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Fuel System, Performance Mods, Engine, Fuel System, Coupe, Convertible, Hatchback, Truck, Sedan, Wagon
#360 of 399 Re: Carb still bogging [crampton1998]
Jun 10, 2009 (12:25 pm)
I need to add that, if you decide to replace the distributor, please consult with me first about an appropriate brand and model. Many performance distributors would not be suitable in your application; for a wide variety of reasons. So it is important to know which ones would be a good choice for use in your truck.
#361 of 399 Re: Carb still bogging [zaken1]
Jun 11, 2009 (8:04 pm)
Replaced the plugs and wires, plugs are AC Delco R34S set to a 0.35 gap, nobody had the Autolite #85 or AP85 that you suggested and these were the crossover plugs, the wires are Borg Warner magnetic suppression wires that you suggested. Engine starts and runs fine but has a constant slight backfire while running. The fuel level is getting low and I didn't know if this "backfire" was caused by it running low on fuel ?
#362 of 399 Re: Carb still bogging [crampton1998]
Jun 11, 2009 (9:46 pm)
I'm glad you replaced the plugs and wires. The backfire you hear could come from a mistake in the firing order when the plug wires were installed in the distributor cap. The firing order should be 1-8-4-3-6-5-7-2; reading clockwise. If you find the wire to #1 cylinder, and then follow the next wire that is clockwise in the cap; it should go to #8 cylinder; the next clockwise wire after that should go to #4 cylinder; the next wire should go to #3; and so on through the order listed above. The cylinders on the drivers side are numbered 1-3-5-7 going from the radiator to the firewall. On the passenger side they are numbered 2-4-6-8 going from the radiator to the firewall. If the firing order is correct; the idle mixture screws might be set too lean. I don't think low fuel level in the tank could cause such a backfire.
If the cam in your engine is radical enough; it might be normal for the engine to sound like that; but it is very difficult to know without listening to the engine. I will say that while my nephew was learning about tuning cars, I once went with him to a shop that deals in race parts. While we were there; a pickup drove up, and sat there with the motor idling. My nephew turned to me and said "That truck is missing." I listened to it for a minute, laughed and then said "That truck is not missing; it has a racing cam in it. That's the way engines sound when they have a big cam in them!"
Did you compare the timing on #1 and #6 cylinders? How did that turn out?
#363 of 399 Re: Carb still bogging [zaken1]
Jun 12, 2009 (9:26 am)
Once again you were correct, I had the firing order set in this order 1-8-4-3-6-5-2-7, I swapped the 7 and 2 wires and it eliminated the backfiring. I won't be able to do the timing check on the 1 and 6 cylinders until Sunday due to obligations at a new job Friday and Saturday.
#364 of 399 Re: Carb still bogging [crampton1998]
Jun 12, 2009 (11:39 am)
Sounds like you've really started cookin!!!
#365 of 399 Re: Carb still bogging [zaken1]
Jun 14, 2009 (3:26 pm)
Cylinders 1 and 6 are firing correctly and all voltage and vacuum pressure are at the proper specs. Went for a test drive and everything ran excellent with no bogging or loss of acceleration and the engine runs better than I could ever imagine. Thanks for all of your help.
#366 of 399 Re: Carb still bogging [crampton1998]
Jun 14, 2009 (4:27 pm)
Well, it couldn't have happened without your trust, patience, curiousity and dedication!
Now that you have been through this experience, I'd like to repeat a comment I made in this forum (post # 257) a few months ago. If you had read it when we first began this dialogue; would you have believed it???
"In over 30 years as a professional mechanic; I consistently found that about 85%-95% of the cars which the owner believed had a carburetor problem really had an undiagnosed ignition problem. That is a shocking statistic. I hope you all find it helpful in your own work."
#367 of 399 Re: Carb still bogging [zaken1]
by Mr_Shiftright HOST
Jun 14, 2009 (5:28 pm)
I lost track of this ongoing discussion. What was it that turned out to be the problem?
#368 of 399 Re: Carb still bogging [zaken1]
Jun 14, 2009 (5:36 pm)
I just took the wife for a drive and it ran great until we pulled into a parking space and it died. Had to floor it to get it started and it had a rough time idling. Is the carb flooding ?
#369 of 399 Re: Carb still bogging [Mr_Shiftright]
Jun 14, 2009 (7:29 pm)
A bad ignition switch, points, improperly gapped plugs, bad wires, had a resistor wire and ballast resistor going to the coil, negative battery terminal that was improperly grounded, I think that I got everything.