General Cam Degreeing Question
Thread Starter
TECH Fanatic
Joined: Nov 2011
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From: Woodstock, GA
General Cam Degreeing Question 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?
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?
Thread Starter
TECH Fanatic
Joined: Nov 2011
Posts: 1,367
Likes: 144
From: Woodstock, GA
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.
Split Overlap Cam Timing 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
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
Thread Starter
TECH Fanatic
Joined: Nov 2011
Posts: 1,367
Likes: 144
From: Woodstock, GA
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
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
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".
Last edited by TA_Freak; Oct 27, 2017 at 12:40 PM.
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Thread Starter
TECH Fanatic
Joined: Nov 2011
Posts: 1,367
Likes: 144
From: Woodstock, GA
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
@ .050 IVO: 5° BTDC
@ .050 IVC: 141° BDC
Duration: 222°
ICL: 106°
@ .006 IVO: 25°
@ .006 IVC: 117° BDC
Duration: 262°
ICL: 106
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