cLAYH

Have seen that some people have replaced their gov. springs with higher rated ones and have read the excellent writeup on how to replace it, but.. why? What adavantage does it give? Is this something that everyone can benifit from or only those who are seriously bombed? I'm not interested in rasing my top end hoghway speed but have noticed the power drops off noticably after 70mph.

Is the replacment spring available at most Cummins shops or only from aftermarket? Thanx.

jughead

i was one of the first to do the gov spring. best mod of all i did. it is available from several sources. stock spring starts defueling before 2500. 3k spring willl start at about 3k to 3200 rpm. really wakes up even a stock truck. do a search on gov. spring you will find part#

Monty

Jughead is right, in fact I believe he was the first that I know of. I love mine. It just keeps fueling right up to 3200rpm. At almost 100mph I am burying the pyro and boost is at a steady 32-35psi. Needless to say..the fuel is there now in the upper end. Not bad for a 10 dollar spring.

You can pick the spring up from any Bosch authorized dealer.

wannadiesel

It's the cheapest HP you can make because
The faster you can spin an engine while still making good torque, the more HP you can make.

cLAYH

AHHHH that's why my truck falls on its face after 2500RPM. Guess I will make a trip to the Bosch dealer, thanks.

Monty

Make sure that you give them the part number that I have posted in the tech facts section. If you dont...odds are they wont know what to get.

darloa

Just got my spring in this week, just got to find the time to install, maybe today. Can't wait to see how much it helps, Darl.

frostie

You might try turning your High idle screw up first and modify your linkage to get full throttle after your adjustment. If you like what that does for you and want more than you can try the spring. I installed the spring and enjoy the extra power on the top end. I got mine shipped to me from Delco Diesel Services out of Oklahoma city. The Cummins people dont like selling those springs. They think if it didnt come in that pump than you should not put it in. If you go to cummins than just give them a part number and I would not mention what you are doing.
Just my 2 cents

cLAYH

Ok I think i will try that, is there any writeup on the high idle screw adjustment, did a search but didn't find much.

Do I screw it in or or out? How does it work, just delay when defueling starts? How far can I delay it until with just the screw? Any disadvantages or things I should be careful of? What is RPM flare?

Thanks again, I know its a lot of questions but its just so fun being able to increase power by playing with screws, its like havinga an old muscle car with an adjustable carb and timing. Don't get me wrong I do like the fuel injection on the modern vehicles but it does take some of the fun out of it.

wannadiesel

My last post in this thread explains exactly what you need to do with the high idle screw. It moves the max RPM and defuel points up a little, but not much. RPM flare is when the engine revs quicker than the governor can react, causing a momentary overspeeding of the engine. That's why you shouldn't mash the throttle in nuetral. You can also get flare in the lower gears on slippery or rough pavement.

cLAYH

Thanks for the info. I went ahead and backed it out two turns and adjusted teh linkage. N w I do see to get more fuel above 70MPH. Might just be me be seems to rev up a little easier as well. Unfortunatly I have an automatic and now it won't upsift to OD if the pedal is more than 90%. Have to back way off to get the upshift. Going to have to screw with the TPS again. Oh joy.