hi guys.. the Other day I was flogging my Powerwagon pretty hard , what else is new.. I was towing a 5000lb boat with the beast. I was going up and down a lot of 9 and 11% grades..it was hard pulling, but I really enjoy the sound of the slant at full throttle around 3200 rpm.. she performed like a champ.. I sold the boat at my dealership and my boss payed me to deliver it.. anyhow afterwards running empty around 2800 rpm on the highway.. I heard a rod knock sound.. it goes away under heavy throttle.. only hear it at light cruise.. which seems backwards to me.
Anyhow I was thinking back.. the one hill I pulled I was running like 3800 rpm sustained for a good 2 minutes.. it was like 80 outside.. truck was running cool.. i run 10-40 oil, truck hold 6 quarts, stock oil pump, nothing special.. the motor has 9.2-1 comp ratio, 4 barrell, head work, rv towing cam, only has about 40,000 miles on it.. I run it hard when I run it, and I like to hook heavy things to it and make my buddys uncomfortable..I was jsut looking for insight into what the problem maybe?? any suggestions or ideas.. I'm not gonna drive her until I get a game plan, or pull the oil pan.. you think I ran out of oil in the PAN?? can a stock pump, pump it that fast??

_________________
The worst mistake a boss can make, is not say "well done"

Are you sure it was a rod knock? or are you hearing detonation?
You say you hear this at 2800 RPM and light throttle. This is when the mechanical advance is near max from the RPM, and the vacuum advance is maxed out because of light load.

I have detonation problems with all my slants under this condition. It goes away by reconnecting the EGR system. You did not say what year or components your engine uses. Remember that when the emissions stuff was added to slants, they also redid the advance curves to work with the stuff.

The motor is a pile of differnt parts... 82 bottom end, converted to solid lifters, 74 head ported, stock valves, 74 distributer, no egr, and vacuum advance is unhooked...go ahead and Yell.. I've never noticed any difference either way?? I'm sure this is a bottom end noise.. I've single handedly blown up 4 slants now...I'm getting to know what a rod knock sounds like all too well .. as far as the vaccum advance is conerned.. I'm open to comentary on that.. I'd like to hear everyones opinion on unhooked vs hooked up thanks for the help as always...Dan

_________________
The worst mistake a boss can make, is not say "well done"

BTW... timing is set at 31 deg total.. with 93 octane fuel

_________________
The worst mistake a boss can make, is not say "well done"

Try to advance a li'l more the timing, like 36 or so total, initial 14 and hook up the vacuum advance unit, regulating the vac advance unit to fully tightened clockwise. (Use a 2,5 mm allen wrench)

Could it be a piston pin or piston slap making the noise?
A piston problem will make noise at light throttle.

What happens if you run heaver oil in it, try some 30 wt.
DD