99+ cam

[SilverXJ]

I'm an engine noob and I find this convo interesting. I had to think about this for a bit but I *think* I've wrapped my head around it. My understanding is that the larger diameter lifter will allow more duration ("travel time") of the cam lobe against the lifter. More duration can be combined with a fast ramp rate to get the valve open as fast as possible and as long as possible, and possibly more lift?

Sort of correct. Not really more duration, but more or sooner lift in a shorter duration. It will get the valve off the seat quicker.

Biscuit, if you foresee extended periods of idling with your stroker, take an honest look at the power levels you really want vs reliability in your cam choice. Reading over your posts on how you expect to use the engine the majority of the time, I would offer a recommendation to try and keep it in line with a milder build. *I don't mean to contradict any advice you've been given by others on the site, or those you've enlisted to build your engine.* Oil-sling to the cam is your friend on these engines, and its minimal @ idle rpm. Higher lift cams wont do you any favors in regard to extended idle reliability. Something closer to stock lift levels might do you favors in the long-run. Idling is less of an issue once the oil is up to temp, but not so healthy on a cold engine where oil circulation & lubricity are reduced. Even though the 4.0's put up with it without a fuss, I would be cautious. Only my 2-cents. Good luck on your build and your search for optimal components & peace of mind.

All very good points. Low rpm long idle(little splash) + an aggressive cam = short cam life. Hesco had a customer that was killing their RVOB cams in short order. After 3 or so dead cams he finally mentioned long idle periods while warming the Jeep up in the morning. Not a good idea. He stopped doing that and the cam lived.

[Cheromaniac]

Low rpm long idle (little splash) + an aggressive cam = short cam life.

Since the rod bearings were changed a few years ago and the newer ones no longer have a hole that allows oil to be squirted onto the cam from the rod big ends, the cam now relies solely on splash lubrication by oil draining back from the head down the pushrod holes. As you rightly pointed out, at low rpm there's isn't much splash lubrication especially in the first few seconds after start up.

[biscuit]

it seems i have some trade offs to figure out. the thing is, in the winter i use an auto starter to warm up the vehicle. i am really fond of the thing. since i know i will be using it, i am trying to get the cam situation figured out.

1. lifter bore grove. won't that help out tremendously?

2. wider .67 lobe. should help out

3. under .5 lift. a little aggressive, but not crazy.

4. nitrided cam. didn't want to do this, but should i? + $100.

with those 3 things, and possibly the nitride, does anybody think i can handle say a daily 10 min start up cold idle? or are my autostart days over???

[jeepxj3]

http://www.accusump.com

[SilverXJ]

it seems i have some trade offs to figure out. the thing is, in the winter i use an auto starter to warm up the vehicle. i am really fond of the thing. since i know i will be using it, i am trying to get the cam situation figured out.

1. lifter bore grove. won't that help out tremendously?

2. wider .67 lobe. should help out

3. under .5 lift. a little aggressive, but not crazy.

4. nitrided cam. didn't want to do this, but should i? + $100.

with those 3 things, and possibly the nitride, does anybody think i can handle say a daily 10 min start up cold idle? or are my autostart days over???

10 minutes shouldn't be too terrible. The guy hesco mention was doing it for around 30 minutes. A few suggestions. Use an engine block coolant heater, maybe an oil heater as well. Much better in all respects than the remote start and it keeps your engine very happy as well. Sure you will have to plug it in but its worlds better than remote start in all aspects. I would go with an in sump heater and the coolant heater. If you do run the remote start I suggest using the high idle feature on your PCM. There is an unused pin that if you ground it it bumps the idle to 1000. If you know what you are doing with your remote start you should be able to wire it so that it only comes on with the remote start. I'm not convinced of nitriding.

http://www.accusump.com

I am not sure what this would do for his remote start or engine heating.

[jeepxj3]

Using a solenoid valve, it would provide the needed oil at initial start and first 5-10 minutes. It would also provide oil if low pressure exists during running, idling, turning, etc.

