Engine/Transmission (1994 - 1998) Timing is everything

[Sandifer]

I have a '95 3500 5sp reg cab with a #10 plate and straight exhaust. I am thinking about having my timing set to 16degrees. Good idea? Will the EGT's be higher? How about mpg? It has 200k miles on it and never been checked. In the near future I plan on installing a 3k governer kit because I have 4:10 rear-end and right now my top speed is around 75. When I drive thru Houston I just about get runned off the road!!

 

[JGheen]

Well, first off the 3K governor spring kit is not going to help your top freeway cruising speed, lower gears will. The 3K kit will only make the injection pump defuel the engine around 2800+ rpm instead of the stock 2200 or so rpm. It just widens the power band up a bit.

It is always a good idea to bump the timing up and yes it will lower your EGTs some and also should increase your mileage as well. If the timing has never been checked, just refer to your engine ID plate on the side of the gear case, it will tell you your stock timing. Also, if the timing has never been checked or adjusted from factory setting, it is very unlikely the timing has slipped any. But if you do adjust it make sure you install a new lock washer on the timing gear. Some say the original one will be fine, but it's just cheap insurance to keep the timing in place.

 

[Jschafer]

Well, first off the 3K governor spring kit is not going to help your top freeway cruising speed, lower gears will.

If the Rpms increase it seems to me the Top speed would increase.

Higher RPMs Higher MPH? Or am I missing something.

 

[TPCDrafting]

I had my timing advanced to 16. 5 deg (Thanks R. ebel) and the only real differnces I see is 1. it idles much smoother and quieter. 2. it's harder starting when winter cold outside and smokes more when cold. 3. its quicker starting in the summer months. 4. no real mileage increase, but now I read in latest issue from Joe Donnely that mileage increases are more seen with bigger injectors like 370's. At least that's what I'm telling myself so I can start saving for a set. If there was an EGT drop it wasn't significant on mine. I didn't dyno before or after, but on the local test hill it was the same powerwise.

 

[sam616g]

I just had 4k governor springs installed and I can now cruise at a higher speed than with out the GSK. I also have 4. 10 gears and used to easily get to 75 mph (about 2200 rpm) and struggle to get to 80 mph (about 2400 rpm). Now I can fly up to 90 mph (about 2700 rpm) and have plenty of RPM to spare :--) .

 

[Bob4x4]

With 4. 10 and the gov kit you will be able to hit 100 mph easy Oo.



Mpg's



Enjoy it and don't sweat the small stuff.



Bob

 

[Lsfarm]

Timing and GSK

Sandifer, bumping the timing will give lower EGT's and probably better mileage. I would definitely add the 3GSK, it will allow a much higher freeway speed and close the rpm gaps in your 5-Speed's ratios. With a #10, 3GSK and bumped timing you will be very happy with the way your truck performs.



JGheen, if the engine starts defueling at 2200 rpm do you not think that the truck will be power and rpm limited ?? In what way would a wider power band not increase the top speed of a truck?? A stock 12v [depending on year] will often only free-rev to 25-2700 rpm, and not make enough power to pull the truck past 23-2400 rpm on the freeway. I've had trucks that free-rev only to 2550 rpm, and flat out, downhill do no more than 75mph [with 4. 10 gears].



12v trucks are speed limited by their governor springs and will enjoy a much higher max speed with a 3gsk or 4gsk installed.



Hope this helps Greg L

 

[JGheen]

Well, when my truck was stock I was able to get to 95 mph and the engine was reving upwards around 2900-3000 rpm. It may have not been fueling nor pushing the engine real hard but bone stock and my 3. 54 gears that was my top speed. After I installed the gov. spring kit, I still could not get much higher speed out of the truck nor rpms but I could feel the engine pushing harder up at the higher rpms due to the extra fuel up there. Just explaining from my experiences.

 

[I-6DZL]

There is a HUGE difference between 3:54's and 4:10's. I know from experience. I have 4:10's and as LsFarm has already said the 3gsk is almost a MUST HAVE! Before the install my truck would seem to labor to hold 75. Now after the install i have cruise (no labor at all) at 80 if i want to. When i start getting up to 82 to 85 then truck will again start to labor. I have not found my WOT top speed yet. I do not have a care in the world to find out what it is. My truck is for pulling anything i hook onto (reason for 4:10's). If i care to get tickets constantly then i'd switch in a heart beat to 3:54's.



