roller cam lash question

[66torchredpro]

Just installed a herbert cam and looking at the card specs it says lash
at in. .018 ex. .020 I am assuming that is for solid roller lifters? I am using hyd. roller lifters and bought this cam as it was advertised a hyd. roller cam. Do I zero lash the lifters or go by the cam specs? Muchos Gracias!!!. :D

[BigAl713]

Thats the lash for solid lifters, like I run. Hydraulics I usually set at 3/4 turn past zero lash. I'm sure others on here will have different opinions on how much preload they run.

[66torchredpro]

Thanks BigAl, thats what I thought, just wanted to be sure.

[64PRONOVA]

You should probably adjust the preload on the hydraulic lifters to the manufacturer's recommended setting. Sounds like they sent you the wrong directions for the cam if it really is a hydraulic. I'd ask for the correct ones.

[veno]

You should probably adjust the preload on the hydraulic lifters to the manufacturer's recommended setting. Sounds like they sent you the wrong directions for the cam if it really is a hydraulic. I'd ask for the correct ones.

thats a good idea.. and have them check the cam grind numbers on the back of the cam.. to be sure you got the correct cam

[BigAl713]

Herbert lists this particular cam for use with Solid AND Hydraulic roller lifters. same grind. same specs.

[66torchredpro]

Thanks guys for the info, I will give them a call to make sure.

[veno]

Herbert lists this particular cam for use with Solid AND Hydraulic roller lifters. same grind. same specs.

Another reason I wont use a Herbert cam.

[bowtie0069]

Another reason I wont use a Herbert cam

It sounded a little strange to me at first but, a flat tappet hydraulic has different ramp specs than a solid because of trying to control the lifter--with a roller you can probably get away with a more aggressive lobe to a certain point. ??!! Did that make any sense??

[veno]

yeah it does... it tells me that herbert uses a very mild lobe profile... I can not imagine a aggressive solid roller using hyd. lifters...

if the cam is capable of using both style lifters then its a very generic profile

[66torchredpro]

Well BigAl713 says he has the same cam and it is pretty stout, but he runs solid rollers. Hopefully the hyd rollers wont make too much difference. Beside it HAS to be an improvement over the crane compucam that was bought in 1990, that I replaced. I would hope technology has much improved since then.

[straightaxlenova]

Owens cams used to have grinds that would run both solid, and hydraulic lifters. I have one in my garage now, that I have run both types of lifters. It worked very similarly,but the engine was slightly quieter with the hydraulics. It was in a very healthy street race Camaro at the time.
A friend of mine runs a Chet herbert mechanical roller in a blown alcohol altered that runs low 7s. I would think that if the cam was matched to your application, it will probably run great.

[veno]

A friend of mine runs a Chet herbert mechanical roller in a blown alcohol altered that runs low 7s. I would think that if the cam was matched to your application, it will probably run great.

Ask him if he want to run hyd rollers on it!:rolleyes:

[66torchredpro]

Well its already bought and put in. So hopefully by the end of the weekend, we shall see. Thanks for all the input guys.

[The Big Al]

yeah it does... it tells me that herbert uses a very mild lobe profile... I can not imagine a aggressive solid roller using hyd. lifters...

if the cam is capable of using both style lifters then its a very generic profile

Every cam shaft you buy out of a catalog listing is generic profile.

The only way to have a specific cam profile is to special order one that would be unique to your application. And that itself could be a generic profile.

Also get your self some cam shaft catalogs and look at the lobe specs (if given) and you will find a lot of roller cams listed in the HYD section will be the same cam in the solid section.

The cam itself may not require a aggressive profile to get the job done.
There are 2 reasons for the solid option, cost of lifters.
Solid rollers are half the cost of hyd.
And you can run more valve spring pressure with the solid.
The hydraulic advantage, quiet & no adjustments.

Also need to ask the lifter maker about the lash on the hyd. If it's a true performance HYD roller lifter in most cases the lash will be zero. Performance lifters will have stronger seats and internal springs. And too much lash will prevent the valves from closing correctly.

