budhayes3

iTrader: (19)

I'm pretty sure that 4* is the most common, but I have seen 2* at times also.

blsnelling

iTrader: (4)

I don't see mention of it on either website. I'll probably call and talk to John tomorrow and see what he says.

budhayes3

iTrader: (19)

Yea, they don't mention it on their sites....if you can find out the ICL of the cam(s), then subtract that from the LSA, you'll get the advance...example:

110 ICL and 114 LSA = 4* advance

blsnelling

iTrader: (4)

After some digging, I think the TR220 has 4° ground into it. I'm going to call Comp Cams again tomorrow and ask the ICL just to verify. I'm hoping Patrick G will chime in here as well.

Patrick G

iTrader: (14)

Assuming a 65cc chamber size for 243 heads, your static compression on an LQ4 will rise from 9.5:1 (stock) to 10.22:1. If you want your power to peak around 6200 rpm, you will want to run the cam straight up with no advance. The dynamic compression would be 8.04:1 with no advance. Advancing the cam 4 degrees would drop your power peak to around 6000 rpm and your DCR would rise to 8.29:1. You'll make more peak power with 0 advance, but you'll 60' better with +4. Which one you ET better with depends on how high you're willing to turn your engine. For what it's worth, 4 degrees of advance helps the low and mid range more than it hurts the top end.

For a heavy truck without a lot of gear, you'll most likely ET better at +4.

Edit: I just noticed you have .035" milled heads. This would make your SCR rise to 10.96:1. DCR would be 8.60:1 at 0 advance. That's plenty high enough for pump gas. Run it straight up with no advance.

blsnelling

iTrader: (4)

The heads will have a 59cc chamber after a .035 mill. How does this change the CRs above? Gears are 4:30, but tires are 33x12.50s. I would prefer to set shift points at 6000, but am willing to go to 6200.

BTW Patrick, thanks for weighing in on this!

blsnelling

iTrader: (4)

Thanks for the update Patrick. It's really interesting to see how much valve events affect the DCR. I'm going to have to stufy up to see how that works, what it really means. Interesting how more compression can allow you to run a little more cam affectively.

I do believe that I've read that over 9.0 DCR and you start getting into trouble on pump gas. Is that correct. What kind of DCR would I be at if I went +4?

Dezert1500

iTrader: (11)

I'm no expert, but here's my take...Correct me if I'm wrong

-59cc you'll be around 10.8:1 and 8.5:1 DCR

I believe on 91 octane try and stay below 8.5:1 DCR with 93 you can go a tad higher but beware you may face detonation without pulling timing. It's better to keep the timing with a lower DCR.

Are you sure their is no advanced ground into the cam? Most street cams have advance ground in to help the low-midrange.

Advancing the came raises the DCR because you are closing the intake valve sooner with the piston further down in the cylinder. This is what brings the torque peak down in the rpm band.

Why not shift at 6500rpm? Your cam with that duration should pull to 6500 especially if not advanced.

blsnelling

iTrader: (4)

It's a custom ground cam. I'm going to call again today and ask what the ICL is, just to verify.

I figured that was what was happening, but wasn't sure. Thanks for clearing that up. In other words, the piston has x° more stroke to make compression when the cam is advanced and the valves are closed earlier.

Admittedly, I'm being very cautious on my rev limit. Yes, I want this motor that makes all this power. But I don't want to break it, or wear it out either. I'm also trying to stretch the life of my 4L60E. In my mind, the difference between shifting at 6,000 and 6,400 could be rather significant in the life of the engine and tranny. No?

blsnelling

iTrader: (4)

Now I'm really going to stir the hornet's nest, lol. What break-in oil should I run? I will be assembling the crank with Clevite assembly lube, and will be using Comp Cams lube on the cam. I plan to change the oil early and often. I'm a Castrol, Penzoil, and Rotella fan. I do know to not use synthetic until after the engine is broken in. I also don't want to have to source some exotic break-in oil. I would like to be able to use something found locally on the shelf.