TA_Freak

This isn't an LS1 ... it's a Pontiac 400 ...

I am degreeing an XE-268 and the cam card call's for 28° BTDC @ .006 of lift on the #1 intake lobe. I am ***** dead on with that ... but my ICL is coming out lower than I would have expected (100). The LSA is 110 whilst the ICL is 106 for 4 degrees advanced .. built in. I verified that I am indeed on true TDC with the degree wheel too.

Do I care about that ICL reading?

farmington

iTrader: (14)

Did you use a piston stop to set TDC on the degree wheel? This MUST be the first step in correctly degreeing a camshaft

TA_Freak

Of course. I mentioned that in my second to last statement.

The reading would indicate that the lobe is not symmetrical, which I know is why the ICL method isn't the best.

TA_Freak

OK ... it appears that the XE cam intake lobes are asymmetric and leaning in on the opening side. I think that would explain the weird ICL number. It's the only thing that makes sense since I'm dead ***** on 28 degrees at .006". .... and knowing that I'm on true TDC.

KCS

iTrader: (20)

Depends on how you are determining centerlines. If the lobes are asymmetrical, then you have to measure similar to how you measure to find TDC.

pantera_efi

iTrader: (1)

Hi TA, my guess is your heads are off AND your chosen Comp cam is the 224* 230* .477"/.480" C/L 110.

I would install THIS camshaft at 2* Advanced. (Split Overlap)

FIND TDC by measuring pistons #3 and #5 for EQUAL distance from the deck.
Now measure in the lifter bore area, the lifter position is higher on either cylinder #1 OR #6.
Knowing which cylinder is at overlap is important, to know when the Intake and Exhaust lifters SHOULD BE equal distant from the blocks deck surface.

Then adjust the timing chain crankshaft sprocket/timing chain cam sprocket for position to allow those two lifters to have the SAME LIFT.

This is Split Overlap, the best timing for this camshaft.

Lance

TA_Freak

Thats true ... Thanks.

Sounds like you know this camshaft. There seems to be a lot of hatred out there over this one.

The heads are still on. I've been running this cam for a while and suspected that it might be too far advanced and it was; it was at 6° advanced (camshaft). I should be able to get there by retarding the crank 4° which should put me at 24° at .006".

TA_Freak

Alright .. I'm done. There is a lesson that I learned. Check the duration first and don't assume anything. I learned a ton throughout the process. Here's the final numbers:

@ .050 IVO: 5° BTDC
@ .050 IVC: 141° BDC
Duration: 222°
ICL: 106°

@ .006 IVO: 25°
@ .006 IVC: 117° BDC
Duration: 262°
ICL: 106