ProfEd

iTrader: (1)

Hey guys,
I recently put on a new set of heads (PRC stage 2.5 5.3's), cam (Torquer v2), LS7 lifters, LS6 oil pump/ LS2 timing chain, Comp Trunion kit, and some pushrods.

When I initially ordered the parts I read many places to go with 7.400" rods, so that is what I ordered. I did not check with a checker tool and I had quite a bit of clacking. I pulled those rods back out and ran the stock rods, which are 7.380" (I don't know why I hear so frequently that stock is 7.400"...that is NOT correct, at least for my LS1). With the stock rods I had less noise but still more clacking of the lifters than I was happy with.

I finally used a Comp pushrod checker tool and came up with 9 turns for proper length. That would give me 6.800" + (9x0.050) = 7.250. I then added 0.075" for the preload on these LS7 lifters and came up with a proper length of 7.325". I ordered these up and installed them this past weekend.

I still have a very very faint clacking noise, but I think it is simply the nature of this camshaft, basically just the standard typewriter noise.

*** My problem is that as I am revving through 1500-1900 rpm range I get this whizzing/whirring sound. It does it "very" faintly at other rpms, but it is noticeable in this range. It is also noticeable when I let of the gas and the engine decelerates back through the rpm band. It is somewhat of a gentle, even swishing type noise, almost to where it sounds like a squeak, but not that high pitched. Something like "wsshhhhhheeeeeewwwhhhhh" as I rev or let off through this rpm range.

The engine runs great. I still don't have it tuned (operating on old bolt on tune), but it holds idle and I can drive it in traffic just fine. It does not sputter or stutter anywhere and only very rarely will the idle fluctuate; it does not stall though.

Is this noise a concern? Could it be the Comp trunnions? I did not have this whirring noise with the pushrods that were too long, but obviously I did have the loud clacking. With the 7.400's it sounded like a solid lifter car (basically because it was), and with the 7.380's it had a little bit of clacking but no whirring noise, now with what I believe to be the properly measured 7.325's there is no ticking or clacking, but I have this weird noise. Keep in mind that with the AC on or the radio on I cannot hear it, but with everything off it just seems strange.

Could it be that I need to throw an extra 0.015-0.025 or so of preload on it? I'm already at 0.075, which I thought was the ideal preload on these lifters?

Any help is greatly appreciated!

Thanks,
Ed

ProfEd

iTrader: (1)

I forgot to mention that I am running Mobil1 10w30 synthetic oil. I know that is not the preferred oil anymore. If anyone thinks a different oil might shut these lifters up I will try that. For now though, I'm wondering if I should just try 7.350's and see what it sounds like; I'm just not sure about reaching out to 0.100" of preload...seems like a lot.

-Ed

leeluther252

iTrader: (17)

Just curious, were the heads milled? Depending on how much was milled and the fact that you are using a taller lifter it makes since that the pushrod would be shorter.

Preloads are usually in the .050-.080 range so I wouldn't go more.

ProfEd

iTrader: (1)

The heads are the standard 2.5 5.3 heads from TSP. I never measured them though, so it is possible that they mill them slightly. I am also running standard GM MLS headgaskets. I agree that 0.050-0.080 sounds right for preload, though I have read that some people prefer it on the higher end with the LS7 lifters, so that is what I went with. I wish I could capture the noise with my cellphone, but you can't hear it over the exhaust (which I am also re-doing next week).

Thanks again,
Ed