Attention: TDR Forum Junkies 
Ok guys, I've had a chance to run the governor spring for a bit now and here's what I've found...
First the spring really seems to override both the RPM AND Load governor functions/systems.
On a stock spring, you have both. The RPM will begin your defueling prior to your high idle limit setting. I think that defuel ususally is about 300 RPM (+-) lower than high idle. If the RPM warrants defueling BUT the LOAD requires equal or more fuel then defuel does not happen till later on. Either the RPM fully overrides the Load effect, or the Load itself decreases, resulting in defueling.
By using your high idle system you can run the RPM up to what you think is the safe max (usually around 3400 or so reliably, with stock springs). In doing so, you have basically drawn your "defuel" up to about 3000-3100 RPM, assuming load merrits the fueling to that point. It could be even lower if you cannot load the engine enough.
So, the spring pretty much overrides both. It will run pretty much "full fueling" right up to the governed speed. By that I mean the "physically governed speed", as in the high idle screw. If you have that backed out alot, then hang on when you go WOT with no load... . I flared OVER 3800 before I could lift off... shocked the heck outta me...
You will still have both RPM and Load impact your fueling, but it is significantly reduced.
I have found that the gov spring has literally dragged the max fueling point to pretty much were ever I've set the gov screw.
That results in a much stronger "feel" when doing even normal driving styles... .
I have seen more EGT's with it too... . normal around town has gone up by roughly 100*F across the board. I find it's a bit longer dropping to/below 300*F at shut down too.
I was on the freeway today coming back from BD. At 70 MPH, I would lift my foot and feel like I wanted to lean forward from deceleration... but when I just touched the throttle it was just as noticable if not more in terms of pulling me back. All in all, a very positive/aggressive response.
With my current settings, which I've been running about 1 week or so now, my throttle rod is all but turned right out of the "balls" it is mounted to on either end. My idle is 850 RPM in "P/N". Thats as low as I can get it.
Admittedly, my "full fuel screw" no longer has the lock collar, and it won't go in any further. It's pretty much right up tight... .
Around town, the EGT's are about 400-600*F with 600*F being a "peak" such as on start up from a light and pulling 1600 RPM or so.
It does come back down to about 450-500*F. This is also with a PDR HX35/14N/W. The HX 35 removed the 100*F temp increase form the spring change, plus another 50* or so.
It has also made major difference in my smoke levels. They are not any worse now than when I was running the 185's in the ole girl. .
When I did my dyno run at BD today, the runs were about 15 seconds long. At the very end of the runs I had peaked at ... 1700*F
... at that point I was already reading 284 HP. . I think I could have done that HP at less time, maybe 10 seconds or so... Keep in mind I was over 40 psi, but since my guage only goes to 35, all I can tell you is I was at the "S" in BOOST... 
which I estimate at 40-42 psi. I'm putting the 16cm back on since HX spools plenty fast anyway. .
The last item was unnexpected... . whether this was from the spring or spring + extra fueling, I'm not sure, but I was running outta fuel after two quick blasts to 3000 RPM smoking the rubber and release, and repeat, I ran outta fuel at the pump. The engine wanted to fart and miss, it ran like I had just changed nozzles and was starting it for the first time. After about 15 -20 seconds, the thing evened out, and you'd never have known it happened.
So, all in all, I like the spring. I like the responsiveness it has brought with it, and the extra boost it helps generate...
You can get good response with even modest pump settings since it holds the higher fuel levels longer.
Not bad for a cheap spring...
**edit** The last observation would be this, if you are wanting a fairly standard approach to raising your governed speed and still maintain the normal RPM/LOAD defueling process then just use the high idle screw. Nascar Mark has shown that it works in terms of bringing your top end RPM up.
If you want the method that requires more work/time and potentially more risk, then use the gov spring method. This restricts the rearward movement of the control collar which regulates the fueling. The control collar only needs to move slightly to begin the defueling process and the spring seems to delay that significantly. Lastly the items that may see excess wear and tear are the pump plunger which is going to be doing alot more work, along with the cam plate, return springs, and control collar.
If you go into it knowing that, you'll do so with the knowledge that it is a more "stones to the wall" approach. .
