Cam question

[spencergt66]

Just wondering if anyone has the oe cams specs. By that I mean degrees BBDC/BTDC of valves opening/closing and duration. Thinking with a better cam setup more boost would be achievable without shaving pistons and what not but not sure on the stock setup

 

[david85]

Typ4 has some "torque" cams that seem to be working well. Other then that, it seems custom cams are just not available for these engines.

Sorry I can't help woth your main question though. Have no idea but am curious.

 

[icanfixall]

This is what my International Navistar shop manual says about the cam..
valve timing
(top of ramp)
intake open 17.2 degrees BTDC
closes 42.8 degrees ABDC
exhaust open 51.2 degrees BBDC
closes 20.8 degrees ATDC

 

[ameristar1]

Along the same line, what is the rocker arm ratio, and you did say that the lobe lift was something like .253", right?

 

[icanfixall]

The lift is intake 0.2535
exhaust 0.25308
I really don't think the exhaust lift is measured down to 10o thousands of an inch like they list it.

 

[ameristar1]

They don't take it out that far. .253" intake/.253" exhaust. My cam guy said that he can regrind the stocker to do whatever I want. May require longer pushrods, but it can be done.

 

[towcat]

before you get all crazy on the lift, you might want to check out the coil stack height on the valvesprings.

 

[ameristar1]

before you get all crazy on the lift, you might want to check out the coil stack height on the valvesprings.

The springs and cam have to go together, seeing as how the motor has soft springs from the factory to make it last a long time.

 

[spencergt66]

wow no wonder you cant pour the boost to these engines with numbers like that. Im not so much worried about the lift or duration more or less the inlet valve closure way way way too late for a turbo diesel engine I'm sure its fine for the N/A engines though

 

[ameristar1]

Just wondering if anyone has the oe cams specs. By that I mean degrees BBDC/BTDC of valves opening/closing and duration. Thinking with a better cam setup more boost would be achievable without shaving pistons and what not but not sure on the stock setup

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.

For a street motor possibility, working with existing set ups, I would propose the following:

Slightly larger turbo that can flow enough air for 350-375hp that can bolt up to the pipes of the Hypermax, ATS, Banks system.

Custom street performance cam that will run strong from idle to 3800 rpms or so. The cam will redline at 4300 rpms, but with the hp peak is at 3800-3900 rpms, there would be no need to rev it past the stock governed rpm of the pump. With the extra rpm available, and the extra airflow because of the engine speed, extra boost wouldn't necessarily be needed. And it will fall within the structural limits (rpm wise) of the stock internals.

Injectors that can match the hp goal.

Mike's cams don't lay down hard after the power peak, as ground, unless the customer wants that to happen, and they offer the broadest powerband within the rpm range the customer chooses. No weird harmonics either.

 

[spencergt66]

well thats good to know that there is someone out there willing grind a cam for you just kind of wondering what there cost would be on something like that? I'm kinda of thinking of looking for a good core motor to build up as a swing engine but want to get a little better over all performance out of the engine not like building a race engine or anything. Just looking for something that would produce a better torque curve I think that could be easily obtainable by simply changing the inlet valve timing looking at the stock numbers its fairly evident as to where the engine is working against itself but not 100% sure if I'm going to go through with anything just speculating options for right now

 

[ameristar1]

He's very reasonable, give him a call and he can price a regrind out for you. Personally, I think a cam swap should be mandatory for these engines, now that I got a chance to hear about the basic power curve on these engines (thanx to hesutton for that). Even if the powerband was stretched another 500 or so rpms it would make it run better, because right now the party stops at a little past 3000 rpms.

 

[spencergt66]

Well you got to remember these truck were in a market back in the day where there really was no diesel market so they had the product with little r&d involved at the time. More like the truck was produce to foe fill a select market instead of the general public unlike today where the market is vary competitive and car companies are constantly outdoing one another But like I was saying its just something im contemplating as of right now nothing is for sure on what way im going to go

 

[FordGuy100]

Can you guys explain how the cam is holding the engine out? The whole cam timing, lift, duration thing confuses me.

 

[Diesile]

Anybody know what the #ers are on the 6.0 diesel cam? That pre-07 pollution requirements engine sure goes even if it doesn't (sometimes) last.