BloodyKnuckles Posted March 23, 2009 Report Posted March 23, 2009 I drive my car alot...alot. So I've been expieriencing backfiring through the carbs more and more lately. It happens when it wants to not just under load. It can be winding out and begin to pop, lugging in 3rd it'll pop or just normal driving it'll pop. So what could be causing this? Is it possibly the vacuum advance? Timing? Points? What?? Any bit of guidance here would be greatly appreciated as I'm getting ready for another long distance run to Austin, Texas in a month and would love to get this thing running right again. BloodyKnuckles Quote
Don Coatney Posted March 23, 2009 Report Posted March 23, 2009 Check your distributor cap and/or rotor for cracks. Quote
greg g Posted March 23, 2009 Report Posted March 23, 2009 also point gap and the wire from the coil terminal to the points inside the dist. Normspeed looks to be heading to Austin for the Lone Star roundup, during the same time frame, leaving from Florida, maybe you guys could meet up along the road somewhere, kinda a misery loves company deal. Quote
randroid Posted March 23, 2009 Report Posted March 23, 2009 BloodyKnuckles, It could also easily be a sticking intake valve, but not to sound as the harbinger of bad luck it could easily be remedied. Backfiring through the carb intermittently and, if I interpreted your post correctly, under varied conditions is easily explained by the good advice already given and because they're a lot easier to do than checking the valves I'd suggest doing them first, but if that doesn't do it check the valves. I really like Marvel Mystery Oil for cleaning an engine while maintaining great lubrication properties, but I hesitate to dilute the engine oil on a regular basis so I use it as a solvent. I've never removed the valve inspection panel from inside the RF fender but it is such a brilliant alternative to hanging upside-down from a sky hook to adjust the valves that I'm going to do it just because I want to experience such simply practical engineering. Block the car, yank the wheel, pull the plate, open the valve covers and take a look at the valve stems. (In order to be able to simply touch the battery of my wife's 2004 Dodge Stratus I need to remove a section of the front wheel well that's made of and held in place by flimsy plastic that looks like it's aching to break, so what I'm suggesting is experiencing that which was made to get a job done rather than being an excuse for BS 'engineering'.) Do the valve stems or springs look gooey or crusted? I prefer not to scrape interior engine parts because unless I'm going to boil the block I imagine chunks of carbon seeking havoc to wreak, but a solvent can do wonders, and that's where the MMO comes in. Use it on a rag or paper towel and see how much junk you remove. Kerosene would be initially faster and is safe to run through an engine, but finish with MMO for that protective lubrication. UNDER NO CIRCUMSTANCES SHOULD YOU USE WD-40 TO CLEAN ANYTHING INSIDE YOUR ENGINE! I like and use the product but it's chemically engineered to break-down petroleum-based products and must be used with that in mind. I hope it's just the distributor cap, but when was the last time you poked your head inside your engine? You'll feel better starting your trip. -Randy Quote
BloodyKnuckles Posted March 23, 2009 Author Report Posted March 23, 2009 Thank you guys for the responses. I will look into the cap and rotor first. I have put over 28,000 on them since I replaced them last. I will replace them anyway. I'll also look at the point gap and coil wire. Randy, Thanks for taking the time to reply. I do appreciate your input. BloodyKnuckles Quote
Normspeed Posted March 23, 2009 Report Posted March 23, 2009 The vac advance is easy to check, and might be the problem. Also, the plug wires, even though they are probably the wire core type. Easyto check with an ohmmeter. Might see you in Austin...? Quote
radioguy7 Posted March 24, 2009 Report Posted March 24, 2009 UNDER NO CIRCUMSTANCES SHOULD YOU USE WD-40 TO CLEAN ANYTHING INSIDE YOUR ENGINE! Will the WD-40 police come after me if I do??? I've used WD in and around my engine many times with no adverse affects to my engine. I did not pour it in my crank case, but if used sparingly will cause no harm at all. Quote
randroid Posted March 24, 2009 Report Posted March 24, 2009 radioguy7, I use WD-40 on and around my engines quite freely but never where it might be ingested inside the engine. Some people aren't aware of its properties so I thought a caveat would be in order. If you disagree with me then, well, there's something rewarding to be found in saying you've just rebuilt your engine. (That's a joke; I'm not trying to pick a fight.) -Randy Quote
Beallrite Posted March 24, 2009 Report Posted March 24, 2009 The problem sounds like its NOT base on fuel demand or delivery .I'd check the distrubtor for cracks moisture or crabon build up .next vac leak (tighten down those carb nuts) and then sticky intake valve . Quote
