Most of you fail to correct...
Thread Starter
TECH Enthusiast
iTrader: (4)
Joined: Mar 2009
Posts: 648
Likes: 1
From: Smithfield, UT
Most of you fail to correct... I've been reading on here about which cams will pass emissions and which won't. The consensus here is that you need 4 degrees of non overlap at 0.050". But most of you got here without living in the world of the old SBC. Had you been there, you would know you have to add 2 degrees effective duration at 50 for each .1:1 increase of rocker ratio above 1.5:1. So what you guys call a 220 cam, is really a 224 cam. You guys say a TR220-112 cam has 4 degrees of non-overlap at 50. But once you correct for your 1.7:1 rocker ratio, it really is a zero-overlap ( at 50 ) cam.
It just bugs me that none of you ever give any thought to this. Yes, it is more confusing. It's also part of why an LSx makes more power than the SBC for any given cam specs.
Now, before anyone jumps on me for this, just putting 1.7:1 rockers on the SBC won't add much. The LSx has a larger-dia. cam core. Thus a lobe that's IR for a SBC isn't IR for the LSx.
Give me a custom SBC block that takes SBC heads but LSx cams, let me fit it with AFR's best 180 heads, and let me compare that to a stone stock '97 LS1. Let me try several different sets of cam specs, and I'll get the SBC to cam-for-cam equal the LS1.
Okay, now we're way off the point of this thread. So, let the less-thoughtful of you go ahead and bash me rather than getting what I'm trying to point out.
It just bugs me that none of you ever give any thought to this. Yes, it is more confusing. It's also part of why an LSx makes more power than the SBC for any given cam specs.
Now, before anyone jumps on me for this, just putting 1.7:1 rockers on the SBC won't add much. The LSx has a larger-dia. cam core. Thus a lobe that's IR for a SBC isn't IR for the LSx.
Give me a custom SBC block that takes SBC heads but LSx cams, let me fit it with AFR's best 180 heads, and let me compare that to a stone stock '97 LS1. Let me try several different sets of cam specs, and I'll get the SBC to cam-for-cam equal the LS1.
Okay, now we're way off the point of this thread. So, let the less-thoughtful of you go ahead and bash me rather than getting what I'm trying to point out.
Last edited by Isolde; Dec 23, 2009 at 12:38 PM. Reason: typo
that's fine if you are using lobes designed for sbc's and 1.5 ratios.Alot of the new lobes are designed for the ls1 55mm cam and 1.7 rockers.So the actual durations is what is stated.
I've been reading on here about which cams will pass emissions and which won't. The consensus here is that you need 4 degrees of non overlap at 0.050". But most of you got here without living in the world of the old SBC. Had you been there, you would know you have to add 2 degrees effective duration at 50 for each .1:1 increase of rocker ratio above 1.5:1. So what you guys call a 220 cam, is really a 224 cam. You guys say a TR220-112 cam has 4 degrees of non-overlap at 50. But once you correct for your 1.7:1 rocker ratio, it really is a zero-overlap ( at 50 ) cam.
It just bugs me that none of you ever give any thought to this. Yes, it is more confusing. It's also part of why an LSx makes more power than the SBC for any given cam specs.
Now, before anyone jumps on me for this, just putting 1.7:1 rockers on the SBC won't add much. The LSx has a larger-dia. cam core. Thus a lobe that's IR for a SBC isn't IR for the LSx.
Give me a custom SBC block that takes SBC heads but LSx cams, let me fit it with AFR's best 180 heads, and let me compare that to a stone stock '97 LS1. Let me try several different sets of cam specs, and I'll get the SBC to cam-for-cam equal the LS1.
Okay, now we're way off the point of this thread. So, let the less-thoughtful of you go ahead and bash me rather than getting what I'm trying to point out.
It just bugs me that none of you ever give any thought to this. Yes, it is more confusing. It's also part of why an LSx makes more power than the SBC for any given cam specs.
Now, before anyone jumps on me for this, just putting 1.7:1 rockers on the SBC won't add much. The LSx has a larger-dia. cam core. Thus a lobe that's IR for a SBC isn't IR for the LSx.
Give me a custom SBC block that takes SBC heads but LSx cams, let me fit it with AFR's best 180 heads, and let me compare that to a stone stock '97 LS1. Let me try several different sets of cam specs, and I'll get the SBC to cam-for-cam equal the LS1.
Okay, now we're way off the point of this thread. So, let the less-thoughtful of you go ahead and bash me rather than getting what I'm trying to point out.
