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Discussion Starter #1
BACKGROUND: I just rebuilt my 302 inside my apartment and it fired up on the first try :) It was my first rebuild and I was very very careful about bearing clearances and rod cap torque, etc. I spent several months reading and researching to make sure I got it right. I converted it to a roller cam and lifters so I bought the 302 H.O. rebuild kit from FlatlanderRacing.com and specified that it was a truck instead of a car. A side effect of this is that it's now a 351 firing order so it idles a little rough because the injector timing is still 302. I've done 3 oil changes since I first started it and the engine only has about 350 miles on it.

After timing it and other miscellaneous adjustments I can't figure out what this noise is coming from the engine. I pulled off the serpentine belt and made a video of the sound.

http://www.youtube.com/watch?v=MQx2qPAhvKs

It kind of sounds like if you were to strap a stiff wire brush to a wheel and spun it rapidly. Like a scraping noise.

FYI: I know I've probably got exhaust leaks on the passenger side because I snugged up the header before I got some of the bolts started so I'm missing 3 bolts where the header pipes made too much of a bend to start the bolt. I can hear those exhaust leaks with a tube to my ear and they just sound like little farts.

This noise is much louder and seems like it's coming from the front of the engine. When you're standing in front of the motor it sounds like it's coming from the driver side but if you move to the driver side it sounds more like it's coming from the front of the engine. The noise gets faster as engine RPM increases.

There doesn't seem to be any power issues except it seems like it has less torque than a truck should have going uphill but it screams on the interstate. I think this is due to a combination of the H.O. cam, C6 tranny, and maybe gears with the 33" tires. I have no idea what gears are in it since the door sticker is gone.

I've put a poor man's stethoscope (long breaker bar) to my ear and touched various parts of the motor but it all sounds like it's humming nicely. I can't hear any loud knocks coming from the engine so I don't think it's knocking.

Would you be able to hear a bad bearing with a stethoscope?

Any sort of noise makes me really nervous now that I've been intimate with every inch of the engine. If it's a bearing or a valve train issue I just want to resolve it right away before I do any more damage.

Thanks for any input as I'm excited to get the Bronco back on the trail.
 

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Discussion Starter #2
Bump?
 

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it sounds like the exhaust leak sucking in air. cant really hear a popping noise just a sucking noise with the leak.
 

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Discussion Starter #4
Thanks. I'm gonna try and button up the known exhaust leaks this weekend and see what it sounds like after that. It's tough though because the driver side is torqued down as tight as I can get it but I can still wiggle the gasket with my finger. I wonder if I should double up the gaskets?
 

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Maybe the harmonic balancer or its pulley isn't seated properly, torqued incorrectly, etc? Did you install a new one with the rebuild? Maybe the outer ring has spun free or it needs a repair sleeve where it passes through the timing cover.
 

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Discussion Starter #6
I put a new sleeve in that came with the rebuild kit. (this thing right? http://www.competitionproducts.com/images/CPC18.gif )

Everything on the timing cover seemed like a good fit and I did a lot of reading before pressing on the balancer with a rented tool.

I stuck a stethoscope up to the timing cover and I can't hear any periodic banging, just a steady moan like everywhere else on the motor.

More and more this is sounding like exhaust leak from the headers. I've heard you can put baby powder around the gasket to see if it blows off. I think I'll try that this weekend.
 
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