Timing on 1st gen engine

[noseamum]

Wondered If someone could give me som tips on how much timing I need on my cummins, it is a 1990 that didn`t come with a IC standard.(has higher compression than the later?)
I`ve added a second gen intercooler and modified the pump so it revs 3600rpm and have boost cooler injection fitted.It has 37psi of boost with a hx35 but only has 234RWHP with 35" tires and 3.07axles behind the 727.
Was hoping some proper timing would help raise that number.

 

[Grey Wolf]

The proper way to time a VE pump is with a dial gauge that fits in the end of the pump. About 15 degrees is a good start. Some people loosen the pump hold down screws and more the pump towards the block for a "back yard" timing advance but I prefer the dial gauge method.

 

[crashnzuk]

I bet your low hp to the ground problem is that 727. Unless you have a good converter, you aren't putting all of your power to the ground. I have ridden in a couple of non i/c trucks with a 727 and it seemed like LOTS of waste between the crank and the ground. Those stock converters are just not up to the demands of a hopped up 12 valve.
Travis..

 

[ameristar1]

I bet your low hp to the ground problem is that 727. Unless you have a good converter, you aren't putting all of your power to the ground. I have ridden in a couple of non i/c trucks with a 727 and it seemed like LOTS of waste between the crank and the ground. Those stock converters are just not up to the demands of a hopped up 12 valve.
Travis..

You are absolutely right. The 727 is sucking 40hp out of the game. A stock Cummins with the auto only puts 120hp to the ground. As the torque is increased the stall speed is going up, which for this motor is all wrong. Make a call and get a proper convertor for your combo. Since you ran it on the chassis dyno, use those numbers as a reference. Combine that with the timing adjustments and it'll really wake the truck up.
The compression ratio, IIRC, is 17 to 1 on the nonintercooled versus 16 or 16.5 to 1 for the intercooled version.
Just out of curiosity, how are your egt's at that boost level with the HX35?

 

[noseamum]

The EGT`s will go up to approx 1430 degrees up hills, running with 50/50 water/isopropanol injection.
The pump is "timed" 1/8".

 

[Exekiel69]

Build that tranny a little better if You haven't already, looks like that is the problem.

 

[rebel_horseman]

Another potential limiter is the highway mileage friendly 3.07 gears. If you tow anything you're going to put strain on the trannie. I'd highly recommend a trannie temp gauge if you don't already have one installed. The 3.07s will give you great mileage and be OK with the Torqueflite, but swapping gears will net you a bit better performance.

But I will agree with everyone that your main problem is probably the sucky converter in there now. According to your numbers, the engine is pushing enough fuel and making good power, it's just getting lost in the drive train. Your trannie clutches may also be slipping which will result in a loss of power to the rear axle.

 

[rebel_horseman]

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[TexasGunmetal]

You should be able to help those numbers by flushing the transmission and refilling it with Type F fluid. Type F has much better frictional properties than Dexcrap III. Slippage wears out the clutch pack prematurely. Dexron fluid encourages slippage instead of "grippage" when under load, while type F works more effectively by allowing the clutch pack to positively engage under heavy load instead of slipping.

Synthetic type F will protect 3-5x better than regular type F and operating temp will be considerably lower also.
Some options:
Amsoil Super Shift
Royal Purple Racing ATF (best deal on RP)
Redline Racing ATF

Royal Purple and Redline are both good., but Amsoil is the most affordable and their lubes always perform great. Under $6.80 a quart with preferred membership vs 10 bucks a quart for the others.