74 not starting
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Joined: Nov 2005
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From: Perth
74 not starting
I know about the air, fuel and fire and as far as I can ascertain I have all three.
Some back ground. Was having a few problems with the rochester - acceleration and cruising. We don't have a "Lars" down under, but I found a semi retired mechanic who seemed pretty knowledgeable. On his test engine it ran like crape, once he had rebuilt it, it ran sweetly. While the carb was being rebuilt I swapped out the original starter with a high torque version. The vet has points so I put the coil wire to the 'S' post of the starter with a diode. Unfortunately she won't start.
SO there is a good spark on all leads arcing across a 1/4 inch easily. Each plug sparks well. Fuel is definitely getting to the cylinders with the plugs smelling of gas. Pressure testing cylinders they are all within 120-130 PSI. No evidence of coolant in the oil. I have a new battery in her. I was getting 8.1 v at the + side of the coil while cranking, by placing the coil wire from the starter on to the battery lead and running it through a relay it reads 10.2v while cranking.
She cranks over well and fires, but the firing sounds weak compared to when she was starting and running. I should imagine this is an easy fix, but I can't see the the trees for the forest anymore. Any suggestions would be greatly appreciated.
Some back ground. Was having a few problems with the rochester - acceleration and cruising. We don't have a "Lars" down under, but I found a semi retired mechanic who seemed pretty knowledgeable. On his test engine it ran like crape, once he had rebuilt it, it ran sweetly. While the carb was being rebuilt I swapped out the original starter with a high torque version. The vet has points so I put the coil wire to the 'S' post of the starter with a diode. Unfortunately she won't start.
SO there is a good spark on all leads arcing across a 1/4 inch easily. Each plug sparks well. Fuel is definitely getting to the cylinders with the plugs smelling of gas. Pressure testing cylinders they are all within 120-130 PSI. No evidence of coolant in the oil. I have a new battery in her. I was getting 8.1 v at the + side of the coil while cranking, by placing the coil wire from the starter on to the battery lead and running it through a relay it reads 10.2v while cranking.
She cranks over well and fires, but the firing sounds weak compared to when she was starting and running. I should imagine this is an easy fix, but I can't see the the trees for the forest anymore. Any suggestions would be greatly appreciated.
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From: SW Florida.
you say it has points. back in the day i would regap peoples points when i heard them cranking motor for 15 seconds before starting. what shape are the points in and how are they gapped? condenser. it may be 20 years old. you will see a spark that won't light gasoline on fire. plugs. probably gas soaked and now need stronger spark. pull the plugs. crank engine to blow out excess gas. clean or replace plugs. get points set correctly replace the condenser. pick up a can of starting fluid while buying points-condenser. of if you have some try that first. but gas fouled plugs will not fire starting fluid either.
Last edited by derekderek; Jul 25, 2020 at 09:16 AM.
Drifting
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1/4" spark isn't good enough. It should be able to jump at least 1". How long have the points been in there? Have you measured dwell?
Should be 28-32 degrees. Gap isn't accurate enough. If the spark is good enough, and you're sure it has fuel, then timing is a concern. Try to line up the damper mark at TDC, where is the rotor pointing? Should be #1 or 6
Should be 28-32 degrees. Gap isn't accurate enough. If the spark is good enough, and you're sure it has fuel, then timing is a concern. Try to line up the damper mark at TDC, where is the rotor pointing? Should be #1 or 6
Last edited by Mrvettenick; Jul 25, 2020 at 10:51 AM.
Le Mans Master
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
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Your mini starter has no small terminal for the yellow wire so leave it off for now.
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From: Southern MD
So the R wire is the one that feeds 12V to the coil during cranking. Once the engine starts then the coil is fed juice via the ignition circuit through the ballast resistor. If the car has good spark during cranking and sounds like it is starting but die when the key is returned to the run position. Jumper around the ballast resistor and see if it will start. The ballast resistor is located on the fire wall and looks like a ceramic rectangular piece with a wire connector at each end and a mounting screw at the top . I had that happen once on my 71 Vette and I couldn't figure it out. I talked to an old knowledgeable guy about it and he figured it out without even looking at the car. A couple of dollars later and she was running great.
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From: Perth
Thanks for the replies. The spark plugs, points and condenser were replaced about a year ago and due to work and rego restrictions I've only put about 200 miles on her. This morning have rechecked dwell - 30, leads will arc across an inch gap. Haven't changed timing and on number one compression is pointing to number one terminal. correct firing order as well
Still hunting for the ballest resister at this stage
Still hunting for the ballest resister at this stage
Le Mans Master
Joined: Aug 2006
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From: mount holly NC
2025 c3 ('74-'82) of the Year Finalist - Unmodified
2019 C3 of Year Finalist (appearance mods)
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