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| Backfiring... Not Any More! http://www.international2cvfriends.com/forum/viewtopic.php?f=7&t=1296 |
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| Author: | JRW_91 [ February 6th, 2010, 4:05 pm ] |
| Post subject: | Backfiring... Not Any More! |
i do love the look on passengers faces when they thing we're being shot at, untill they work out its actually the car! Poppy hence why i called her this, Backfires, sometimes its just a raspy burble, sometimes its like a bomb! she only backfires when you let off and the revs come down, is this a problem, or is it something simple like valve clearances need adjusting? i've never done valves before so its something quite new to me athough looks fairly simple judging by the haynes manual! something else, i believe this is a recon engine, which has also had pistons and barrels done at somepoint by totally 2cv! This engine isnt the original, and its also had pistons and barrels at somepoint, it idles smoothly, feels good and strong low down, and mid range power is great, really pulls through the revs from 2k to 4k after 4 it doesnt pick up much at all! |
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| Author: | Russell [ February 6th, 2010, 4:15 pm ] |
| Post subject: | Re: Backfiring! |
Manifold leak. That's why my car does it anyway. |
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| Author: | hjbharry [ February 6th, 2010, 5:56 pm ] |
| Post subject: | Re: Backfiring! |
is it a standard exhaust?? mine pops and bangs all the time, best rolling down hill no throttle in third I LOVE IT!! |
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| Author: | Rumble602 [ February 6th, 2010, 8:23 pm ] |
| Post subject: | Re: Backfiring! |
Excessive backfire could be a condensor on the way out - but from your symptoms I doubt it. |
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| Author: | JRW_91 [ February 6th, 2010, 10:41 pm ] |
| Post subject: | Re: Backfiring! |
not the condensor Aidan, was backfiring on the old one, and its still backfiring on the new one! how do i check the manifold for leaks? would it be leaking around the base of the inlets and outlets or like a fracture in a pipe? once we've got settled down etc, we'll have the rockers off and check the valve clearances, if its still backfiring after that, i'll swap over the carb and manifold from Lily's original engine as i know thats a goodun! |
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| Author: | ken [ February 6th, 2010, 11:09 pm ] |
| Post subject: | Re: Backfiring! |
Joe, valve clearances don't usually have any influence over whether a car backfires on the overrun. What does cause this problem is a leak (or leaks) in the exhaust system, the closer to the exhaust port the leak is located, the more frequent the backfiring. Best way to trace an exhaust leak is to use a trick shown to me at Mondello by Roy, many years ago. Get hold of a metre or so of clean windscreen washer tubing, park one end of that in your ear then, with the engine ticking over, move the other end around every location the exhaust may leak. This will locate any leaks with pinpoint accuracy. ken ( Probably worth checking and adjusting the valve clearances anyhow, as it's something that's often neglected. If you're going to be driving the car hard, I'd recommend setting the clearances at 0.25mm exhaust and 0.20mm inlet. ) |
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| Author: | JRW_91 [ February 6th, 2010, 11:33 pm ] |
| Post subject: | Re: Backfiring! |
Thanks Ken, i dont know about a meter, but i'll see what i can find, and believe me, its extremely loud, sometimes its just a bang, other times its a consecutive rasp of bangs and pops! i have to admit i love the rally car sound, although passers by with dogs probably dont! 
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| Author: | JRW_91 [ February 6th, 2010, 11:39 pm ] |
| Post subject: | Re: Backfiring! |
hjbharry wrote: is it a standard exhaust?? mine pops and bangs all the time, best rolling down hill no throttle in third I LOVE IT!! haha yes harry, well it came with silencer and van pipe, but i had to remove them and fit my straight pipe down the side for now  now all i need is another swan neck, silencer and van pipe, some flexipipe and im done 
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| Author: | bertiewhite [ February 11th, 2010, 4:40 pm ] |
| Post subject: | Re: Backfiring! |
Gay_Joe wrote: hjbharry wrote: is it a standard exhaust?? mine pops and bangs all the time, best rolling down hill no throttle in third I LOVE IT!! haha yes harry, well it came with silencer and van pipe, but i had to remove them and fit my straight pipe down the side for now now all i need is another swan neck, silencer and van pipe, some flexipipe and im done Joe, I've got a silencer if you're going to Firkin? PM me if interested? |
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| Author: | JRW_91 [ March 3rd, 2010, 8:59 pm ] |
| Post subject: | Re: Backfiring! |
Right replaced the Left cylinder head, brand new gaskets, valve clearances done, timing doneno more blowing, no more popping  i did like it  i know i need to let the engine "settle down" etc before expecting lightening performance, but with the new bigger valve clearances, it doesnt seem as good! they are as ken suggested, 0.25 exhaust and 0.20 inlet, obviously i know shes not a race car, but i feel performance was better before! |
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