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Discussion Starter #1
I have a blown injected deal that I had a set of lemons headers on with a slip in silencer and changed over to a set of zoomies with slip in silencers that I did some re work to so they could handle a some rpm with the headers I was running a 140 main pill. Now with the zoomies its burning up the pipe after a hard pass then back down to say 3000 rpm I have leaned it out 3 times now. I just changed the pill over to a 155. Does this sound correct? Or should I be looking at somthing else Im not seeing? Plugs look dark and oil is still clean. So I cant be too far off
 

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Red Blooded American
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From the limited information I can see a couple probable causes.
* First, and foremost, the changing of exhaust shouldn't effect the fuel mixture, only the end performance of the engine.
* If it didn't do it with the tuned headers but does with the zoomies, it could be more the effect of time. Your pump could be loosing it's efficiency and you need to compensate with decreasing the flow back to the tank with a smaller pill.
* Lastly, we've all had a header reddening issue at one time or another due to retarded timing. You may also need a bit more timing.

This is by no means a complete explanation but a simple observation given the snapshot info given.

I just noticed your pill change admission and that could be a major problem in and of itself!
 

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Village Idiot
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WOW, about a thousand different things are running through my mind right now. One thing that comes to mind is are the silencers restricting flow enough to increase the exhaust pressure and thus increasing the temp( by holding the hot exhaust there longer). The second thing is that you leaned out your motor. That will greatly increase your exhaust temps and could very well be helping to cause the problem. (I have seen engines cook a set of headers before because they were overly rich, but that was on carburated gas engines FWIW). Timing could be an issue, but based off of your experience with the headers I don't feel that would be the culprit (just off the top of my head anyway).

One other thing that is bouncing around in my head (being that my head is empty it has lots of room to bounce around) is that depending on the efficiency of the headers they may have been helping to scavenge more fresh air from the intake than the zoomies and thus also helping to cool the exhaust. Anyway, those are just some thoughts from a moron. I am sure some of the experts might have more valid info, and I sure would love to hear what they have to say so I can learn also.

Paul
 

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CANT RE MEMBER
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O shit it's a jet............my bad

I'm kinda interested in where this thread goes,
i run into the same problem, not running any silencers or mufflers, 2 1/2 on both sets of headers, and it runs fat with the zoomies, i just change the tuneup with the different headers, i figure the back pressure makes the difference, i could use a little info here also??
 

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Discussion Starter #5
Well I checked the timing tonight and found that it was at about 29 to 30 degrees. So somehow I lost about 5 degrees of timing. I belive I had it at 35 degrees locked out. I changed it and the sound of the motor came to life. even sounded better at 40 but that is too extreme I feel. I will try to take it out the next warm day and see what happens now.
 

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Village Idiot
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I'm kinda interested in where this thread goes,
i run into the same problem, not running any silencers or mufflers, 2 1/2 on both sets of headers, and it runs fat with the zoomies, i just change the tuneup with the different headers, i figure the back pressure makes the difference, i could use a little info here also??
If you are running fatter with the zoomies then the headers are helping to get more air in. The zoomies are showing their inefficiency. I am a believer that zoomies are best suited for all out blown stuff and believe that mild to moderate blown stuff can still benefit from a properly designed header. Then again, I am not saying this from experience, just from personal theory (that may be WAY off).:p

Paul
 

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Just another Wannabe
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1,200 Posts
There you have it. Two ways to lean out an engine. Increased timing and less fuel. Looked like you fattened it up by taking timing out, and that is why it wanted less fuel for the optimized burn.
Let us know what happens next time out. (But put that fuel back to it to start with, just to be safe.)
 

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Village Idiot
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Well I checked the timing tonight and found that it was at about 29 to 30 degrees. So somehow I lost about 5 degrees of timing. I belive I had it at 35 degrees locked out. I changed it and the sound of the motor came to life. even sounded better at 40 but that is too extreme I feel. I will try to take it out the next warm day and see what happens now.
Congrats of finding something amiss. That should bring things around some. I guess that shows how much I know as I even stated that I did not think your timing would have moved just from installing zoomies.:)sphss It pays to check everything. Good luck, and make sure to fatten it up before getting on it.

Paul
 

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Boat Nut
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Flattie... make sure you change your pill back before you go mash the gas, would not want to be too lean with the added timing.
 

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What the hell!!!

If you are running fatter with the zoomies then the headers are helping to get more air in. The zoomies are showing their inefficiency. I am a believer that zoomies are best suited for all out blown stuff and believe that mild to moderate blown stuff can still benefit from a properly designed header. Then again, I am not saying this from experience, just from personal theory (that may be WAY off).:p

Paul
YOUR RIGHT, AFTER I POSTED IT DAWNED ON ME, THE MOTOR I HAVE IN IT RIGHT NOW DOESN'T HAVE ENOUGH..OOMPALUPAS...TO PULL THE BIG TUBE ZOOMIES (its a spare out of my 33 coupe):)bulb THANKS FOR YOUR OPINION, JOHN
 

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Village Idiot
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YOUR RIGHT, AFTER I POSTED IT DAWNED ON ME, THE MOTOR I HAVE IN IT RIGHT NOW DOESN'T HAVE ENOUGH..OOMPALUPAS...TO PULL THE BIG TUBE ZOOMIES (its a spare out of my 33 coupe):)bulb THANKS FOR YOUR OPINION, JOHN
John, that was just my opinion (which may always be proven wrong with hard facts) so take it with a grain of salt. (Heck, with my info it may take the whole dang shaker of salt).:)sphss

Paul
 
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