anyone ever swapped JUST a cam?

[fatty]

Has anyone ever done a cam swap where the only thing changed was the cam? I recently swapped to a Hamilton 188/220 and went from stock HG to a .020 over HG and am very displeased with the results.

I went for a drive today and got on it a few times and then my turbo oil feed line started leaking everywhere so I had to stop. My pyro was literally moving as fast as my tach, in 3-4 seconds it went from 600 to 1700 degrees and showed no signs of slowing when I let off. I don't recall seeing over 1600 with stock cam. Boost was 46-47 psi stock cam, now today I saw 45-46.

Also I don't think it spools any better than the stock cam did, but it's kind of hard to say since my pickup was down for 2 months. It definitely doesn't spool much faster if it all though.

Is it possible to install a cam wrong and cause anything like this?

[fatty]

This is with SDX 5*18 and a 63/68/.83 t4. All the usual pump work, airdog, built auto.

[BC847]

Have you toyed with the timing since the new cam?

[fatty]

A little. I jumped a tooth while I had it apart so I pulled the pump back to where I think it's the same timing as where I had it before.

[BC847]

Taking stabs at stuff . . . .

I wonder how much the change from stock, to .020" over head-gasket changed things. I run a .010" over with that cam (as recommended by Zach).
- Have you verified the valve lash since the cam swap (after perhaps 25 ~ 50 miles break-in).
- Are you running stock/OEM valve lash?

- Do you have a fuel pressure gauge, and if so, are you seeing a small dip in pressure at Full throttle @ higher engine RPM? It's my experience that when this happens, there's also a notable drop in IP case-pressure with the resulting RETARDING of the dynamic injection event timing. > Doing a WOT pull from stop to 55mph , with the engine wound-up under this load, back off the throttle just a shade and see if you can feel a little more pull. This retarding of timing is gonna put more heat in the exhaust thus higher EGTs.

- When was the last time you pulled the rocker-arms and inspected the bottom of the rocker-arm shafts? I've found a couple of mine galled and as such, they presented with variable valve-lash."

[Remps]

I noticed my 96 felt a little lazier with a 20 over gasket, ended up going back to a standard gasket the last time I had it apart. Do you need the 20 over for cam clearance?

[fatty]

I needed the .020 over for clearance and I set the valves at .009 intake and .019 exhaust. I did a couple retorques on the studs and I had set the valves within ten miles of my test runs. I don't think fuel psi drops from 22-24 psi but I'd have to verify that one I get my oil line fixed.

I have about 250-300 miles on the cam now, if it was coming apart from bad install would I have noticed it by now in the oil? I just changed the oil when I did my final torque and reset the valve lash and didn't have any metal on the plug.

[RCCUMMINS89]

Correct me if I'm wrong, but didn't you have outrageous temps with those injectors with the old cam too?

[fatty]

Not real bad, think it would hit about 1600 or so max. Now I could have easily pegged the 2k pyro but I let out. It certainly didn't get hot this fast, the pyro never even slowed until I eased up.

[RCCUMMINS89]

Boost is the same, timing should be..... I'm wondering if it is in fact the 20 over gasket. I know a local guy rebuilt his engine and used a 20 over.... best way to put it... it runs like sthi. It gets CRAZY hot, for his setup.


Again, this is me wondering, and thinking out loud. I don't know where else to look right now.

[Remps]

How much piston to valve clearance do you have? Could you get the valves sunk and run a standard gasket, or has the head been decked too much? Is it installed at the standard 99 degree centreline?

[fatty]

I ended up with .003 extra clearance with the .020 HG. I don't remember the exact numbers, but I had more than stock piston protrusion for some reason and less on the valves.

I just don't see how .020 could totally negate the benefits of a cam, much less make it run worse.

I didn't degree the cam when I installed it.

[RCCUMMINS89]

And I'm not saying it is......Just thinking out loud. I've never seen a scenario where someone put in a cam, and ran hotter.