Another PY'er had asked about the cam I am currently running - GM# 12664572. It was touted as a non-DOD LT1 cam, 200/207° @116.5.
Greaseball noted to me to check this cam out again. I was horrified to discover somebody at GM goofed, the real spec's are 189/223° at 120° separation!
I emailed the vendor, Michigan Motorsports, about this issue. This was their reply:
Good morning,
Back when you purchased that camshaft, everybody (including ourselves and several large GM parts retailers) who was selling that LT5 camshaft had it listed as being similar specs to the L86/LT1 camshaft, as that is what the information everybody had at the time showed the specs as being. I'm not sure if GM changed the camshaft now that the LT5 is just a crate engine rather than a production car engine, or if the information everybody had was wrong all along, but it was later discovered when one of the larger companies selling that camshaft measured it on one of their Andrews camshaft machines that the specs were quite a bit different than thought and we all updated our listings to show the 188/223 specs that they informed us of.
At that time we went ahead and stopped selling that camshaft since it wouldn't be a good fit for most of our truck/SUV customers even though we hadn't heard any complaints from anybody about how it ran in those engines at all.
We now sell the Texas Speed camshaft in the link below for the L86/LT1/LT4 DOD deletes. To use that camshaft on an L84, you would need to upgrade to LT1 style valve springs as well.
If you don't want to run the LT5 camshaft, you can return it to the address below for a refund or store credit.
The LeMans has of course been running for the last 6 months with this wrong cam. Other than the wide separation, it seems to be a Gen V version of Comp's Thumper.
Yuck.
So I will replace it and now am leaning towards the L8T cam, which is the same as the 5.3 (193/199°) but with DOD delete. The L8T is a 3/4 and 1 ton truck version of the Gen V but in 6.6 liter. The smaller 189° does indeed move the LeMans briskly and with less exhaust duration should get better power and mileage.