Don't you install new lifters during a cam swap? I know you do this in gaser, so why not in the cummins. In my youth I installed a cam in a 360 dodge with the original lifters, couple of the lobes went flat in pretty short order. Also is the cam gear locked into place with a key? I remember seeing that you can buy offset keys to advance/retard the cam. I remember when I degreed my gaser engines in the past I always checked the valve to piston clearance, is this an issue with the cummins. I thought that the EGT's and turbo spool-up benefits came from the increased valve opening duration. I would think that you would see a slight decrease boost due to the valve being open longer.

 

With roller lifters, you don't have to change the lifters whenever you change cams. Flat tappets you do.

 

I thought that cummins uses solid lifters?

 

they do

 

They are solid flat tappets. But not really flat. Kinda flat. As flat as you can see flat, but really not flat, flat. Slightly convex. Ever so slightly convex. Thats why I hate reground tappets in the Cummins. They were designed to rotate in their bores. Thats why they are convex. The rotatng tappets take a good oil to make them rotate and not wear the bores out in the block. That oil was speced by Cummins when they went to "rotating followers"

New tappets only. Its hard to duplicate the convex curve back again with regrinding. Or you could run the older style flat tappets, but the wear is higher on the camshaft. As the tappets rotate they minmize the wear. Quite a bit actually.

Don~

 

I remember reading some where that the aftermarket cams have the same lobe separtion as the stock cam. So is an aftermarket cam really advancing the cam timing? I planning a cam swap this summer but the aftermarket cam info is really lacking for cummings engines. When I install the new cam, I was planning on degree my cam to 0 degrees. I haven't figured out on how to do this yet but it would be some good research to determine how much affect that this would have on the overall engine's performance.

 

The aftermarket sticks seem to be widening the overlap up some. I cant say who has how much, but stock is generally about 105-106 degrees. I cant say how much if any, the aftermarket sticks advance the timing of the events compared to stock. I dont know.

 

Seems like a fellow told me a couple of years ago that the marine was 108 lobe center and the engine that is used in the dodge was 106. This may not be correct as I dont hear good as I once did. Jim

 

On 460 and 429 Fords I used to advance one whole stock chain tooth. Gave it brutal bottom end and got weak just before leaving passing gear on the auto. Picked up the mileage a little and made a fun engine to drive in the pickup. V6 Buicks handled a full tooth also with the same results.

 

does anyone have the card specs for a stock cam, and for a aftermarket. duration, lift, seperation, ivo, ivc, evo, evc.

 

98 2500, for almost 3 years now I've been asking for cam specs, stock and aftermarket, and either no one has them (HIGHLY unlikely), or they don't want to give them out. A little birdy told me that stock lift is around .200-.300. That's all I know.

 

I think that what you are saying is right on the money. Bits and pieces. I am only assuming and you know what that means, that the stock cam is 106 and the marine is 108 and the aftermarket is 112 lobe center. I dont know for sure and it just a guess. Even if I knew what a vendors specs is, I would not say as it would not be right.
I just wont to know what a stock 12 first and second generation and 24 valve and the marine camshaft specs are. Why did cummins do what they do. I have heard of guys using marine camshafts early on as they may have been better. Some say yes and others say no there.
Camshaft - Bits and Pieces> Should have more lift and intake duration, Give the cylinders more time to fill. This will wake up the bottom end and mid range torque,while spooling better.
However if you increase overlap you create pumping losses and boost is reduced, futher more the fresh air injected into the stream of fuel rich exaust too late will cause high egt.
The marine camshaft had a different gear to drive it( only fits Marine ) a long bolt holds it on the gear and a woodruf key is used also, I have heard that the Marine camshaft is 15hp gain in the 215 engine. That is what happened at first, again I only assume here and the aftermarket camshaft was developed a little later.
This may not be correct so please jump in if it is not . Jimk

 

The Marine cam in the 215 engine will net you a loss of around 50 HP.

 

Stock 12 valve 215 engine:

Intake lift is .235
Exhaust lift: .263
Intake duration is in the 155 range
Exhaust is in the 200 range

Stock 24 valve:

Intake lift is : .235
Exhaust is : .296
Duration is close to the 12 valve.

Now that you know. What would you do?

Don~

 

Add it to the rest of the information. As a side note the marine camshaft losses is what a fellow said also after he installed it. As he was not to happy either. Jim