Thread: 355 sbc question about exhaust sound (need some help here!)

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After cooling off a little im gonna give this another chance. comment that has all the info on it is on page 5 with a link in it.

I didn't hear anything bad.. but, the video is at the wrong end of the car!

OH, welcome to CHR too. Good to see you here and hope you enjoy the site and the folks.

Your profile shows New York. the plates show Canada...

I agree with Mike, put your camera/mike up front, focused on the engine. The exhaust sounds OK with a healthy idle, but the exhaust note drowns out any engine sounds that might point to problems. Also, after your 45 second clip it rolls into a longer clip about a red '82 which is a different car, right?

Welcome to CHR.

Sounds good to me, but since you don't know much about the internals I think I'd keep the shift point at 5 grand or below.

Welcome
JMHO, it sounds like back pressure, possibly a leaky exhaust gasket/joint, or a loose muffler baffle..

Glad you enjoyed Denny,
Maybe just my ears, but I'm hearing a rattle on the reversion...

JMHO, but I think that what you're hearing is harmonics and the baffling in the mufflers.

Originally Posted by Tie-355

But the question i have is If the car should sound the way it does when reved to around 5000 rpm.

As the above question asks,
To me it sounds like a little back pressure as it comes off throttle, it doesn't mean a bad thing. However, my old ears hear a slight rattle at reversion. Thus the suggestion to check for a loose baffle and/or small exhaust leak, both of which are easy to do.
Not trying to be funny, certainly no disrespect intended, and it may just be harmonics as suggested...

And I believe that resonators behind the mufflers would probably cancel some of it out though I sure wouldn't want to do that.

Originally Posted by 34_40

I didn't hear anything bad.. but, the video is at the wrong end of the car!

OH, welcome to CHR too. Good to see you here and hope you enjoy the site and the folks.

Your profile shows New York. the plates show Canada...

K thank for the reply I would get a another vid of the engine bay while it was running but it is tucked away for the winter because we got a couple feet of snow here lol. and as for the fact ti says new york when it asked for where i was it said sate and there aren't states here in canada..................

Originally Posted by DennyW

36-sedan...That's funny...

Like NTFDAY says, sounds good.

Engine sounds sound enough. Even on the banks, nice lope, and has good response. Sounds healthy... Pipes look fair as cylinder burn goes. A hair on the rich side, but that is ok.
As far as the rpm's to go to...well, you need to go until just before the pull stops, and grab another gear. Winding out as far as it will go, is not to your benefit. I would say 5000 rpm's is about it from the cam I hear in there. Shift before it runs out of pull (steam), otherwise you are just plain wearing it out, and have a chance of blowing it... If you can, find out the exact cam that was installed, and then look it up, and check, when the power curve tops out.
Ken has it, keep it at 5000, and don't push it.

rspears, youtube does that on videos...They go to the next one in the list automatically.

ps: Aytime you run it up past the safe rpm zone, you now put it in the go or blow mode...You only do that if---you have a lot of cash bet on the win...

K thanks that is what i thought for shift points rpm wise. The power curve feels like it peaks between 5000 and 5300 because around 5500 you can feel/hear it lose some power so thats why i kept my shift points around that 5000 - 5300 mark. As for the cam i will never know any of the internals unless i pull it apart and seeing as i dont trust myself pulling apart a $10,000 motor just yet i don't think i will know for a while. (its one thing if its a shitty honda motor i got for free lol!)

Originally Posted by 36 sedan

Welcome
JMHO, it sounds like back pressure, possibly a leaky exhaust gasket/joint, or a loose muffler baffle..

Im surprised you could hear that in the vid!!! The front right header comes a little lose on its own every so often so i need to tighten it once every 1 or 2 weeks until i can afford to buy 2 new hooker headers.

I have experienced it many times, it's not enough of a leak to make it backfire (yet), but the added exhaust pressure will certainly make the baffles unhappy...

Son, before you begin reading what I wrote here, don't think that I'm picking on you. I'm just bein' REAL with you and attempting to help prepare you for dealing
with other folks who might try to take advantage of your inexperience.

I'm 17.... but there is still alot I dont know.

Really? I'm 73 and believe me, there's a ton of stuff that I don't know yet.

355 full roller motor. The whole motor and exhaust system has been redone (with what i dont know)

First off, you don't know that it's a 355 until you research the casting number and suffix number on the block. It could just as easily be a 262, 265, 283, 305, 307, 327 or 400. Secondly, you don't know that it's a roller motor until you disassemble it and eyeball the roller lifters for yourself.

I just know that the receipt the older man i bought it from said it was 10 grand for the crate motor and the parts that went into it.

The receipt that you saw doesn't necessarily belong to the motor that you bought. It could be from another motor that the fellow built, or from a friend's build, or from who-knows-where. Your motor could be one that I listed above with a flat tappet Thumpr cam in it to make it lope. Trust me here son, if this was a $10,000 motor, it wouldn't be signing off at under 5500 rpm's.
Most any of the fellows on this forum have the knowledge and expertise to build you a 500 horsepower / 500 ft./lbs of torque motor for under $5,000, just so you know.

It said state and there aren't states here in canada.

No, but there are 10 provinces and 3 territories to choose from. The whole idea is to know approximately where you live so the answers we give will be intelligent ones (hopefully).

As for the cam i will never know any of the internals unless i pull it apart and seeing as i dont trust myself pulling apart a $10,000 motor just yet i don't think i will know for a while.

Again, I doubt you have to worry about it costing $10,000. I'm pretty sure the seller was yankin' your chain just to jack the price up and make the sale.
If you'd like to research the motor as far as what the casting number and suffix number will tell you, look at these photos....
Here's the block casting number, on the driver's side rear of the block....
http://www.speednik.com/files/2013/0...asylum-com.jpg

Here's the suffix number that will tell you what application the motor was intended for from the factory...it's located on the passenger side of the block just ahead of where the head ends and is adjacent to the passenger side top water pump bolt. It may be hidden behind an alternator or other accessory piece...
DSC09740A.jpg Photo by dan1s | Photobucket

Pull either driver's side or passenger's side valve cover and inspect the head for a casting number. This will tell the tale....
http://www.speednik.com/files/2013/09/stockCastNo.jpg

If you don't feel confident pulling a valve cover, at least try to match the end casting symbols and let us know what you have....If the motor has aftermarket heads on it (which it damned well should have even if the builder spent only $5,000), the manufacturer's name will be stamped into the metal at the end of the head and can be seen easily without removing anything...a magnet held against either head will tell you whether the head is cast iron or aluminum....
http://image.hotrod.com/f/31706454+w...ds_test%2B.jpg
http://www.onedirt.com/photos/data/5...Marks_copy.jpg
http://www.crankshaftcoalition.com/w...casting_id.jpg

It would also be helpful to us if you'd give the description and part numbers off the intake manifold, carburetor and distrubutor. Photos are worth their weight in gold....

.

Originally Posted by Tie-355

Im surprised you could hear that in the vid!!! The front right header comes a little lose on its own every so often so i need to tighten it once every 1 or 2 weeks until i can afford to buy 2 new hooker headers.

Before you go buyin' headers, there are a couple of different ways to stop header bolts from coming loose. If that is what's happening, let us know, we can share info to help keep the header bolts tight.