bumped timing does get better MPG's

[Todd T]

I picked up . 5 MPG on the last tank and i had towed my tractor about 20miles of that tank.



i bumped my timing to 17 degrees and this was the first tank through it since then.



I still need one good tank of just commuting miles to see for sure 1/2 a mile per gallon, knowing i towed is looking good though.

 

[Cooker]

Keep us posted on the long term. I am going to up mine shortly and am hoping for some sort of increase.

 

[patrobertson]

Just a warning. I have a 96 5 sp with 215's and #11 plate slid forward and I blew my head gasket!!! In fact heads still being checked out today. Its not a hard job but your truck is down for a few days to get the parts. My timing was at 17 degrees. The only mods is the plate, straight piped and the timing. I am blaming the timing. So now I am going to go 16 degrees.



Just food for thought. My max boost was 40 psi, but I don't think the gasket gave out purelly because of that.



Shane

 

[HoleshotHolset]

I think your gasket let loose after a lot of years (heat cycles) and mileage.....



17° is not really high enough to cause head gasket failure.....

Listen to an ISB... . they run a BOATLOAD more timing than the 12-valve crowd.



Put the thicker marine gasket on there and continue to run it like you have it... .



My $. 04 worth... .

Matt

 

[D. Showan]

I know this is nothing compared to you guys, but. When I raised mine from about 13 up to 14. 5 degrees my towing mpg went from about 11. 5 to 12. 5 Thats a big deal to me because it's about a 10% increase.

 

[HoleshotHolset]

There is a magic timing setting for every engine and every stage of fueling... . the only way to know for sure what your perfect setting would be is to test and tune.



Every engine is different but as a general rule they all like more than 12°... .



Matt

 

[Joseph Donnelly]

I gained about 2 mpg highway going from 13. 5 to 15. 5 deg. Head gasket failures, water jacket leaks to the outside, are fairly common around 1996 models. Cummins superceded the original head gasket with the marine version. Stock thickness is best for stock and moderately uprated engines, especially for starting in cold weather, 3283335. The 0. 020" thicker gasket, 3283339, is for engines over about 350 hp that are getting into a lot of cylinder pressure and boost (like 40 psi).

 

[fortunate1]

MPG up: I agree

My stock setting had slipped from 12. 5 deg. BTDC to 10. 5, according to the plunger measurement. Truck still ran well, but the fuel milage wasn't what it was at 60K to 120K miles. Keith (Rammin' On) set it to 15. 5 deg. BTDC, and I picked up 1 mpg around town. Haven't had a tankful-length trip yet, but I suspect that the highway fuel milage is up 1 or 2 also.



What causes mechanical breakdowns? Severe duty usage. Period. If you constantly run machinery at or near its limits, it will break sooner than if it were run in "normal duty" cycles. Bombing is cool for the extra power, but using all of it all of the time is going to accelerate wear and increase your repair frequency. :{

 

[Todd T]

to add to the story on an early morning run to Indy a few weeks ago, i clocked my odometer to be 1 mile short for every ten I traveled.



this was consistent for about 90 miles that it had my attention.

 

[Joseph Donnelly]

Todd, you need 10% fewer teeth on the speedo driven gear (if your truck has a 97-back system; 98-up is electronic). Likely you have the green 31 tooth gear. Get a 28 tooth 52067628 gear. You must have 35" tires. 255-85-16 tires take a 30 tooth (last 2 digits of part number) to make the speedo right, or 29 toth for best accuracy on the odometer.

 

[BCFAST]

My timing had slipped to about 10. 5 so when I had it fixed, we went up to 16. I HATE IT!!! The truck sounds like a PowerStroke, the mileage is no different, the temp is no different and I have NO bottom end!! All the timing did for my motor was kill anything below 1100rpm and make it annoyingly noisy. Im going to have it put back closer to stock... like around 14.

 

[illflem]

BCFAST, when you say your timing slipped down to 10. 5 it makes me wonder if it was really 12. 5 and is now 18. Not hard to do if it is not set exactly at TDC.

 

[PUMPERDUDE]

"Todd, you need 10% fewer teeth on the speedo driven gear (if your truck has a 97-back system; 98-up is electronic). Likely you have the green 31 tooth gear. Get a 28 tooth 52067628 gear. You must have 35" tires. 255-85-16 tires take a 30 tooth (last 2 digits of part number) to make the speedo right, or 29 toth for best accuracy on the odometer. " Joeseph Donnelly



Is there anything Joe D. does'nt Know?You da man Joe

 

[Don M]

I ask myself that all the time. Its just easier to listen in my case.

It took me a few months to figure out what the guy really knows.

I called one day and spoke to Jim A. and Jim said "I found it much easier to just hush and listen to Joe" He was right.





Don~

 

[R.ebel]

BCFAST, You and I have the same year trucks. I've got 370's and a 300 HP pump with my timing at 16 deg. (stock head gasket). I don't have any of the problems you are experiencing. 16 deg. works great for me