Remember, if it's not broke, you're not trying... .
Bob. .
First the spring really seems to override both the RPM AND Load governor functions/systems.
On a stock spring, you have both. The RPM will begin your defueling prior to your high idle limit setting. I think that defuel ususally is about 300 RPM (+-) lower than high idle. If the RPM warrants defueling BUT the LOAD requires equal or more fuel then defuel does not happen till later on. Either the RPM fully overrides the Load effect, or the Load itself decreases, resulting in defueling.
By using your high idle system you can run the RPM up to what you think is the safe max (usually around 3400 or so reliably, with stock springs). In doing so, you have basically drawn your "defuel" up to about 3000-3100 RPM, assuming load merrits the fueling to that point. It could be even lower if you cannot load the engine enough.
So, the spring pretty much overrides both. It will run pretty much "full fueling" right up to the governed speed. By that I mean the "physically governed speed", as in the high idle screw. If you have that backed out alot, then hang on when you go WOT with no load... . I flared OVER 3800 before I could lift off... shocked the heck outta me...
You will still have both RPM and Load impact your fueling, but it is significantly reduced.
I have found that the gov spring has literally dragged the max fueling point to pretty much were ever I've set the gov screw.
That results in a much stronger "feel" when doing even normal driving styles... .
I have seen more EGT's with it too... . normal around town has gone up by roughly 100*F across the board. I find it's a bit longer dropping to/below 300*F at shut down too.
I was on the freeway today coming back from BD. At 70 MPH, I would lift my foot and feel like I wanted to lean forward from deceleration... but when I just touched the throttle it was just as noticable if not more in terms of pulling me back. All in all, a very positive/aggressive response.
With my current settings, which I've been running about 1 week or so now, my throttle rod is all but turned right out of the "balls" it is mounted to on either end. My idle is 850 RPM in "P/N". Thats as low as I can get it.
Admittedly, my "full fuel screw" no longer has the lock collar, and it won't go in any further. It's pretty much right up tight... .
Around town, the EGT's are about 400-600*F with 600*F being a "peak" such as on start up from a light and pulling 1600 RPM or so.
It does come back down to about 450-500*F. This is also with a PDR HX35/14N/W. The HX 35 removed the 100*F temp increase form the spring change, plus another 50* or so.
It has also made major difference in my smoke levels. They are not any worse now than when I was running the 185's in the ole girl. .
When I did my dyno run at BD today, the runs were about 15 seconds long. At the very end of the runs I had peaked at ... 1700*F
... at that point I was already reading 284 HP. . I think I could have done that HP at less time, maybe 10 seconds or so... Keep in mind I was over 40 psi, but since my guage only goes to 35, all I can tell you is I was at the "S" in BOOST... which I estimate at 40-42 psi. I'm putting the 16cm back on since HX spools plenty fast anyway. . The last item was unnexpected... . whether this was from the spring or spring + extra fueling, I'm not sure, but I was running outta fuel after two quick blasts to 3000 RPM smoking the rubber and release, and repeat, I ran outta fuel at the pump. The engine wanted to fart and miss, it ran like I had just changed nozzles and was starting it for the first time. After about 15 -20 seconds, the thing evened out, and you'd never have known it happened.
So, all in all, I like the spring. I like the responsiveness it has brought with it, and the extra boost it helps generate...
You can get good response with even modest pump settings since it holds the higher fuel levels longer.
Not bad for a cheap spring...
**edit** The last observation would be this, if you are wanting a fairly standard approach to raising your governed speed and still maintain the normal RPM/LOAD defueling process then just use the high idle screw. Nascar Mark has shown that it works in terms of bringing your top end RPM up.
If you want the method that requires more work/time and potentially more risk, then use the gov spring method. This restricts the rearward movement of the control collar which regulates the fueling. The control collar only needs to move slightly to begin the defueling process and the spring seems to delay that significantly. Lastly the items that may see excess wear and tear are the pump plunger which is going to be doing alot more work, along with the cam plate, return springs, and control collar.
If you go into it knowing that, you'll do so with the knowledge that it is a more "stones to the wall" approach. .
Remember, if it's not broke, you're not trying... .
Bob. .
