IDIBRONCO
IDIBRONCO
You could also rev up the truck at a standstill and compare both gauges that way too.
. I suspect the difference is several more feet of line.
I have a hard time getting mine to drop. Just free reving it really doesn’t seem to do much. I want until she was loaded and working hard that it made a noticeable difference.Well, I hooked up the mechanical gauge the results of that tell me the electric gauge has problems. The mechanical reads 10psi with engine off and 9psi at idle. Revving the truck up, there was nothing I could do to drop below 6psi, and the needle was rock steady. So the pump seems fine pressure-wise. I guess I will send the gauge into Autometer to have it looked at.
The internal advance, which the hydraulic portion of the advance curve, keeps acting as long as engine rpms keep increasing. The mechanical advance done by the advance piston acted on by the light load advance arm works against the hydraulic advance by rotating the cam ring away from the rotation of the rotor. Ford set the 2000 rpm spec for timing just because its the middle of the rpm range, ultimately wide open throttle at hp peak is where timing is most critical for power, but with worn pumps and hard parts wearing differently, a pump that is set to 11* at 3000 rpms can make less timing down low than another rebuilt pump set at the same spec at 3000 rpms.You must be registered for see images attach
Absolutely, this topic could really use a thread in itself, it’s something I’ve wanted to know for a long time. I’m currently building a db4 for a customer and to get more data I’m machining some parts so we can actually watch transfer pressure in the cab with a regular gauge. Knowing transfer pressure we can calculate exactly how much timing we have, and with have a sensor output for transfer pressure I can use some electronics that will convert that number for us and show timing degree as a readout on another gauge.So once a person is more familiar with the curve can anything be learned by measuring and plotting the advance curve beyond the “ run it at 2000 rpm and set it at 9 degrees. That’s it you are done”
Or pistons?or kill fuel mileage.
That’s my best guess, don’t have the engine torn down so can’t say yet. Valvetrain all checked outOr pistons?
Oh well. You're not pushing the limits unless you break something once in a while.That’s my best guess, don’t have the engine torn down so can’t say yet. Valvetrain all checked out
That's about the same psi and general behavior I was seeing with a mechanical gauge, FYI. Pretty typical Facet behavior for those of us that have put a gauge on it.I finally got around to contacting Autometer over the weekend, and received a reply today. The customer service rep. gave me a list of voltages that the sender should be putting out for each psi from 1 through 15. Back-probing the wire harness at the back of the gauge, I found that (at least sitting in the driveway) the sender is putting out the proper voltage for the psi reading on the gauge. So, it appears the gauge and sender are working correctly, at least while revving the engine while sitting in the driveway. This doesn't explain the erratic 2-3 psi swings of the needle at times just cruising - unless there is an intermittent short or loss of continuity in the gauge wire harness. I have a new wire harness for the gauge, but I wasn't going to fish that through under the dash and through the firewall until I eliminated the gauge and sender as being at fault. Since the sender and gauge appear to be okay, I guess the next thing I will do is install the new gauge harness and see what that does. If we ignore the occasional erratic gauge reading for the moment, the gauge reads about 10 psi when the pump is turned on and before the engine is started. Upon engine start and idle, the gauge reads about 7-8 psi. Generally cruising will see a fuel pressure of 5-6 psi. Pulling a grade (truck empty but accelerating to increase speed) the gauge will read 3-4 psi. Putting the skinny pedal to the floor suddenly while pulling the grade will see the needle dip to 1psi or slightly below, but almost immediately recover to 3psi. Again, the truck never feels like it is running out of fuel, but that quick pressure drop when punching it is disconcerting. This could be function of "lag" in the electric gauge, or it could just be a case of the pump not keeping up with the sudden high fuel demand. The mechanical fuel pressure gauge would probably tell the tale for certain, so I need to figure out a way to rig that up on the cowl.