Black diamond valves

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jseng1

jseng1

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Do Black diamond valve tips have the same pitting & wear problems as stock valves? Do they need lash caps as well?
 
Black diamond valves come with a stellite tip already installed. But they are only available in Commando lengths. Jim
 
comnoz said:
Black diamond valves come with a stellite tip already installed. But they are only available in Commando lengths. Jim
Click to expand...

True, but they will make them up for you in custom lengths if you so desire. I've had them make up Black Diamond valves in a variety of special sizes. They are a bit more expensive in custom sizes, but not rediculously so.

Ken
 
I fitted the BD's with lash caps.
Think I had to shorten on the lathe either the exhaust or inlet, cannot remember.
Have set it up so that rocker was perpendicular to stem at halfway valve travel.
 
lcrken said:
comnoz said:
Black diamond valves come with a stellite tip already installed. But they are only available in Commando lengths. Jim
Click to expand...

True, but they will make them up for you in custom lengths if you so desire. I've had them make up Black Diamond valves in a variety of special sizes. They are a bit more expensive in custom sizes, but not rediculously so.

Ken
Click to expand...


Very true, I just got some custom valves for a Duc. But why would you want shorter Norton valves when the long Commando valves are barely long enough to give decent valve train geometry? Jim
 
The caps give, though not a lot, some extra length.
I assumed geometry would be optimal when perpendicular halfway, maybe it is not.
Anyway, that is why I had to take a bit of.
I remember now I also had to add length to the pushrods.
I wrote it down what I did but lost it.
Shimmed the rockers at the same time.
 
slimslowslider said:
The caps give, though not a lot, some extra length.
I assumed geometry would be optimal when perpendicular halfway, maybe it is not.
Anyway, that is why I had to take a bit of.
I remember now I also had to add length to the pushrods.
I wrote it down what I did but lost it.
Shimmed the rockers at the same time.
Click to expand...


Perpendicular at half travel is the way I have always done it. If you put in a cam with more lift then you need extra valve length to keep that relationship. In actuality I just use the long Command valves and find they are close enough to not give problems in most applications. Jim
 
While undergoing my complete rebuild recently, I put in a new Megacycle 5600 cam with higher lift and slightly oversize Black Diamond valves.

The valves were just touching, so had to have 10 thou take off all around and recess the seats a bit into the head.

Perhaps should not have been unexpected, but it was, and also cost an additional $400 to have the valves and seat recesses done properly.

Doing a complete rebuild was a lengthy and expensive job, but along with Jim Schmidt's new flat slides, well worth doing!
 
comnoz said:
Perpendicular at half travel is the way I have always done it. If you put in a cam with more lift then you need extra valve length to keep that relationship. In actuality I just use the long Command valves and find they are close enough to not give problems in most applications. Jim
Click to expand...

Its not very practical to make longer valves for race cams.

With higher lift couldn't you just shorten the pushrod? Because the valve will be pushed further down and so the geometry has changed. It changes geometry when the valve is on the seat but this seems like a good compromise.

So if you have .080" more valve lift then you would want .040" shorter pushrods correct?

Jim
 
Hi there, I will fit black diamond valves and had mushroom , so I expect that the lash caps will help to spread more evenly the load, though I will have soon the Jim Schmidt camfollowers which should reduce the stress on the valve train.......is someone knows the lenght added by those lash caps....? cause I need to order the pushrods from JS and thus telling him the correct lenght (my head will be an RH6 so it will be milled 0.020" from stock , not saying that my buddy will transform it to accept the Maney jugs as per Ken Canaga pics ,and some milling will be done at the end of the work to flush down the possible recess of the inserts...........)
Thank you to Ken and Jim for their nice cooperation.
 
panic said:
Removing a fixed amount equal to the head mill is only helpful if:
1. this is the only modification
2. the geometry was perfect before (no wear, aftermarket replacement parts, seat recession)

If the cam is changed, in theory the pushrod length should be shortened (in addition to any correction made to cylinder head or barrel height) by 1/2 of the added lobe height (not lift).
Example only:
Original lobe .350"
New lobe .400"
Difference .050"
Shorten pushrod .025"

However, this is only true if the base circle (zero lift) is unchanged.
Since the cam manufacturers, when asked "do you reduce the base circle by 1/2 of the added lobe height to correct the geometry?" answer (quoting, literally) "................................................ what?" you won't know what you have unless you either mike the new cam for both base circle and lobe height and compare it to an NOS or perfect cam, or (better) assemble the engine with the new parts and analyze the geometry.
The welded hardface cams such as Norris and Web-Cam probably use the stock base circle - but I don't know this as fact, it's just more likely.
Reground cams (no weld) cannot use the stock base circle, because the new lobe profile and height are produced by removing metal from the base circle - there's no other way. A change of duration, lift, centerline or any combination of these will always reduce the base circle diameter.

