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428 FE breathes Fire
I got my Contemporary a few weeks ago and have been trying to learn every detail, but without being the original owner I have some work to do. My first question I wanted to throw out there is how normal is it for a professionally rebuilt 1967 428FE to throw flames? It only happens when I let off the throttle and I've only noticed it from the right side. To give an idea, a few of them have been big enough that I can see it from the driver's seat. I know "people" say, "only a poorly tuned car throws flames" but I've seen numerous professional race cars do it. So, I've always doubted that logic. As long as it's not causing damage I don't mind it at all. :D I just don't want to ruin this as I plan to have it for a very long time.
Any ideas? |
Hey DonnieR32,
I hope the wedding plans are in going well. Just remember to say these words and you'll be fine. "Yes dear! As you wish dear" :p Flames in the pipes on lifting the throttle are normally due to unused fuel running through the pipes. This typically means your engine is running a little rich. Leaning it out might help to reduce the flame. Leaning it out too much however, could probably cause you more problems/damage than running a little rich. ie: burning valves, etc... Other, more experienced members will no doubt chime in here with a more thorough overview. Take care. |
I think you have an air leak between the header and side pipe. Mine does it too, only on the passenger side. Great way to scare away ricers who want to race you. Jim
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Or I heard it was excess fuel dripping into the exhaust pipe (previous owner) his approach was it's an old car, enjoy the show. |
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The previous owner had a similar answer, but we were discussing it via text message so, I posted here to get a more thorough answer.....guess it can't be all that bad. |
You likely have an exhaust leak somewhere and its allowing air to be drawn in on deceleration, creating a lean condition and the backfire. Its definitely not normal. I would look around the header-to-head gasket for black soot, and around the header to side pipe flange. If they are slip-fits that is likely the culprit spot for sucking in air on decel. It needs to be fixed because where there's inward suction on decel, there's a damaging exhaust leak on accel.
P.S. If it were excess fuel (its not) that would be even worse because that engine should have NO unburned raw fuel leaving the exhaust, period. |
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Defintely a slip fit air leak on decel. Had same problem. Fixed with a flanged set up . By the way use the Remflex gaskets. Tried all the others and the Remflex finally fixed theblock/ header leak. Now on for two years and not an issue. Others would last only a week or two
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I drove for years with no problems using slip-fit connections.
If the fit has worked loose over the years, why not just buy an expander and tighten thiings up? I've done this (though not on a cobra), worked like a charm, and was much easier, quicker, and cheaper than adding flanges. No doubt that adding flanges is the ultimate fix, but probably not the only satisfactory and workable one. Just my 2 cents. |
By all means if you can adjust or repair your slip-fits to correct the popping you should try. If you cannot confirm they are leaking, it might be worthwhile to check your timing and tuning.
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I'll do a once over....I mean the car shakes a lot so its not unlikely they could have vibrated loose.
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Don't know what color your exhaust is, but you may be able to see smoke/carbon leaving a mark where you have a leak.
I could see on mine. |
Donnie the CCX uses a slip fit as you've seen on your car. Make a (sharpie) line where the headers go into the sidepipes. The sidepipes are really easy to remove, two tabs on the slip joint and a rear hanger. If you take your headers off and try them one at a time in the sidepipes you will quickly see first off if they aren't going in far enough from your line and also if any have loosened at the joint. A good exhaust shop can expand them to get a good fit as suggested. If they aren't going on far enough I make tabs for the exhaust to replace the original style. You can give them a little snug up as needed to keep that joint tight. I use a 1/4-28 grade 8 screw through them with a mechanical locking nut. http://img171.imageshack.us/img171/3742/pipes028.jpg
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Mickmate,
What do you mean "If you take your headers off and try them one at a time in the sidepipes you will quickly see?" Maybe I"m not understanding, but how would the headers and sidepipes be placed together one at a time? I thought the sidepipe fit over the header... |
Maybe this is the culprit... this isn't the best picture, but you can sort of see the spacing.....
http://i112.photobucket.com/albums/n...bra/Header.jpg I checked the bottom where the header slips into the side pipe and it was on there fine. There may be some spacing between the two, but they're still overlapping. UPDATE: So I get to figure out if my exhaust manifold is 1-3/8" W x 2-1/32" H or 1-5/6" W x 2" H.... really? Seems to be a lot of soot at the block/header and a bit of space so I'm guessing it's there, according to the pic. Where the header meets the side pipe it has significant overlap and it looks pretty clean. I noticed some spacing where they meet up, but I don't know how snug their mating is supposed to be. Can't believe I have to take the header off just to measure the hole size for such a minimal difference. Guess I'm looking at getting one of these two depending on what I measure. http://catalog.remflex.com/PhotoGall...uctCode=RF3009 |
Here are a few shots of how my headers are shaped.
http://i112.photobucket.com/albums/n...a/IMAG0293.jpg http://i112.photobucket.com/albums/n...a/IMAG0294.jpg http://i112.photobucket.com/albums/n...a/IMAG0301.jpg |
Hey Donnie I like these they have a sealing ring pressed into them. Mr. Gasket 7164 - Mr. Gasket Copperseal Exhaust Gaskets - Overview - SummitRacing.com
The other common problem I have seen there on CCX's is the 1/4" flange plates that curl over where the bolts bend them. It leaves it leaking in between. Check the flange plates for flatness when you get it off. |
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