I'm about a hair away from taking this car to the shop and saying fix it regardless of cost. It is a 61 Comet with a 144 and a Holley 1904 single barrel. I replaced the ignition point, caps, etc and rebuilt the carb. I should have left it alone! It ran fine before I tinkered with it. Now, it will run, rough, but when let off the gas it shuts off and sounds bad. Last week the carb caught on fire and knocked over my two year old running in the house to get the extinguisher. The carb does a little backfiring every once in a while and I have to turn the mixture screw way too far out. I think the real problems started when I rebuilt the carb. I replaced the ignition stuff first. I can't remember how it ran after just the ignition. There are no vacuum leaks that I can see. The points, dwell, timing, plugs, look to be right. I believe the float is set correctly. I replaced the fuel pump thinking that is the problem and it's not. Now I have this &*%$ leak that I can't stop. I'm extremely frustrated as you can tell.
There is something seriously wrong with my engine
- Thread starter Pete W
- Start date
Mercury Mike
Famous Member
Alright, slooooow down. First off, verify that your harmonic balancer is in the right place, and your timing is good to go. Once you have your initial timing set to about 10-12*, with the vacuum to the carb disconnected and unplugged, you can get to the carb. Turn the fast idle screw as far out as you can without the car dying, adjust the idle mixture screw, and then adjust the fast idle screw after you have it giving the right A/F ratio, and you will be good to go once you get that idle. However, I have been in your boat before. I had a baaaaad thump, and I figured it had to be the carb. I was wrong, it was the timing. I messed with the carb for weeks, and then I read all the posts about "check your timing!". I checked my timing, it was WAY off, I fixed it, and it ran like a top. I should have left it alone, though, and just changed the timing. I did sooo much to that carb..... LOL You'll get it, just stick with it.
Usually fire means a serious timing problem, either ignition or cam but would also be possible that the thing is dumping WAY too much fuel.
Refresh my memory and or link to your previous posts, seems like we were working on your problems but I dont remember the specifics.
Refresh my memory and or link to your previous posts, seems like we were working on your problems but I dont remember the specifics.
I'm not sure if this helps but I checked my float measurements in my carb this afternoon and when I opened it up it was bone dry. Can fuel get into the venturi bypassing the float reservoir? It had been about a week before ran the car but the fuel evaporated. When I readjusted the float height there was no fuel leaking in when I raised the needle.
A bowl full of fuel shouldnt evaprate in a week unless it was really really hot, even then I would expect some sludge or something.
johnnyzoom
Well-known member
Many of your symptoms sound like mine after putting a new carb out of the box in. When I rebuilt it, the float needle was stuck and it was missing a ball check.
Can you go right through the ignition one more time, first? Backfiring through the carb suggests possible retarded timing.
Start by double-checking you have TDC at the compression stroke. Then, confirm the plug wire order and test each one's resistance as you reinstall.
Check your coil for continuity on both primary and secondary sides. Test for a good ground between the distributor housing and the block, and confirm your motor's ground strap is well connected. Turn the ignition to "On" and check voltage at the coil.
Also test the condensor's capacitance, and confirm dwell is within specs. don't rely on points gap; dwell is far more accurate.
Confirm each plug gap is around 30-35 thou, and the insulator nose is not covered in carbon. A spell of running badly can exacerbate problems here.
Now start the car up, and check timing with a strobe. With the vacuum advance line plugged, look for 10-12° advance at idle (say 600 RPM) on a warm motor. Set this in Drive, with the hand brake firmly in place, headlights on highbeam, wipers running (remove the arms if need be), and heater/radio on. If it's a manual, leave the electricals on but set idle below 600 in neutral.
Any further problems at this point are not with the ignition system. You can also do a compression test on the warmed-up motor.
I'd suggest buying the little (1½") fuel gauge sold by places like Summit - it's about $18 and the metal adapter with hose barb each end and a 1/8 NPT thread amidships is another $7-$8. Easy to splice between the pump and carb.
Now, we can go back to the carb and pinpoint any trouble sources by fuel circuit - idle, transition, main and power.
Cheers, Adam.
Start by double-checking you have TDC at the compression stroke. Then, confirm the plug wire order and test each one's resistance as you reinstall.
Check your coil for continuity on both primary and secondary sides. Test for a good ground between the distributor housing and the block, and confirm your motor's ground strap is well connected. Turn the ignition to "On" and check voltage at the coil.
Also test the condensor's capacitance, and confirm dwell is within specs. don't rely on points gap; dwell is far more accurate.
Confirm each plug gap is around 30-35 thou, and the insulator nose is not covered in carbon. A spell of running badly can exacerbate problems here.
Now start the car up, and check timing with a strobe. With the vacuum advance line plugged, look for 10-12° advance at idle (say 600 RPM) on a warm motor. Set this in Drive, with the hand brake firmly in place, headlights on highbeam, wipers running (remove the arms if need be), and heater/radio on. If it's a manual, leave the electricals on but set idle below 600 in neutral.
Any further problems at this point are not with the ignition system. You can also do a compression test on the warmed-up motor.
I'd suggest buying the little (1½") fuel gauge sold by places like Summit - it's about $18 and the metal adapter with hose barb each end and a 1/8 NPT thread amidships is another $7-$8. Easy to splice between the pump and carb.
Now, we can go back to the carb and pinpoint any trouble sources by fuel circuit - idle, transition, main and power.
Cheers, Adam.
When I get the car going by pushing on the accelerator the car runs far. It just won't idle. I haven't removed the distributer from out of the car I just replaced the cap, points, etc. I've checked the timing and it's fine. There is no balabcer just the pully. I've checked and rechecked the plugs and they're in the right spot. The more I think about it this all started when I rebuilt the carb.