As Greg also stated add a 10 plate and you will be all smiles!!!! I dyno'd my truck at 242 HP, 540 TQ with a stock trans, 10 plate, 3 gsk, straight exhaust, BHAF, boost elbow (40 lbs on dyno) I have not done my timing yet... . My max hp and tq both fell right around 2250 wich is where i cruise at 75 mph on the expressway. Could not be happier (except with a better trans)



Hope this helps

Curtis

 

[Sandifer]

Thanks for the info guys. I agree that I can't go wrong with a 3gsk or 4gsk. I am not looking for top speed hauling butt power but would enjoy having enough peddle to be able to pass someone who is doing 65mph and it not take me a mile and a half.

 

[JGheen]

I am very aware that there is a huge difference between 3. 54s and 4. 10s. I am just trying to say with 4. 10s and an engine that redlines @ 3000 rpm your not going to have a very high cruising speed no matter how much fuel you throw in at the top end. It has to stop somewhere and in Sandifer's case it seems to stop @ 65-70 mph. He should still be able to go all the way to 2900 or 3K on the freeway it will just take a little while until the 3 or 4K gsk is installed, then once more fuel is up there, it will reach max rpm and speed a lot quicker.

 

[1BadDad]

yeah..

Before Greg installed my 3k gsk , my truck was stock with a #6 tst.

Top speed was around 92-95mph. with my 3. 54's



After it was in and a slight pump adjustment, tops were 105-110mph

I guess it helped a little, but then again I cant drive 100 around town!

I love my gsk , it brought my ol' 95' 230. 000 at the time back to life and then some!

I think its a must have

 

[wtrenholm]

JGheen, it sounds like your truck ran better than ours (mine anyway) when stock or close to it. I haven't done the GSK or a plate yet but plan on it.



Having an automatic and 4. 10s our truck will just flat out quit making power about 2600 RPM or so, if your in 3rd it won't shift to 4th because your road speed is too low for the PCM, it just lays there, won't accelerate, won't shift, won't do crap, just sound like it's trying to lay a big turd. Once you lift off the throttle, let it shift, life gets good again. It may red line at 2900 but the only way mine is gonna see it is on vitamin "E".



Having a 1st gen, this 12V and a 24V; I would say the drivability of this truck is the least enjoyable of all of 'em. A big laboring pig actually, a hearty bump in pump timing kept me from having to go to therapy anyway.



There seems to be a lot of difference from one truck to another and it sounds like your's was good from the get go.



Wayne

 

[JGheen]

Yeah, I guess having an auto transmission would not help in seeing max speed without a GSK. My truck is the manual, so it came with the 215 pump, but I wouldn't say it ran better than others, it did get it petty good stock, but I was just stating my experience with the GSK/top speed and it is definately not something to take as gospel.

 

[Bob4x4]

Joe,The 215 trucks make their power to a higher rpm than all the other 12v's. The other trucks will never see 3k in odrive with the stock gov. The 3k's allow them to see 3k in o/drive,hence much higher top speed.



Bob

 

[JGheen]

Joe,The 215 trucks make their power to a higher rpm than all the other 12v's. The other trucks will never see 3k in odrive with the stock gov. The 3k's allow them to see 3k in o/drive,hence much higher top speed.



Bob

Well, there ya have it folks.

 

[Sandifer]

So after I get my timing done and I install my 3gsk,what is next? Injectors? Seems like I have come to the conclusion that larger injectors will allow me to get a little better mileage and power at the same time. Is this true? And does the pump have to be modified any?

 

[Joe G.]

Bigger injectors inject quicker so you have more fuel at a better crankshaft angle. The result is a little better mileage.



I don't have a 3k gsk. Maybe my '95 is a little different (CA model), but it would turn 2700 RPM when it was stock. That was about 98 MPH, but I was not watching the speedo very much when I did that. It was a rush on I 15 to Great Falls, MT on a Friday evening to get a trailer tire to the shop before it closed.



I have turned in the stock governor springs two clicks and turned in the high idle throttle stop a few turns. It will turn 3000 RPM now. I don't know if it will do it in OD or not because I don't want to go that fast. Over 100 MPH with my 3. 54 gears. It will hit 3000 RPM in lower gears.