[biscuit]

slick trick on the pcm high idle, thanks, something tells me. that if i do that, and a custom tune on the pcm.... it may be possible to raise the rpm on the pcm high idle pinout. i got till winter to figure that one out....

regarding the accusump thing. my sump wont be running dry, but the low rpm's will not allow the oil splash action. thats where the bore groove idea may help.

regarding nitriding.. i am not convinced there either. the glazing that happens when the zddp adheres to the cam/lifters under heat/pressure, seems to be a good o'l surface treatment. and it doesn't cost an extra $100.

the sump heater is a good idea as well. i have months to prepare for winter. i have about a week to figure out my cam selection.

btw the autostart is more to keep me warmed up than the engine... gets cold in the ST. Louis area when your from the west coast.

[SilverXJ]

Using a solenoid valve, it would provide the needed oil at initial start and first 5-10 minutes. It would also provide oil if low pressure exists during running, idling, turning, etc.

That system doesn't work like that. First it only supplies enough oil for a few seconds. 10 minutes would take a massive reservoir. Then it wouldn't help to just run the oil from the reservoir into the oil system. You would need jets pointed directly at the cam itself. Its nor about pressure, but about splash which you need the RPMs for.

slick trick on the pcm high idle, thanks, something tells me. that if i do that, and a custom tune on the pcm.... it may be possible to raise the rpm on the pcm high idle pinout. i got till winter to figure that one out....

Yes, according to Chris it is possible to raise the RPM on the high idle. However, I wouldn't venture much above 1500 rpm.

regarding nitriding.. i am not convinced there either. the glazing that happens when the zddp adheres to the cam/lifters under heat/pressure, seems to be a good o'l surface treatment. and it doesn't cost an extra $100.

I would ask Jones his opinion about the nitriding as he does offer it. The one cam that I had lobes go flat on was a nitrited comp cam.

the sump heater is a good idea as well. i have months to prepare for winter. i have about a week to figure out my cam selection.

If you are going for a sump heater you will want to have the bung welded in while the engine is out and oil pan is off. Other wise you would have to drop the oil pant o have the bung welded on. You can get those stick on pads, but the in sump style is the most effective.

btw the autostart is more to keep me warmed up than the engine... gets cold in the ST. Louis area when your from the west coast.

Block heater and oil heater will give you instant heat. IIRC the coldest day here and my coolant was up to 120* with just the coolant heater on for 4 hours. Your engine will also thank you.

[CandyCaneXj]

Yes Hughes engines makes wide lobe camshafts for our engines. I just called them...lobe width is .67. That's what "real Chrysler lobes" mean.

No that is not what "real chrysler lobes" mean" It means lobes that have a profile to take advantage of the wire diameter lifter. However, that .67" is a wide lobe. Once you understand why the larger diameter lifter matters then you will under stand what makes the Mopar profile different and has little to do with the width of the lobe.

Wide lobes. Ramp rate is much faster on these because the wide lobes are stronger and can handle it.

Incorrect. A fast ramp rate cam be accomplished on a narrow lobe cam as other cam manufactures (which Hughes is not) have done for years.

All this was explained in the first link I posted.

The link to Hughes you provide mentions nothing of wide lobes. It makes mention of the wider lifter.

However, grinding a profile to take advantage of the Mopar lifter is nothing new. Many cam companies do that including Jones, lunati, ultradyne, etc. This is from Ultradyne: http://www.bigblockmopar.nl/tech/ultradyne-cam-specs/

Hughes told me they call them real chrysler lobes because of the profile yes but also because of the lobe width. They don't recommend true .904 profile on a narrow lobe. I understand that other companies have this aggressive profile to match the .904 lifters but those cams are not as durable. How could anyone feel comfortable running a fast ramp rate which requires stiffer springs on a weaker .5 lobe camshaft? Thats like living a normal life then shaving part of your knee off(narrower lobe) then adding a 5lb weight(stiffer spring) on your head then making the steps in your house steeper than before(more aggressive profile) and then you continue living and expect yourself to be just as pain free as before . My understanding is that a lobe width of .67 is going to have 33% more lobe to lifter contact area at all times than a lobe of .5. And also more even lifter wear and on top of that the ability to run stiffer valve springs. Correct me if i'm wrong? So yes I consider this to be a big step up from a narrow lobe.

