MILD THUNDER

I considered pulling heads, swapping the lame cam out, and doing headers at that time.

The vortec heads have very small chambers, around 100cc if i recall. I see engine quest now makes a replacement head for these engines. Might be something to fool with come next fall.

She doesnt burn a drop of oil or smoke on startup after sitting for long periods. Guessing the guides and seals are still good.

SB

Have you ever tried reducing that dumb (my words, lol) .060" gap down to something like .040" ? Your motor, as you know, does not have COP, so that large gap is quite hard on everything else ignition related. I wonder what heat range those stock plugs are ? I only know / relate heat ranges by the old AC #'s, not the newer one's.

MILD THUNDER

You might be on to something Scott.

I replaced those plugs with delco R44LTS6 that I do believe they come gapped at .060, and honestly, can't remember if I gapped them at .045, or left them alone, Its been a few years now. The plugs probably have 15-17k miles on them, along with the wires, cap & rotor, etc.

I have no idea where I got the R44LTS6 number from. Probably was from Rockauto. But just broke out the owners manual for the truck, which lists the replacement spark plug, as a AC Delco, 41-932. Apparently, from some googling, that number has been superceded to 41-933, which is a Irridium plug. The ones in my engine now, are standard plugs.

IDK what the delco plug heat ranges translate to . I know the R44, would be a step hotter than your typical plug in say a 454 merc engine? Dont they usually run a "43" heat range?

Either way, I think i am gonna order some fresh plugs, and a new delphi cap and rotor kit.

MILD THUNDER

Went to Ac delco website, shows for my truck, original equipment replacement, is 41-979 ac/delco, which is a double platinum, .060 gap. Also lists the R44LTS6 as an optional plug.

Should I order the 41-979's, or stick with a standard plug? Maybe a slightly cooler plug?

Definitely gonna try the .045 gap. .060 is a bit much, or seems like it.

SB

Does the 6 stand for .060" gap ? If so, I'd get the LTS without the 6. Shouldn't have to bend ground strap as much to get to the .040"

And yeh, a 200 ton Dually is a lot of load by itself, so I'd go with the 43's.

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On to another possibility - by chance have you seen if these knocks where result of trans shifting a little to quick (a little too low rpm) or if trans does not downshift quick enough ? Or lock up clutch a applying a little early ? You see where I'm going with this.

MILD THUNDER

Yes, i believe it does stand for .060. The "6" that is.

I can go 0-60 with no knock retard. Only on the hwy, when i floor it from 60mph and hold it there, in 3rd gear. I believe last check i had KR at 3250rpm .

It will be interesting to see what it does pulling the 38 in the hills near loto with the a/c crankin when its 95 degrees out !

F-2 Speedy

It might take a dump....lol you'll need to turn the AC off, what HP is that thing making.

MILD THUNDER

Last summer it pulled the hills fine there, but didnt have the scanner looking at knock retard either. Last time we came down, had the cruise set at 70, and only one hill on hwy 54 knocked it down to 65ish. Im sure it was pulling some timing though!

F-2 Speedy

That pretty impressive, whats your rig weigh ...........

MILD THUNDER

Truck and boat 20k lbs. Boats around 13-14 on trailer depending on fuel