Power seems less with timing advance

[rdodd]

After advancing timing from 10* to 14* btdc my truck seems more responsive but feels like is has less power and torque than before. Also the engine sounds quieter when standing to the side or behind the truck than it did before. Maybe its just my imagination but the power and noise seems more subdued than it used too. Has anyone else noticed conditions like this after a timing advance?

 

[nascar mark]

Hi, To take advantage you need the fuel and rpm's. Make sure your linkage,full throttle screw and diapham setting is at max.

Try uping the timing too 15 deg or so. Don't worry, your not going too hurt nothing as i have been running high timing for a long time to keep egt's lower.



Haven't noticed any boost drop with high timing but i reworked the pump for lots of fuel also. Did notice a drop off of bottom end but it pulls so nice right past 3100 and still pulling.

 

[rdodd]

My truck seems to accererate nicely at cruising speed when i hit the throttle but does;nt have the low end torque it used to have before advancing timing. Appartently advanced timing has a negative effect on low end power since you noticed it too. Maybe i should back off timing to 12* to gain a little more low end power and still have plenty on the cruising end?

 

[rdodd]

When the shop set my timing they reved it up to 2000 rpm,s to check true timing and as i was standing behind truck i noticed engine roared loud. After they advanced timing 4* and reved to 2000 rpm,s engine roar went more silent. Did yours get more quiet after advance?

 

[nascar mark]

Hi Rdodd,



I'm past that setting. Don't know were i'm at as i set my truck by seat of the pants tuning. I do know that advancing a little smooths out the truck,pulls nicer,sounds quieter. Advance it more and the truck is not as smooth, louder, but has more top end.

You might find a happy medium depending on your set up and transmission. The 91% tc in mine is tight so you loose some bottom end spool up but when it kicks in, in a second or two it takes off. Can't lay that 50' of posi any more. But has a very good mid & top end. Dyno'd at 271hp and 698. 1 ftlbs, so i'm doing something right. I believe if i was to retard timing a bit i would gain more ft/lbs but lose some hp. Not sure yet as i have only dyno'd 1 time so don't know for sure. Whats holding me back right now is my turbo. I'm at 39 psi on flat ground empty but thats about max for the stock turbo. Can't burn all the fuel i have now.

My work on the pump gives me lots of fuel, so the egt's go through the roof quick. 1500 deg is too easy. Have to drive by foot. The neat thing is my power screw is set lower then it was stock. [backed out from factory setting] so its easier on the pump.

Star wheel is counter clockwise as far as it can go. Yes, thats right. 1 or 2 more clicks and it would not be touching the side spring that holds it in place. Still have quick boost at any time.



mark

 

[rdodd]

I like the feel and smoothness of the advanced timing even if i lost a little low end punch. I understand that with advanced timing you get higher cylinder pressures, and i have concerns about head gasget and piston problems especially since i pull a 7500 # 5th wheel much of the time. How much can one advance timing before this could be a concern? I also run a lower stall torque converter --BD with new x-stator. I think it was an 89%. What idle speed do you run? I noticed with mine i have to keep idle speed down to about 700rpm or it wants to creep badly when in gear at a stop sign and goes in gear harshly from neutral if any higher.

 

[nascar mark]

As far as i know you are safe even at 17*. The 1st gens like lots of advance. It all depends on your fuel as every truck is different. I have personaly ran the advance as far as you can go for a long time with no problems.

I have my idle at 750 rpm's in drive. No problem with puting it it gear at that rpm.

 

[hdm48]

After setting my timing to 1. 6 it pulls better from the start and all the way up. Mine will rev to 3200 and with the transmission set to shift where I want it to it will push you in the seat hard when it shifts. I cannot floor it in the rain anywhere below 40mph or it will swap ends on you.

After putting in the lucas injectors I turned the power screw down and backed up the star wheel 3/4 turn and it still goes crazy when you punch it. The timing advance works well in mine.

And like all yours ,mine is quieter and becouse it has time to burn more of the fuel I'm putting in my EGT's are lower.

my 2c

--dave--

 

[TurboDog]

Someone have good instructions

My brother in law has a 1991 1 ton that he wants to make run better. Are there some good instructions out there for doing some of the things yall are talking about such as :advancing the timing, maxing out the throttle screw, power screw, and adjusting the star wheel? What other things can he do? His rig is stock now.

 

[nascar mark]

Hey TurboDog,



First things first! Have him buy and install a egt gauge before he turns any thing up or else he's going to have a melt down.

He also might want to buy a smaller exhaust housing for the turbo for a quicker spool up. Minimum 16cm.



Each truck is alittle different but he doesn't have to touch the power screw as it will shorten the pumps life. Do a search on 1st gen pump adjustments and timing the pump. The pump adjustment is as easy as loosening off the 3 - 13mm nuts on the pump & 1- 10 mm bolt at the back of pump,bottom right at pump & bracket. Bump pump upwards, towards top of engine 1/6" or 1/8" from scribe mark on front gear cover and pump base. Can be done without egt gauge.



Play with smoke screw[down makes more fuel at start up and takes turbo lag away off the line, but if down to far will make truck smoke at idle]

Diapham pin prick[most likely at 9 oclock] now needs to be turned to 12 oclock for more fuel delievery.

Star wheel [under diapham] turn down [clockways] for boost/fuel to come on faster. Have to play with this one.

Good luck. Remember egt gauge 1st. Need more help just ask, as lots of help from good people here.

mark

 

[Power Wagon]

I posted the 217HP dyno sheet, and here's what I did to get there.



1. Straightpipe exhaust. Still 3 inch, obviously still restrictive by the sound.



2. Power Wagon injectors.



3. Turned the governor stop screw several rounds to get more rpm. Probably added 250 rpm. Engine appears to go 2700 or so (no tach).



4. Turned the power screw up roughly two turns. It went just far enough to speed the idle back up to original speed before the PW injectors were installed.



5. Changed timing. I have not measured exactly, but I'm guessing it's in the 1. 5-1. 6 range.



6. 12CM hx35 turbo exhaust housing off a 2001 ISB. Wastgate set at 19-21 psi. Downpipe from same application.





Total cost? turbo housing was used, downpipe was used (stock downpipe from 2000 truck - muffler shop take-off), tailpipe over axle replaced, PW injectors new, about $600 total.



Truck is quieter than before I started (except exhaust noise), and achieves about the same economy. Smokes slightly, especially if cold, has a short dark puff if you suddenly mash it while cruising at 40-60. I made no changes to the diaphragm, it's stop screw, or star wheel under the diaphragm.

 

[TurboDog]

Thanks Nascar. Anyway you could send the diagram to my email. The first thing I told him was to get gauges. He is getting the bombing bug!