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post #1 of (permalink) Old 08-29-2004, 01:15 AM Thread Starter
 
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Broken cat killing milage?

I borrowed my cousin's sawzall and cut the cat off my bronco(figuring it was probobly fried plus I don't need it anyway) and when it was off I looked inside and everything was all in pieces and just moving around in whichever way I moved it [img]images/graemlins/shocked.gif[/img], is it supposed to be like that? common sense tells me no, anyways, how much could that have been killing my milage? [img]images/graemlins/confused.gif[/img]

PS, I now have no exhaust, just the y, talk about loud! [img]images/graemlins/grin.gif[/img] but oddly no matter how high I rev the motor there is no backfire [img]images/graemlins/cool.gif[/img]
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post #2 of (permalink) Old 08-29-2004, 02:59 PM
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Re: Broken cat killing milage?

NO! All you should be able to see from either side is a mesh pattern, and it should be one solid piece. Hit it with some re-bar a few times and it should all drop out the end. Definitely will pick up power since those pieces are probably getting pushed sideways and blocking the cat output.
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post #3 of (permalink) Old 08-29-2004, 06:47 PM Thread Starter
 
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Re: Broken cat killing milage?

Thanks muddy, that's what I thought, and the plan is to hollow it out but I probobly won't put it back on there unless I can't pass inspection in Febuary, but the guy I go to never checks it anyway, I'm gonna get some pipe and run the exhaust out in front the right tire like I had it till I can go have dual exhaust put on it, and if it's too loud I'll throw a muffler on there (which I'm sure I'll end up doing)

my next question is, someone mentioned having to rejet my carb since I have no muffler or cat, something about it running too rich or lean, I've been running around with no muffler for two years now, is this true? I get like nine miles to a gallon
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post #4 of (permalink) Old 08-29-2004, 11:11 PM
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Re: Broken cat killing milage?

I've never heard that, but there might be some merit to that since I do know that you have to reject a 4wheeler carb if you add an exhaust snorkel to it. I was getting a pretty steady 8.5 mpg highway or city before my exhaust work and now I get 10.5 city and almost 12 highway. Obviously I have EFI so I don't have to rejet anything, but I guess you can try it and if your mileage still sucks then you can experiment with carb work, or play it smart and swap to EFI [img]images/graemlins/cool.gif[/img]
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post #5 of (permalink) Old 08-29-2004, 11:57 PM
 
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Re: Broken cat killing milage?

Certinally you could try just re-tuning your carb to take advantage of the free-er flowing exhaust. Use this

http://www.superford.org/registry/ve...=17585#content



To help you tune it right into the ballpark. Works gangbusters on my Mopars with distributors.

Good luck

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post #6 of (permalink) Old 08-31-2004, 11:24 AM
 
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Re: Broken cat killing milage?

Since when do you have to reject a carb because of no muffler..... [img]images/graemlins/chair.gif[/img] [img]images/graemlins/spank.gif[/img] [img]images/graemlins/beach.gif[/img]
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post #7 of (permalink) Old 08-31-2004, 02:00 PM
 
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Re: Broken cat killing milage?

It's a motorcycle thing

That's what all the motorcycle world believes and they're telling their car buddies it must also be so, but it ain't always so.

True you change the balance bigtime when you run open headers and a lot of cars don't run right and backfire. In my experience there is enough room in a stock carb's settings to allow you to re-tune without having to re-jet.

If you change cams, port the heads, put on high lift rockers or alter the timing and/or compression drastically then yes you'd have to re-jet a carb, but he says his doesn't even backfire so he's gotta be in the ballpark and pretty close to what the engine wants IMO

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post #8 of (permalink) Old 08-31-2004, 04:51 PM Thread Starter
 
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Re: Broken cat killing milage?

</font><blockquote><font class="small">In reply to:</font><hr />
It's a motorcycle thing

That's what all the motorcycle world believes and they're telling their car buddies it must also be so, but it ain't always so.


[/ QUOTE ]

You've hit the nail right on the head. My uncle is a motorcycle guy and the only person in the world who ever told me that I'd have to rejet after removing the muffler (which I did two years ago) and converter cause of no backpressure would cause it to run rich or lean (he couldn't make up his mind which).

If all goes well with my new job I'll be getting a 79 F250 from my cousin and the 460 and D60 will be going into the bronco (if he hasn't found a buyer by then). If it's gone then I'm just going to get a remaned 400 to put in so I wouldn't have messed with the carb till then anyway, was just curious, thanks for the info guys, you've been a big help as always. [img]images/graemlins/40BEER.gif[/img]
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post #9 of (permalink) Old 09-01-2004, 02:49 AM
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Re: Broken cat killing milage?

Havack, it's an Atkins diet thing, you wouldn't understand [img]images/graemlins/chairfall.gif[/img]
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