Advanced CAM timing to Save Fuel?

[gto78]

I recently changed the timing chains in my 98 ford explorer which is the 4.0 SOHC engine. It's not the ford engine, this is the engine ford contracted to buy from a company in Germany, and then slapped the ford logo on the plastic engine cover.

While I was re-timing the cams I decided to advance both cams 2 degrees. What a huge difference in performance it gave me. As expected it lowered the rpm band a little bit, but it has more torque than before, which results in less pressure on the accelerator to get moving.

My main question is whether that is helping or hurting the gas mileage?

 

[tom slick]

how did you advance them 2 degrees?

 

[dwendt44]

IF it lowered the RPM band, it should help mileage.

Many newer engines have their power curve high to get great numbers for the catalog and advertisment purposes. This can hurt fuel mileage.
If you need to keep revs up for decent power, it's using fuel.
If the motor is loafing, it's not using as much fuel.

 

[NYSteve]

Probably found better timing than before that lead to more efficiency of the engine. Better efficiency = more power = less gas used

 

[gto78]

With this engine you can't just line up a couple timing marks on the gears like the good old days, you have to buy a 500$ tool made just for this specific engine....in my case I borrowed it. The tool kit has several big clunky parts. Basically there are two special cam holders that lock onto each camshaft and hold each into the correct timing position. There's also another piece that clamps onto the harmonic balancer. Once everything is in proper alignment, you tighten the gears on the end of the cams in place.

The trick is that your supposed to line the timing mark on the balancer at zero first before clamping everything in place... BUT you can physically turn the harmonic balancer (crankshaft...) as many degrees as you dare- and then clamp it in place as though its at zero. I don't really know if it's true or not, but I've been reassured that this engine is not an interference engine. So I wasn't worried about a valve hitting the piston.

After doing this change I noticed a huge difference in throttle response, braking power due to more vacuum, and a much smoother idle. It's a 4500 lb vehicle with oversized tires and has no problems doing a burnout. Before advancing the timing it had very little torque and couldn't do that.

 

[punisher]

Ford retarded cam timing in just about everything. Cams were retarded to cut down NOX emissions, engine performance be dam*ed. On older timing sets (factory) the gears have a 4-6 degree retard built in.