Warning: analyzing the geometry is one of the most misunderstood, badly diagnosed problems on the net. Everybody and his dog thinks it's simple to understand, the original factory stuff was fine, and that it can all be handled with adjustments and/or pushrod length.
Wrong, wrong, wrong.
Rather than give you 10,000 words (no, I'm not kidding) if you assemble the engine some of the easiest things to look for are:
1. adjuster runs off the tip (duh)
2. can't get an adjustment
3. angle for valve closed (lift = 0) is completely different from valve fully open (lift = 100%)
4. the adjuster only moves in one direction during the lift
5. adjuster does not pass through the center of the stem tip during lift

The "correct" geometry is perceived to be when a(n) (imaginary) line drawn between the adjuster contact point and the rocker shaft centerline is at 90° with the valve stem axis at 50% lift. This is called the "mid-lift" or "Miller" method, and it's not the only method, not necessarily the best method, but it works and is the easiest to plan and measure.
If this is correct, the adjuster's "scrub path" or what pattern it makes on the stem during lift, will start slightly inboard (closer to the shaft) of the valve stem tip center at 0 lift, walk across (away from the shaft) until 1/2 lift, then walk back. If it does not do this, it's wrong.
The positions need not be centered (far less important, and cannot be cured by adjustment anyway), but stopping and reversing at mid-way is key.
If you can't actually measure this, anything that shortens the length of the scrub path is good.
You can simulate a shorter pushrod by shimming the rocker box up, use the smallest increment shims your patience will stand (.005" is a waste of time, .060" is too big).
You can simulate a longer pushrod by placing a small piece of metal scrap between the tappet and pushrod end, or pushrod and rocker end. I suggest aluminum, since you can easily dent it with a punch to match the curvature. Cut a small circle, then saw a slit from 1 side to the center to make it easier to dent.

Found that from Panic few times ago......
Click to expand...
 
jseng1 said:
comnoz said:
Perpendicular at half travel is the way I have always done it. If you put in a cam with more lift then you need extra valve length to keep that relationship. In actuality I just use the long Command valves and find they are close enough to not give problems in most applications. Jim
Click to expand...

Its not very practical to make longer valves for race cams.

With higher lift couldn't you just shorten the pushrod? Because the valve will be pushed further down and so the geometry has changed. It changes geometry when the valve is on the seat but this seems like a good compromise.

So if you have .080" more valve lift then you would want .040" shorter pushrods correct?

Jim
Click to expand...

Sure you can shorten the pushrods, but then you need to lengthen the valves to get the adjustment back in the same spot. Screwing the adjuster out messes up the geometry of the rocker.

I made a rocker arm to fit in a Norton head that had a machined perpendicular flat that layed against the side of the valve. It had a lip for the top of the valve that was level with the rocker pinion centerline. Using that I was able to find the correct valve length. Stock Commandos were very close. If you add .100 lift to the cam then the valve needs to be .050 longer and the pushrod needs to be around .040 shorter. If the base circle stays the same and the head and barrel stays the same and the lifter is not reground,and the valve is not pocketed, ECT.

If you want it right it needs to be measured on each one. Jim
 
That is where caps come in handy.
I got mine via via through RGM, they fitted real snugly over the stem.
Had to grind and polish the top surface a bit.

Marinatlas, these mushrooms, what make them "superior", do they have a larger radius than standard adjusters?
Or do the edges of the standard ones strike the valve on occasions?
 
You can simulate a shorter pushrod by shimming the rocker box up, use the smallest increment shims your patience will stand (.005" is a waste of time, .060" is too big).
Click to expand...
This equivocates to a thicker head gasket on a Norton as there are no rocker boxes like a car engine with bolted down rocker shafts.

Lets not forget the Norton rockers are a 1:1.13 ratio meaning the distance from pivot point to push rod cap is different than the distance to the pivot point to adjuster. When the push rod moves a distance of 1 the valve moves 1.13. (that's why in the Norton specs and Jim's example above the push rod length adjustment is always less than 1/2.)
 
While we are having fisticuffs over valve geometry, how the hell do they reangle the guide and then get any thing to line up :?:
 
You do that by keeping the top of the valve stem in the same place and just moving the head of the valve. It certainly does not improve the valve train geometry however. And increasing the bend in the port doesn't do much for the flow capability either. Jim
 
elefantrider said:
You hear a lot about them, so do they greatly extend the life between valve jobs?
Click to expand...

1. If they are used with the correct valve guide alloy, the coated stem provides a very long wearing stem to guide interface. The coating does not do much good in a cast iron guide.

2. They have a welded stelite tip which keeps the adjuster from wearing into the tip as fast as a plain steel valve.

3. They are a good grade of stainless which helps with valve to seat wear.

4. no welded on head means they can't break at the weld.
 
Ok. Sounds like the way to go then, especially if used with Bronze guides.
Anyone have in stock Diamond Valves for an Atlas motor? I assume they just be can be swapped out against the plain steel valves if the valve job is still fresh, and guide to stem clearance is the same. Not sure if the special coating adds to the stem thickness vs. stock valves.
 
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