[SilverXJ]

Hughes told me they call them real chrysler lobes because of the profile yes but also because of the lobe width.

I'm not interested in what Hughes is calling it.

My understanding is that a lobe width of .67 is going to have 33% more lobe to lifter contact area at all times than a lobe of .5. And also more even lifter wear and on top of that the ability to run stiffer valve springs. Correct me if i'm wrong?

That isn't how it works. You won't get 33% more contact just because the lobe is that much wider. The lifter never contacts the full face of the lobe because a) the lobe is tapered and b) the lifter is domed.

[jsawduste]

Hughes told me they call them real chrysler lobes because of the profile yes but also because of the lobe width.

I'm not interested in what Hughes is calling it.

My understanding is that a lobe width of .67 is going to have 33% more lobe to lifter contact area at all times than a lobe of .5. And also more even lifter wear and on top of that the ability to run stiffer valve springs. Correct me if i'm wrong?

That isn't how it works. You won't get 33% more contact just because the lobe is that much wider. The lifter never contacts the full face of the lobe because a) the lobe is tapered and b) the lifter is domed.

Thanks Chris for sticking to the facts and not pussy footing around the subject.

I have purposely stayed out of this hoping the contact patch would be bought up..

[CandyCaneXj]

Yes it looks part way up and down the lobe the lifter does not make full contact with the lobe. But it makes full contact at max lift. Here is a picture of two different 1998 cams I have in my garage. Both with the exact same wear. In the middle at full lift it makes full contact judging at the wear. So If a half inch lobe has this same pattern it's still getting 33% less lobe to lifter contact than this...

[SilverXJ]

Yes it looks part way up and down the lobe the lifter does not make full contact with the lobe. But it makes full contact at max lift. Here is a picture of two different 1998 cams I have in my garage. Both with the exact same wear. In the middle at full lift it makes full contact judging at the wear. So If a half inch lobe has this same pattern it's still getting 33% less lobe to lifter contact than this...

You see the wear pattern all the way across the cam lobe because the cam or lifter is either worn or it was moving around in the block.

If you see a wear path on the cam that is greater than 1/2 the diameter of the lifter you have worn components. The lifter has a dome on the foot and the cam lobe is tapered.


You can clearly see the wear path on a low mileage cam that does not go all the way across the lobe peak.

[CandyCaneXj]

I see the half inch wear on yours and can understand how mine look more widely worn which I suspect is from worn out timing cover buttons. Thank you from pointing that out I did not think of cam front to back movement. I still have to wonder if the .67 lobe is more forgiving on a high milage engine. If it eventually wears on the whole thing would that mean if it was a narrower lobe it would have worn more because the wear is not as spread out sort of say?

[SilverXJ]

I see the half inch wear on yours

It is less than 1/2" inch as those are the earlier narrow cam blanks.

and can understand how mine look more widely worn which I suspect is from worn out timing cover buttons.

COuld be from the cam walking, but I'd also be inclined to believe it is also from cam lobe and lifter wear...Its hard to see the rest of the lobe, but if its cam walk you should see a thicker band all the way around the lobe.. but it still wouldn't rule out lobe or lifter wear.

I still have to wonder if the .67 lobe is more forgiving on a high milage engine. If it eventually wears on the whole thing would that mean if it was a narrower lobe it would have worn more because the wear is not as spread out sort of say?

I do believe that the wider lobe does contribute a good deal of extra surface for the lifter to ride on. It is just not 33% as you had said. The wider lobe should be ground with the same degree of taper as the narrow load but spread out over a greater distance giving the lifter a larger spot to ride on.