Max Safe Timing at cruising speeds?

[Dozerboy]

Well I wasn't happy with my mileage and upped my timing to a max of 11* at cruising speeds. I took a 2,000 mile trip and now it looks like I have a hurt HG. I had a little bit of pressure after sitting over night after the trip. It an LBZ with 5k miles on new Mahle HG, studs, and decked heads. I don't know it that was the cause or what. I ran 12* of timing for years and 100k miles before/while I blew my stock HGs. I had a discussion with people experience in tuning and pressure monitoring before upping it to 12* when I was stock. I was basically told crank it up until it starts to rattle and then back it off a little bit. I didn't have any rattle at 12*. Yes it was noisier of course. Just trying to see after a few more year's of lessons learned if that's just too much time to be running. I run very low boost at cruising generally around 2psi or less. Probably a little higher than stock fuel pressure.

 

[Chevy1925]

i doubt your tune ate your HG. not enough cylinder pressure at part throttle.

sure it aint just a cap or something else simple?

 

[2004LB7]

11* is not that much and at cruising, as James said, is not enough fuel to do any damage. The most I tried out I think was 13* and didn't notice any better mpg so I dropped it down a few to be safer

I bet it's more of a coincidence then anything else

 

[Dozerboy]

i doubt your tune ate your HG. not enough cylinder pressure at part throttle.

sure it aint just a cap or something else simple?

11* is not that much and at cruising, as James said, is not enough fuel to do any damage. The most I tried out I think was 13* and didn't notice any better mpg so I dropped it down a few to be safer

I bet it's more of a coincidence then anything else

Thanks. I just wanted to make sure I wasn't missing something.
Its probably a coincidence or something simple. There was some discussions in the boat thread that had me questioning my HG job. Like how studs are installed and an Acetone wipe down.
I believe Mark also mentioned oring heads at 700hp.
I also lost about 3 gal of coolant when I got a large leak durring a drive, but the truck never got hot.
The truth is that the only time I notice pressure was after that big trip and then the next drive after that there was a very tiny amount. However the truck doesn't get driven much. I haven't had an opportunity to really work it hard and see if I can duplicate the pressure, so I can fallow up on simple stuff.

I had half a mind to pull the top of the motor off and check the torque on the studs. Not because I'm concerned that I didn't torque them properly, but just because heat cycles or whatever. Not sure at this point if there is any benefit to doing it.

 

[2004LB7]

Thanks. I just wanted to make sure I wasn't missing something.
Its probably a coincidence or something simple. There was some discussions in the boat thread that had me questioning my HG job. Like how studs are installed and an Acetone wipe down.
I believe Mark also mentioned oring heads at 700hp.
I also lost about 3 gal of coolant when I got a large leak durring a drive, but the truck never got hot.
The truth is that the only time I notice pressure was after that big trip and then the next drive after that there was a very tiny amount. However the truck doesn't get driven much. I haven't had an opportunity to really work it hard and see if I can duplicate the pressure, so I can fallow up on simple stuff.

I had half a mind to pull the top of the motor off and check the torque on the studs. Not because I'm concerned that I didn't torque them properly, but just because heat cycles or whatever. Not sure at this point if there is any benefit to doing it.

I think retorquing the studs is really only important if they aren't being stretched like a typical head bolt would. I don't know what torque value equals equivalent stretch to the stock bolts or at least enough to maintain the clamping pressure after heat cycles. I think double checking them would be a good idea. But if you had a leak I don't know how much benefit you'd get from tightening them up more

 

[malibu795]

At what RPM And throttle load?
I've used as much as 15° pending RPM usually 2200-2550 while pulling grades
Generally 10-13° at 1900-2000
Current LMM is 8-10 at 1700-2000

 

[Dozerboy]

At what RPM And throttle load?
I've used as much as 15° pending RPM usually 2200-2550 while pulling grades
Generally 10-13° at 1900-2000
Current LMM is 8-10 at 1700-2000

2100 rpms and below
50mm3 and below
Above 50mm3 I run low timing to help lag