Beallrite Posted March 24, 2009 Report Posted March 24, 2009 I spray wd-40 on the the bricks in my lobster pots .lobsters really love that stuff ! P.S that may be illegal too Quote
MacGyver Posted March 24, 2009 Report Posted March 24, 2009 I went through this same scenario last fall. In my case it turned out to be a stuck intake valve. Let's hope for something easier... Quote
radioguy7 Posted March 24, 2009 Report Posted March 24, 2009 radioguy7,I use WD-40 on and around my engines quite freely but never where it might be ingested inside the engine. Some people aren't aware of its properties so I thought a caveat would be in order. If you disagree with me then, well, there's something rewarding to be found in saying you've just rebuilt your engine. (That's a joke; I'm not trying to pick a fight.) -Randy if you say so Quote
BloodyKnuckles Posted March 25, 2009 Author Report Posted March 25, 2009 Guys, I really appreciate all the help. I removed the cap and inpected it. There were no signs of cracks or build up on the electrodes. The rotor looks good also. Not sure about the points though. They look like like the have a light colored powder on them. I'm not sure if that's normal. I also adjusted the timing and it eliminated some of the popping. I may try some sort of "mystery" oil too see if there is a stuck valve maybe it'll work it's self loose. Thanks again, BloodyKnuckles Quote
randroid Posted March 25, 2009 Report Posted March 25, 2009 BloodyKnuckles, The white colored powder is, in its most basic definition, a form of rust caused by them doing their job is but something that can also cause them to stick, thereby allowing the plugs to fire when they shouldn't and igniting fuel in the intake manifold to ignite prematurely. That would make intermittent firing through the carb. Wouldn't it be sweet if that were the culprit! The most common method of repairing them is replacement, but if you want to get into the mindset of our forefathers who built these cars you can get a 'points file' from NAPA for cheap and clean them yourself. The trick is to make sure you keep the surfaces parallel to each other and my most successful method has been to gently squeeze the file between the points and draw it easily back and forth holding the ball of the file with fingers held perpendicular to the file. It works, sometimes better than others, and should give you an idea if that's where the problem lies. If it helps you might want to replace the points anyway because it's a sign that the points are beginning to fatigue and when they fatigue so does their spring, which would cause them to bounce and make the fuel fire back through the carb. radioguy7, it isn't I who says so, it's WD-40 who says so. Jeez! -Randy Quote
greg g Posted March 25, 2009 Report Posted March 25, 2009 Sure just go to NAPA and get the youngest counter dude and tell him you want a points file, the watch the expression on his face..... Quote
BloodyKnuckles Posted March 29, 2009 Author Report Posted March 29, 2009 So far the only thing I really did that day was adjust the timing. That day on the way home it still popped through the carb. I just got done driving it for about 3 hours and not one pop, not one! What in the hell?? BloodyKnuckles Quote
greg g Posted March 29, 2009 Report Posted March 29, 2009 double check the vacuum advance, it might be hanging up or lagging. Quote
BloodyKnuckles Posted March 30, 2009 Author Report Posted March 30, 2009 What is the best way to check the vacuum advance? BloodyKnuckles Quote
Plymouthy Adams Posted March 30, 2009 Report Posted March 30, 2009 timing light and a hand held vacuum pump with hopefully a vacuum guage attached..the guage is nice but not a necessity..be sure that the advance will hold steady with vacuum applied... Quote
BloodyKnuckles Posted March 30, 2009 Author Report Posted March 30, 2009 Unfortunately I don't have a timing tab on my timing cover so a timing light won't work but I can use a vacuum gauge. Where should I hook it up? At the VA? BloodyKnuckles Quote
Plymouthy Adams Posted March 30, 2009 Report Posted March 30, 2009 you can check you advance by putting a temporary timing tape..anything that has marks and will reflect the light for easy reading...check the book for the amount of advance at X vacuum...and yes the connectionis directly at the VA Quote
greg g Posted March 30, 2009 Report Posted March 30, 2009 connect the vacuum pump to the tube from the carb to the vacuum advance dashpot. with the dizzy cap off, pump some vacuum and observe the breaker plate, it should move, and hold positio till yo release the vacuum. Run number 1 up to TDC and put a tire crayon or chalk mark on the timing cover and on the pulley or damper. Then you can use you timig light and the pump, should advance the timing when vacuum applied. Quote
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