Al

[veno]

Hi Al,

When I say generic I mean that the lobe is cut for a hyd profile , just add solids to it..and Viola! you have a solid roller, however; if the profile is truly ground for a solid lifter then the ramp rate is much more aggressive...

If you were to install a hyd lifter on a truly aggressive ramp.... imagine what would happen to the hyd lifter plunger.... the total duration would go way down... the increased ramp speed would collapse the plunger from the extreme acceleration rate that solid rollers are known for.

to me if... I were going to spend the money on a roller... and it be a solid roller.... then I want it to have the profile of a solid roller not a bean counters dream product.

"Hey we will grind 1 cam and sell it for both apps.. solid and hyd..... the average car nut wont care... he'll have the brag effect or self assurance of knowing that "I HAVE A ROLLER CAM".... Bullshirt."

just another cost cutting effect...

JMO

Veno

[stock z/28]

Hi Guys,

I have to basically agree with Veno on this.

I would seem to me that an aggressive roller tappet camshaft that was designed for a solid lifter would really stress a typical hydraulic.

There are some special made hyd lifters available for class racers that are required to use hyd rollers that may work better, but a standard hyd lifter is not comparable in performance in my opinion to a solid roller.

Camshaft lobe designs are a very hard thing to compare in my opinion. There has been many times I have seen cams with identical specs but were ground specifically, or even ground by a different company, that had major performance differences.


The old stocker cams are kind of a good example of this. To me if you are really going to compare cams you almost need lift-to- duration specs at almost every degree or 2 to get a "feel" of the lobe acceleration at different points.

I have an old wood lathe that I converted to a poor mans cam doctor. I used an old double roller timing chain and sprocket set and used a separate brg assembly to mount the crank sprocket and an old sb harmonic balancer and a large degree wheel. Then I attached the cam sprocket to the spindle of the lathe. I know it sounds simple but this was before I had much equipment and it took a while its no pretty either. It did allow me to compare lobes on various camshafts fairly fast and a pretty accurately. I havent used it in quite a while as they changed a lot of rules, I would like to have a nice computer style one though, if any body feels like donating.:)



Good Luck Guys

Jeff

[D-Man]

Hi Al,

When I say generic I mean that the lobe is cut for a hyd profile , just add solids to it..and Viola! you have a solid roller, however; if the profile is truly ground for a solid lifter then the ramp rate is much more aggressive...

If you were to install a hyd lifter on a truly aggressive ramp.... imagine what would happen to the hyd lifter plunger.... the total duration would go way down... the increased ramp speed would collapse the plunger from the extreme acceleration rate that solid rollers are known for.

to me if... I were going to spend the money on a roller... and it be a solid roller.... then I want it to have the profile of a solid roller not a bean counters dream product.

"Hey we will grind 1 cam and sell it for both apps.. solid and hyd..... the average car nut wont care... he'll have the brag effect or self assurance of knowing that "I HAVE A ROLLER CAM".... Bullshirt."

just another cost cutting effect...

JMO

Veno


ABSOLUTELY!!!
You'll see it all over the place with SEVERAL different cam companies. The only way to really know the difference is to compare the "hydraulic intensity" of the lobes (the difference between the adv or .005" duration and the .050" duration). On a TRUE solid roller profile you'll generally see 32* or LESS split between the two and quite a bit MORE lift for a given amount of duration. That's why a true solid roller profile requires sooo much more spring pressure to control the valves!!:yes:
If you really want to get into the nitty-gritty of the lobe differences, call the manufacturer of the "Dual lifter" capable cam and ask them how they designed the "Take-up" part of the ramp so it would work with both styles of lifters. Their explanation should be quite interesting.
You'll find that ANY roller profile capable of being run with a hydraulic roller lifter and 130-150 pounds of seat pressure (typical hydraulic roller spring pressures) will have a VERY gentle lobe!! Not that it won't run good in a given application, just know you're still leaving quite a bit on the table.:devil: