Cam Timing Idiot Check

buzzword

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Check, I’m an idiot!

Just installed 750 kit, Shell #1 regrind, etc.

Did all the prework to degree the cam after installation. Adjusted cam chain tensioner correctly, set up zero lash on all 4 valves, etc. After checking this 3 times with the dial plunger 3 different places on the valve spring keeper, and my numbers didn’t change at all. Checked all valve events @ 0.050” on everything, and this is what I came up with:

R - IO 15* BT / IC 51* AB
R - EO 37* BB / EC 25* AT
L - IO 16* BT / IC 51* AB
L - EO 37* BB / EC 25* AT

Seems off - calcs out at 246/242 I/E duration, and intake centerline of 108* / exhaust centerline of 96*with 40* of overlap, which puts the overall lobe centerline @ 102* - I think that’s OK, but I’m starting to drive myself crazy here. Based on the search function here and elsewhere, these numbers for a Shell #1 should be 25/45/45/25. So, what gives? What’s the fix? I can’t play 4 dimensional chess this way, but I’m also guessing this is a simple fix overall, or maybe it’s fine?

If I do need to press and re-set the cam gear, or move it one tooth, what direction and how far?

Would appreciate any input or sage wisdom here. I’ve searched exhaustively on this and other forums and can’t find the dumbed down walter-proof idiot version. Maybe this is happening because it’s 12:21 AM and my kids drove me bananas all day, but I can’t wrap my head around this crap.
 

grizld1

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Buzz, the EC is correct, and there's no adjustment that will change the EO (8* error), IO (10* error), and IC (6*error) without changing the EC. If those readings are correct, you have a badly misground cam, and you're not an idiot. On my Shell #1 (bought years ago from Shell) I wound up timing the IO at around 20* and the other events fell where they should, and as Gary Hoos has noted, this is common and seems to do no harm. But your grind is a different thing entirely, and you might want to talk to your vendor about a replacement.
 

buzzword

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Idiot confirmed. Was off by one tooth. What's worse, I thought I could get away with using a slightly used cam chain.

Nope!

New chain installed, re-checked everything, and here's where it landed:

R - IO 23* BT / IC 42* AB
R - EO 45* BB / EC 20* AT
L - IO 25* BT / IC 40* AB
L - EO 45* BB / EC 20* AT​

Spoke with @hooser who confirmed this is within spec for his regrinds, and after reading here there + everywhere it would seem that focusing on the exhaust events and letting the intake fall where it may is preferred - right @grizld1? I'm going to call this close enough - though the intake lift seems to fall a bit short on the intake side with 0.393" vs an advertised 0.410" -- probably doesn't matter that much as I'll likely never have this thing sideways at the ragged edge.
 

kiwi

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I had something similar when I installed my Shell cam many years ago, numbers were way off. A phone call to Shell didn't help, he says just run it, and Grizld1 pretty much told me not to worry as well. I took it to a local cam grind expert, verified my numbers were close, he told me to run it too. So I did, and still am. I think when Hoos took over Shells stock he found a few misground cams. I think I got one of those. Your numbers seem closer to #1 events, so just run it.
 

grizld1

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Yep, I'd run it. The main thing to avoid is advancing the EO unless you want to be doing a lot of short shifting, and you're looking good there. You might retard things two or three degrees later if you decide you want more kick at higher rpm, but the setting you have might be just what you want.
 
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