Originally Posted by typ4

The torque cam was designed by the cam grinder I use, for the loggers when these trucks came out. They designed it for na and I used it in my turbo engine and it pulls , hard.
I sell them as they are a wholesale shop.

Originally Posted by dyoung14

could you give me more info on that cam you got? i might be interested in one:sly

Originally Posted by typ4

No because they wont give me more info, they developed it for the loggers in the late 80's

189 exchange plus shipping I do know that.

Originally Posted by typ4

The cam is 189.00 exchange plus shipping, So shipping both ways, to return the core is about 45 I would guess.

Originally Posted by ameristar1

We are all trying to crack the code on this engine, because most of the time you either say, "ok, I can live with the low power" or "that's it, I'm going to put another engine in this thing ( and it's usually a Cummins )." To the loyalist of IH, it's blasphemy, but at the same time there hasn't been a serious street combo that has held together and delivered the goods. And yes, it gets very expensive after a while. That's why we are looking for the cork in the bottle, and consensus is saying the cam. Russ' cam is the beginning, I am looking into more radical stuff, and that will depend on where pistons and valves meet. It's going to take a little time, but hopefully something will get made that will allow the engine to do 300hp without excessive amounts of boost.
Bigger pumps, injectors, turbos, ported heads, etc. can't do what they are meant to do when the cam timing won't allow it.

Originally Posted by ameristar1

The cam timing holds this engine back. The general consensus with most people that have commented so far about the 6.9/7.3 is that the heads can flow the air, the intake certainly has the volume, and it has the size. The injection pump can produce the fuel volume stock, and the injectors can be made to flow. But in the end, especially based on the numbers seen on the chassis dyno, there is a serious mismatch somewhere. And, like one poster said on another thread, most folks don't want to push these engines.

Even though more boost would be desireable, because of the cam timing the engine has a hard time processing it all. It's like the engine, as configured with the stock cam timing, is fighting itself, and the added boost makes a bad situation worse. So goodbye weakest link in the cylinder.

Freight Train asked me if I would sell a cam that would work with the stock bottom end, and I turned him on to Jones Cam Designs (704-489-2449) so he and anyone else who wanted something special can get it made. I talked to Mike yesterday and he can get a lot done with the stock cam core, as a regrind. Russ (typ4) has a torque grind that works really well.

Originally Posted by spencergt66

Well you just asked a whole mouth full. The camshaft is one of the most important parts of the engine it will make the engine make power in higher rpms or lower rpms depending on how its configured. On a conventional engine N/A usually the more lift and duration you have the better the engine preforms @ higher rpm but with a diesel engine, turbo charged that is, Usually the rpms are lower and the torque is made lower there for the time that the valves are held open during operation or travel of the piston is less cause the engine is being force fed air,turbo charging, instead of relying on vacuum.

Now this is where you need to pay attention to where your valves open and close. On a turbo charged engine before the end of the exhaust stroke both the intake and the exhaust valves should be open for a given amount of time, valve over lap, creating what they refer to as scavenging. This is when the charge air from the turbo is pushing out any remaining exhaust gases before starting the intake stroke usualy the intake valve stays open more than the entire downward travel of the piston (180 degrees of crank shaft rotation) say the intake opens @ 10 degrees BTDC exhaust stroke and stays open until 35 degrees after BDC intake stroke or 35 degrees into the compression stroke.
Right here is where what engine types differ.

Most conventional engines are still letting charge air into the cylinder during the upward stroke or compression stroke, like our engines IDI's, this cause more heat and cylinder pressure at TDCC Where as other engine types close the inlet valve before the intake stroke has ended thus letting the charge air expand in the cylinder. And when a volume of air that is already compressed, from the turbo, and is let re-expand quickly during the downward piston travel it becomes cooler decreasing the amount of cylinder pressure and heat in the combustion chamber. When this system is used it is necessary to have a larger quantity of charge air to make up for the air expansion in the cylinder Therein lies the problem and possibly some solution to the IH IDI turbo engines.

Because the 7.3 IDI inlet valve closes @ 42.8 degrees ABDC , from what i was told, the inlet air is crammed in there to the point where its probably being pushed back out of the cylinder due to the length of upward piston travel.

More then likely if the inlet valve was closed before the bottom of the intake stroke then you could have more charge air less emissions and a better balanced engine;Sweet


Hope that helps

Originally Posted by typ4

My cam grinder split patterns the cam and increases the intake lift to 261 lobe lift/392 valve
exhaust remains stock with 253 lobe 380 valve.

rocker ratio is 1.5 they calc it at .050 tappet lift.
the intake centerline is opened up to fill the cylinder longer.

Originally Posted by typ4

They developed it in the na days for the loggers, those trucks sold by the thousands in OR and WA. It really works good in my engine with the turbo. I can outpull my buddy and I have 355 gears and haul about 13k with the camper on and the buggy trailer.

Originally Posted by david85

Well crap! maybe a custom cam is in the works for me after all, Russ. Didn't realise the stock cam was a smogger retard like the ford big blocks. And here I was thinking these engines were untouched by emission devices. Turns out the enemy was from within all along.

Had no idea that the scavenging effect often described in the detroit 2 strokes borrows over to these 4 stroke engines.

Great breakdown of the theory there, spencer!!!!

Originally Posted by ameristar1

The things needed to design a cam properly for a 4 stroke engine are the same regardless of fuel type and injection system type. The OEMs do spend a lot of time doing what they do, but most of the time it still is a compromise, and lets be real; the people who count the money don't want the motor running too good. I've seen this happen over and over. The engineers come up with an excellent design, but can't get it produced. So instead, they are told to only go so far and not any further. When it comes to truck engines like the 6.9/7.3, they just put enough cam in there to make it run and not break.
With almost 30 years of advancements since this engine was produced, we can now have cam profiles that can wake these older engines up and make them live up to their potential. I would like to see an IDI hit 200-250hp before a turbo gets brought into the picture. I believe the heads, compression and fuel are already there to do that, but the cam has not been up to snuff, not by a long shot.

Originally Posted by ameristar1

According to Russ, the rocker ratio is 1.5 to 1, Gary gives the lobe lift at .253, so total lift at the valve is .380". I got a chance to see the ports on the heads, and like one other poster said, they are huge. This cam doesn't tap the full potential of airflow available with the stock heads and induction system.