Is my engine snarling at me?

[ascdesigns]

I've been searching and reading through a number of posts and can't seem to find one that matches the sound my engine is making. When I accelerate (aka under load), it sounds like there's a low-pitched knock (not detonation which I understand tends to be higher pitched) from about 1500-3500 rpms. At higher rpms, the knock might still be there but the intervals are so close together and other ambient noises drown out the knocking.
I'll try to describe the knock: it sounds like someone is hitting a railroad tie with a 3lb sledge, if that makes any sense. There's no loss of power thankfully, pulls strong as ever. Gas mileage is the same as usual, between 16 city-21 hwy.
This has been making the noise for a while, but maybe because it's winter I can hear it better? I thought it was an exhaust leak but everything's tight in the pipes/manifold.
Piston slap? Wrist pins? Bad mains? Are the 3.0 Vulcan's just noisy/snarly engines? Should I just shut up and drive the snot out of it?

Other notes about my '98 Ranger:
New Autolite plugs/wires
Fresh 5W-30 oil and filter
All other fluids replaced in past two months
Been switching between 85, 89 and 91 octane (I live at 5000ft hence the lower octane levels)

Thanks!

Al

 

[trxusrngr]

I had sumilar noises with my 93 3.0 when i first bought it. I did two seperate things one afternoon and it disapeared 2 years ago and never came back. But maybe it was coincidence!
1.) Pulled the main vacuum line off the intake manifold and fed the damn thing som sea-foam!
2.) noticed my heat sheilds on my cats were making noise, so i just took a chisel and hammer and beat on the shields till they contacted the cat, making them tight again!
Good Luck!

 

[ascdesigns]

Thx - I'll check the heat shields but it does sound more like an internal knocking. I should have mentioned that I did seafoam the heck outta my engine right before I replaced my plugs.

- Al

 

[locovaca]

My Vulcan ticks/knocks until the oil thins out, and it's definitely noisier than my old 2.3 even when warmed up. Not saying there's nothing wrong, but they definitely aren't the quietest engines in the world.

 

[ascdesigns]

Yeah, I think I'll just drive it and stop being too anal about the noises. If it implodes well, ce la vie...