Exhaust Valve Rotators?

[buddy]

Hello, I was wondering if anyone that has tore down or built up a head noticed if the exhaust valves have rotator retainers, or all just regular retainers on the valve springs?

The 6.5 diesel has the rotators, but I was wondering if GM continued using in the diesel trucks? It wasnt common on the cars, but might be necassary on the heavy loaded trucks.

Thanks for any info.

 

[THEFERMANATOR]

There wasn't any in my LB7 when I had it tore apart.

 

[buddy]

Thanks, I know most performance engines eliminated them because they couldn't handle high pressure springs, and they are not on the recent or new GM passenger car V8s.

I wonder if the Dmax valves made out of stronger,more heat tolerable material than the 6.5 valves.

I saw MaxPF did a 6.2 buildup with bigger springs, and used BBC rotators that actually went under the valve springs, that is now MikeyVonn's engine. I was thinking of just eliminating them.

 

[3500GMC]

I chose to keep the exhaust valve rotators. I thought about the heat and wear properties of the exhaust valve. Maybe it's just redundant old school tecnology that paranoid engineers used to employ. I dunno. :dunno:

 

[robzombie4551]

I say throw'em away, they just take up weight and space.

Who needs stinkin rotators, they only spin the valve to keep them from taking all the heat in one spot, and keeping valve guide wear in check.

Way over rated them rotators are. LOL

 

[buddy]

If the Dmax dont need them, the I must not.

The rotators aid in the rotation obviously, but that force on the spring will still be there causing the same rotational torque, it just wont rotate nearly as much per compression. Or I could look into these larger BBC rotators like MaxPF used, since no rotators are available as retainers in the size I would need, and the retainer rotators dont work with dual springs.

 

[6.2 turbo]

I didn't use them on my 6.2,but had to shim the springs to compensate.

 

[buddy]

I didn't use them on my 6.2,but had to shim the springs to compensate.

Is the installed height 1.8" without the rotator or with it? Because I got beehive springs that make plenty of seat pressure at 1.8" install height with no rotator. So although I planned on using a double thick "stronger" spring seat cup or "locator" under it, wasnt planning to shim it.

I was reading up on Stellite and Inconel, because our exhaust valves are made of Stellite, and Stellite is a harder material that Inconel which many of todays exhaust valves are made from. Perhaps differnt alloys of Inconel are superior to certain Stellite alloys. The use of these more heat and wear resistant metal alloys appears to have reduced the necessity of the rotators.

 

[6.2 turbo]

With everything stock the intake and exhaust have different spring installed heights . I think it would be close to 1.800 with the rotator. I can double check tonight.

 

[buddy]

With everything stock the intake and exhaust have different spring installed heights . I think it would be close to 1.800 with the rotator. I can double check tonight.

Thanks, that would be very good to know, if I will need a rotator eliminator (thick shim, but with the "spring locator")

 

[THEFERMANATOR]

Exhaust valve rotators started back in the 70's when emissions came abouts. They were used to clean carbon deposits off of the exhaust valves by spinning them on the seat and breaking the carbon loose.

 

[6.2 turbo]

The heads I'm working on now are 1.830 intake and 1.860 exh this is not counting the upper shroud or any shims on the bottom . The stock shims I think are .030, same for the oil shroud . I checked some other well used 6.5 heads and they were 1.870 intake and 1.880 exhaust. My readings may be off a little since they all had springs installed,and the valves may be sunk in the head from wear also.

 

[buddy]

That makes it seem like the stock setup is pretty weak seat pressure, around 60psi, with springs rated for a 1.8" installed height with 80psi pressure and like 375 psi/in rate. With the stock cam having so much negative overlap I suppose that works alright. I'd like to maintain over 100psi seat pressure after break in with the beehive springs I selected that are rated as 130psi at 1.8" installed height and 313 psi/in rate.

I'm hoping the roller rockers and lighter springs and retainers help improve performance and efficiency.

 

[6.2 turbo]

Should help in higher revs at least .

 

[THEFERMANATOR]

That makes it seem like the stock setup is pretty weak seat pressure, around 60psi, with springs rated for a 1.8" installed height with 80psi pressure and like 375 psi/in rate. With the stock cam having so much negative overlap I suppose that works alright. I'd like to maintain over 100psi seat pressure after break in with the beehive springs I selected that are rated as 130psi at 1.8" installed height and 313 psi/in rate.

I'm hoping the roller rockers and lighter springs and retainers help improve performance and efficiency.

Theres no reason to run that kind of seat pressure on a 6.5. You will be COSTING yourself HP by doing so. The CUMMINS guys run 60# seat pressure springs and turn them up close to 5K RPM's at 50 pounds of boost without much issue at all. I couldn't see any reason for naything more than that for a 6.5.

 

[Pepperidge]

I wonder if the Dmax valves made out of stronger,more heat tolerable material than the 6.5 valves.

Inconel...but only the exhaust valves IIRC

I was reading up on Stellite and Inconel, because our exhaust valves are made of Stellite, and Stellite is a harder material that Inconel which many of todays exhaust valves are made from. Perhaps differnt alloys of Inconel are superior to certain Stellite alloys. The use of these more heat and wear resistant metal alloys appears to have reduced the necessity of the rotators.

see above

 

[buddy]

Depends on what I will be using for lift and duration on the cam, and valve clearance to the pistons. This isn't going to be a stock 6.5. Although the seat pressure will be a little more, the open pressure will only be a little more than the stock spring would provide, because the spring rate is lower.

 

[6.2 turbo]

Theres no reason to run that kind of seat pressure on a 6.5. You will be COSTING yourself HP by doing so. The CUMMINS guys run 60# seat pressure springs and turn them up close to 5K RPM's at 50 pounds of boost without much issue at all. I couldn't see any reason for naything more than that for a 6.5.

The Cummins 60 # springs are rated for 60 lbs drive pressure not seat spring pressure. My Cummins has stock springs and I would say they have more seat pressure than a 6.5 . Also the 6.5 has hydraulic roller lifters,which can take as much or more, seat pressure as a solid flat tappet,minus the wear.

 

[buddy]

From what I can find seat pressure on the Cummins "60lb" springs is 115psi, for whatever reason. They also make a set of beehive springs for the Cummins that are 110psi seat pressure.

And although Heath and some others have found the stock springs are good to 5000rpm, that wasn't with the cam grind I have going in, and I am more concerned with any valve float or whatever you also call where the backpressure on the exhaust valve and the gasses being pushed through could keep the valve from seating before the piston gets there at high RPM.

 

[buddy]

Inconel...but only the exhaust valves IIRC

Thanks, there definately inconel valves available, I asked a vendor who mentioned the stock ones are stainless steel. Although I would have to guess they are stellite or similarly coated. If they are stainless I would think the inconel exhaust valves would be highly desired. It should be that stock.