1. If you have a voltmeter measure the voltage on the coil high side terminal with the wire removed from the starter relay. Should be battery voltage when the key is in the cranking position and around 8-9V or so when in the run position. That would rule out the ballast.
2 Is the coil securely bolted to the engine? Ground issues are also a possibility.
3. Is the ground strap at the back of the engine installed correctly?
4. Verify the plug wires are in the correct firing order. 1-8-4-3-6-5-7-2.
5. Remove the distributor cap and closely inspect the rotor and cap center terminal. I once had a cap installed wrong and damaged the terminal where it contacts the rotor. Ran very poorly.
6. The condenser could also be the problem.
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