playing with timing

[andyr354]

Prety low tech for most here, but finally decided to try some different timing settings on my 93.

I already had the set of HF S wrenches in the toolbox for a while now so I put them to some more use. Was realy simple and only took 10-15 minutes to do. I advanced it right around 1/8" and tightened it back down.

It seems to have helped EGTs quite a bit. I will have to hook it upto the trailer and put 5K lbs behind it and see if it behaves better. With no load behind it I couldn't get my isspro pyro into the orange zone anymore though.

One thing I noticed. Seems to have a bit more power to me, but peak boost dropped around 3psi (right at 20 now). If the EGTs are more under control with the trailer behind it I will have to break that collar off the fuel screw and play some more. I am wondering if I need to back the smoke screw adjustment off some though so it doesn't fuel as much at lower rpms.

Andy

[wannadiesel]

Advancing the timing lowers boost, and it also reduces low end torque. What you are seeing is normal.

[Begle1]

From what I get, rotating the pump or jumping a tooth on the gear will increase base timing, and then there's still the mechanical advance on top of that controlled by case pressure/ RPM.

Wouldn't it be ideal to amplify the mechanical advance rather than add the base? (Of course, doing so would probably be infinitely more complex than the base advance...)

How accurate my thinking?

[gman07]

Adding to the "base" actually adds advance throughout the RPM range, and it's easy and quick to do. Ideally we would be able to leave the low RPM timing set fairly retarded for torque and exaggerate the dynamic advance function for more advance at the higher RPM's.

[Begle1]

The rate of advance with RPM stays the same, no matter what the pump timing is set at. Pump timing doesn't affect the rate of advance, only the base number that advances.

I think we're on the same page; I'm usually only good at talking technical to myself...

[gman07]

You're right, it doesn't change the rate of advance. It would be ideal for both HP and torque to be able to change that rate, but it's cheaper and easier just to rotate the pump.

Looking at a graph with degrees advance on the y axis and RPM on the x axis, rotating the pump is simply a vertical shift of the graph. Ideally we would be able to change the slope of the graph.

I'm usually only good at talking technical to myself...

Same here; it makes sense in my head, but it comes out in a confusing manner sometimes.

[g1625s]

Were you guys over on DTR a couple years ago when I opened a thread called 'timing is everything' ?It went on for several pages and Pastor Bob finally gave in (after some ruffled feathers, if I recall) and got talking about the timing piston inside the pump. That's where a fella could increase the dynamic timing for more HP on the top end without having to run like 20 degrees of base timing....

[Begle1]

And I take it that there hasn't been much progress on modifying the timing piston?

I've read through the Bosch pamphlet and figured out I'd stand a better chance of figuring out women then doing any sort of heart surgery on that thing.


I think finding an exotic, high-dollar fuel pump that can double case pressure across the entire throttle range would be more my speed. Instead of meeting vane pump pressure at the shut-down solenoid, increase the pressure by 50%? The pump required to do that would probably cost as much as a VP44, be equally reliable and blow every seal out of the VE the second you made it above 2000 RPM, though. You probably wouldn't even need the vane pump anymore...

What if you were to overdrive the vane pump? I take it the vane pump is gear driven; if you go to a gear that's half the size, would you get twice the pressure? Or would something a splode?

[dpuckett]

I'd think you'd be shooting yourself in the foot to change the gearing on the vane pump, but it might work.

I had considered a return spring for the advance piston that is a hair softer, or somehow installing a 2 step progressive spring that would hold the tension and keep the timing retarded at lower RPM, then gradually let it get full travel as RPM increased, up to about 4000RPM. ANy more than that, and I think you'd be asking for other problems. Of course, this would take LOTS of time on the stand, not to mention the time for R&D. I can leave that to the pros.

Daniel

[Flanra]

Do any of you guys know if there is a step by step guide with pictures on how to time the pump by using a dial indicator? I want to learn how to do it in the worst way. Or is there anyone thats willing and within a hour or two drive from pittsburgh that I could meet up with and could show me how its done... I just hate the fact that I have a truck and don't know how to properly time it...

[seeker1056]

I have the proper Dodge motor manual at home.

The details are quite good, but no real pix.

This is a from memory list - i may be off a little but u get the idea.

Find top dead centre n insert timing pin, then insert guage to pump, remove timing pin

Basically it is insert the guage into the back of the pump, roll the motor backwards till the guage stops working,then roll forward till the guage just moves. roll it back n forth a little to make sure guage is at neutral. set guage for zero, then roll motor to top dead again an insert pin, read guage.

If it is not in spec, at 1.4 mm lift, then loosen pump and rotate pump (motor pin in place) and rotate the pump till it reads 1.4 mm lift, and tighten pump.

Now if your wantin to increase timing, I am told you want 1.7 mm to equal that infamous 1/8" timing bump.

I dont know how much more you can go. What is 24 degrees? as some are runnin that much timing.

Any good motor manual should have this info on stock timing proceedure

[CAJUN 93]

dumb ??? time. i have a nice dial indicator in the shop. how do i attach it to the pump. is there a special adapter? i advanced my pump about 1/8 inch but sure would like to be more accurate.

thanks
daryl

[seeker1056]

nope, not something you adapt. It is a specialized indicator with a long probe o nthe end and it screws into the back of the pump in the middle of all the fuel lines.

Mine cost about $75 on Ebay.

However be careful some are in inches, not millimeters and if you get inches liek I did by accident, you will spend a lot of time with a calculator doin conversions

Isnt it fun not knowin the right questions to ask, before you get the answer.

[Greenleaf]

[quote="Begle1"]The rate of advance with RPM stays the same, no matter what the pump timing is set at. Pump timing doesn't affect the rate of advance, only the base number that advances.

You modify the amount of available timing by cutting the advance piston shorter. It can only move so far, modified or not. You want about 25°/27° of advance (full advanced position) when you reach 2400 rpm.

The piston moves over and hits the end cap. An OEM piston provides about 5 to 7° advance when at pull pump pressure.

Increasing pump pressure will not change this. Full advance will arrive sooner. You want a static time of 17° and have the advance come on steadily to 2400 rpm.

It's elementary really. Just think about how stuff operates.

[dpuckett]

ALso, I wouldnt rely to heavily on the timing pin for TDC. It's fine for adjusting valves, but for timing, I prefer to verify it by another known accurate method.

DP