by Turbo67 » Sun Aug 02, 2015 8:19 pm
I would appreciate those of you experienced with the VE Pump to give this some thought and recommendations.
I’ve been trying some mods on my 93 Cummins with a VE pump. Bought the Truck about a month ago.
It’s a 2500 5 speed, extended cab, long bed.
When I bought this truck the power band was 1700 to 2100 rpm. I could get it to go to 2500, but not really any power after 2100. It ran fine, got around 24 mpg on a 250 mile trip at 65 mph with the AC blowing cold, just very narrow power band.
Installed a fuel pressure gauge after the fuel filter and an intake manifold pressure gage to monitor things.
I saw a max of 16 psi of boost in 4th gear WOT.
Truck makes 5 psi of fuel pressure back then and now after all the below changes.
Indexed the throttle shaft one notch, This was the single most eventful thing done. Truck will now make 21 psi boost in 4th gear, pull to 2800 rpm and rev on up to 3000 rpm. Much more driveable with the extended rpm range.
Next tried indexing the aneroid fuel pin to the richest setting, maybe a little more power, hard to tell. No smoke at all.
Moved the star wheel under the aneroid down to its lowest setting, no difference in power. It was within 3/4 turns of bottoming out when I removed the top and is now fully bottomed. No change in power.
Next turned main fuel screw in 1 turn. This raised the idle speed, and I had to lengthen the control rod by 3 turns to back down the idle speed. No change in power. Maybe a little smoke at lower rpms and WOT.
Turned the main fuel screw in ½ turn more (this produced a slow return to idle speed) so I backed it off ¼ turn. This does now produce some smoke at low rpm and WOT. Hard to say if it makes any more power, but maybe slightly more. It does now smoke when rolling into the throttle from slow speeds in 2nd or 3rd.
Next adjusted the high speed throttle stop screw and moved the linkage pin to the inside hole and the return springs to the outside hole to get more travel out of the throttle. This made a noticeable difference in power, boost and smoke. It will now achieve 23 psi in 4th gear at WOT. Smokes rolling into the throttle from slow speeds in 2nd or 3rd.
(I got more out of the 2 throttle indexing / throttle travel changes than any other thing I have done so far)
Started backing off the aneroid set screw to try to reduce the roll into the throttle smoke. ¼ turn increments at a time, at 2-1/4 turns leaner, it made a little more power. But ½ turn more leaner the power dropped. So I turned it back down ½ turn, power did not return. Cannot seem to find this lost power. I tried more turns in each direction, but don’t seem to feel it anymore. It does still smoke when rolling into the throttle at low rpm.
Checked the timing, at TDC, I have .046 inches plunger lift, this is very close to the correct setting of 1.25 MM, (.049).
Installed the 4200 rpm governor spring and clipped two coils from it. Clipped, it is essentially the same static length as the stock spring.
No change at all in power level. I have not, don’t plan to rev it over 3000 rpm, (stock valve springs) but it hits peak torque still around 2500/2800, so no reason to anyway. It is more responsive to small throttle inputs, but does not make any more torque than the stock spring.
Changed the fuel filter, same 5 psi fuel pressure downstream of the filter, at idle or WOT as with the old filter.
Tried it with the KSB connected and disconnected. I cannot tell any difference. I did bench test the solenoid on the KSB, when 12 volts is applied, the solenoid does move the plunger out to close the hydraulic circuit. I have read that depending on the year of the engine, when power is applied to this valve the results can be opposite.
Roll into the throttle in 2nd or 3rd gear does not break loose the tires. They are dried out old radials.
Don’t get me wrong here, the truck runs night and day better than the day I drove it home last month. But I was expecting lots more torque with these tweaks.
***What am I missing?***
I really expected a roll into the throttle to break loose the tires….am I expecting too much?
What else can I try to boost torque for no cash outlay?
Is it time to consider spending small amounts of money for the next attempts at increasing torque?
Turbo67
93 Cummins 5.9L, VE Pump, 300,000 miles
4200 RPM Spring, indexed stock fuel pin, Fuel Screw maxed, then replaced with longer "Hot Screw", aneroid screw tweaked