I've noticed that the more the mixture screw is out the easier it is to start but it is out much further than the manual says it should. I also have to turn down the slow idlw screw until it stops, which isn't right. Nothing in the carb is clogged or blocked because I just cleaned it.
I've noticed that the more the mixture screw is out the easier it is to start but it is out much further than the manual says it should. I also have to turn down the slow idlw screw until it stops, which isn't right. Nothing in the carb is clogged or blocked because I just cleaned it.
A
Anonymous
Guest
Pete W":365f573r said:
Try raising the float level
Hi,
Thanks for your suggestions I really appreciate it.
I'm gong to take your advise and make absolutley sure it's not the ignition before a take out the carb and rebuild it again. I have a few question.
Addo suggested:
"Confirm the plug wire order and test each one's resistance as you reinstall"
How do I do this? I have a multimeter but am not sure how to use it.
"Check your coil for continuity on both primary and secondary sides. Test for a good ground between the distributor housing and the block, and confirm your motor's ground strap is well connected. Turn the ignition to "On" and check voltage at the coil"
How do I do this with this? Do I use a multimeter?
"test the condensor's capacitance"
How do I do this?
I've done the straw trick on the compression stroke to check TDC but when I did it the rotor button was not pointing diertly at the #1 spark plug but about a quarter inch before. Is that OK. I'll check to make sure the timing mark is correct on the pulley. I haven't taken the dizzy out so everything is pretty much the same as when I bought the car. The dizzy is 180 out with the number one spark plug pointing toward the bottom(if you were looking down at the dizzy from the drivers side). The only way to keep the engine running is to press the accelerator. I guess my wife can do this while I chekc the timing.
Thanks,
Pete
Thanks for your suggestions I really appreciate it.
I'm gong to take your advise and make absolutley sure it's not the ignition before a take out the carb and rebuild it again. I have a few question.
Addo suggested:
"Confirm the plug wire order and test each one's resistance as you reinstall"
How do I do this? I have a multimeter but am not sure how to use it.
"Check your coil for continuity on both primary and secondary sides. Test for a good ground between the distributor housing and the block, and confirm your motor's ground strap is well connected. Turn the ignition to "On" and check voltage at the coil"
How do I do this with this? Do I use a multimeter?
"test the condensor's capacitance"
How do I do this?
I've done the straw trick on the compression stroke to check TDC but when I did it the rotor button was not pointing diertly at the #1 spark plug but about a quarter inch before. Is that OK. I'll check to make sure the timing mark is correct on the pulley. I haven't taken the dizzy out so everything is pretty much the same as when I bought the car. The dizzy is 180 out with the number one spark plug pointing toward the bottom(if you were looking down at the dizzy from the drivers side). The only way to keep the engine running is to press the accelerator. I guess my wife can do this while I chekc the timing.
Thanks,
Pete
OKay... think about it this way.
the ONLY way for the mixture in the intake manifold to ignite is if the spark fires on a cylinder that has its intake valve open.
Now if we assume for a second that your cam hasn't slipped on it's gear and that one of your valves isn't stuck open... this means that either you have a plug wire going to the wrong cylinder or your timing is too far advanced or retarded.
The rotor being 1/4" away from the post at TDC indicated that the timing is WAY retarded. (that's if the rotor is 1/4" Before the post ... the rotor spins CW)
the ONLY way for the mixture in the intake manifold to ignite is if the spark fires on a cylinder that has its intake valve open.
Now if we assume for a second that your cam hasn't slipped on it's gear and that one of your valves isn't stuck open... this means that either you have a plug wire going to the wrong cylinder or your timing is too far advanced or retarded.
The rotor being 1/4" away from the post at TDC indicated that the timing is WAY retarded. (that's if the rotor is 1/4" Before the post ... the rotor spins CW)
With the battery disconnected, and mouldymeter in hand:
Set the meter to ohms, and test with a probe on each end of each lead. Write down the values as you go. You will (should) not see identical numbers, but a generally similar trending.
To test the coil, first stick one probe in the centre socket and the other to the bracket mounting bolt. You should see between 6K and 9K ohms for an original coil. Now put one probe each on the little terminals (after disconnecting the negative one from the dizzy). Expect a lot less ohms. The difference between them is what multiplies the voltage.
To test your grounding, keep the meter set on ohms and just test resistance between the block and battery negative terminal. It should be one or two ohms at most.
Reconnecting the battery and switching on the ignition, set your meter to DC volts. Test with one probe on the little positive terminal of the coil and one probe on the battery negative. Expect less than ten volts. Turn off the ignition again, for now.
Remembering the firing order goes clockwise when viewed from outside and above, and is 1-5-3-6-2-4, check the cap's wire hookups to be sure this is faithful to plan. Number one is at the front closest to the radiator. Your timing light is hooked to number one plug lead.
Set the meter to ohms, and test with a probe on each end of each lead. Write down the values as you go. You will (should) not see identical numbers, but a generally similar trending.
To test the coil, first stick one probe in the centre socket and the other to the bracket mounting bolt. You should see between 6K and 9K ohms for an original coil. Now put one probe each on the little terminals (after disconnecting the negative one from the dizzy). Expect a lot less ohms. The difference between them is what multiplies the voltage.
To test your grounding, keep the meter set on ohms and just test resistance between the block and battery negative terminal. It should be one or two ohms at most.
Reconnecting the battery and switching on the ignition, set your meter to DC volts. Test with one probe on the little positive terminal of the coil and one probe on the battery negative. Expect less than ten volts. Turn off the ignition again, for now.
Remembering the firing order goes clockwise when viewed from outside and above, and is 1-5-3-6-2-4, check the cap's wire hookups to be sure this is faithful to plan. Number one is at the front closest to the radiator. Your timing light is hooked to number one plug lead.
