My caps are loose enough to pick off with a magnet or your fingers. It allows some oiling. My caps have a tiny hole in the middle.

Lighter weight valves in a sub 7500 rpm motor don't really need 235/625# You could unshim the valves to a taller installed height of something like 1.970 for example and your springs would run cooler and last longer. Another concern is the lifter wheels. Before going to the Crane Pro lifters I had wheel bearing failure. But I was also using excessive spring pressure.

 

Thanks for the info. My installed height is 1.968".

 

Update:
T&D sent me another set of stands that were much taller (B +150) but they were too tall. Had them send me the B +50 stands and using a 0.0550 shim, the geometry was nearly perfect. The pattern location could be better centered but I am happy with the overall results.

Any opinions regarding needle bearing roller tips? Are they worth the extra cost?

 

 

Everybody has an idea about what is best. I think that the whole idea behind needle bearing is that oil can get in and lubricate better. Like high end motors even using roller cam bearings VS a flat bearing with an oil hole and groove.

Which ones are you looking at?

 

I am sending my T&D rockers in for inspection. I was thinking about having them swap out the current rollers to needle bearing rollers.

Also, do you correct the cam card lash values for rocker ratio?

I have read read convincing articles in support of doing this.

 

Yes there is science and math behind determing the correct lash numbers. But I started out working on solid roller motors back when the cam cards had big lash numbers

Those poorly designed cams just beat the crud out of the valve train and gave SR cam shafts a bad name for long term reliability. So you later started to see the lash settings get down to the high teens. Then people like me experimented with running 4-6 thou under the listed cam card without ill effects.

They have run spintron testing of race valve train under listed lash and it was determined that you have to have a certain amount of lash to make up for various heat indused expansion and binding is destructive

Right now on my. .685/.714 lift 434 sbc I have it cranked down to. 012/.014 hot which is. 004 less than the cam card using 1.6 RRs. I actually bought 8 of the 1.5s to drop exhaust lift because it is unneeded

What is it telling you to change the lash settings to

 

The cam card specified in/ex at 0.018/0.02
correcred to 1.7 ratio 0.021/0.024. Seems like a lot. I am also in the process of measuring for my new push rods.

I also updated my spring pressure info in a previous post. Apparently my springs are heavier than I thought.

 

Interesting that the formula increases the lash! Valve control rule of thumb says that spring surge induced valve float is very destructive. Too weak of springs and bad harmonics are the cause. On the other end of the scale is how destructive over kill springs are the rockers, push rod tips, lifter, and ultimately to the cam lobes and timing chain. I've mushroomed the valve tips, beat the needle bearing out of the RR trunnions, tore up quality push rod tips, lost the wheel bearing in the roller lifters. I've even seen cams that had indented wheel track on the lift sides of the lobes. Oh, even recently a shaft rocker motor was in the shop that had ground away the rocker shafts.

All these were on high rpm racing motors with excessive spring pressures. so anyway years ago I was talking to a local sprint car building motor shop about what I needed for my Dart 227 cc heads in a sub 7500 rpm motor and the answer was with your valve train weight and racing type lobe ramps start with 210 to 215# and and replace then when they get down below 195#. 1.7's are a little harder on the springs with increased lift rates, but with light weight valve train I would be afraid of 225 and replace then when they weaken to the 205# range.

Another thing that people don't think about so often is the spring rate. You can have spring "A" with 210# seat and 600# at .700 lift and spring "B" with 260# seat and 600# at the same .700 lift. The 260 pound with a .024 lash and 1.7 rockers will beat up the wheels.

Lobe design. From the Comp Cams PDF sheets on lobe designs I order the high ramp rate high .200 lift durations and the slower closing ramp to not get valve bounce off the seat in the endurance racing lobe series of profiles.

These are my two motors present cams, Both are small base circles of about .980. billet custom grinds for lobes from the PDF designed to keep the valves open for the longest time at max CFM. Starting on page 71 for solid rollers.

http://www.compcams.com/Technical/Ca...terCatalog.pdf

 

So what do you consider excessive spring pressures?

 

Are you running new AFR eliminator heads with the small stem light weight valves. Tony Mamo posted on here about his new business and gave a link. He might be the true person to ask because he was in development of AFR heads for years.

I also use dual springs that are about $500 a set in my vette motors, so they have some superior harmonic properties and when I was racing replaced them kinda annually. I run taller installed heights to decrease seat and open pressure and have had good luck with longevity.

 

Tony designed my cam and set my heads up.

 

What is your max rpm?

 

7000

 

Yes I would say that those springs are VERY excessive for light weight valves and such low rpm of only 7000 and lifts of only low. 700s

Your installed height of under 2.00 inches would be slightly more than 250# seat and over 700# at your max lift. That is the type of springs used in 8600 rpm sprint car motors with .800 lift that might last a season

1.7 rockers with big lash gaps and big spring pressures is what destroyed your valve stem caps.

 

AFR have been using smaller diameter valve stems for some time and you need to get the corrct lash caps or you will run into problems. You can't use the ordinary small block lash caps, they are too big.
Also the T&D rockers are designed to have the rocker roller tip to be straight across to the valve tip resulting in all the pushrods being in a perfect straight line from the lifter to valve pushrod pocket. One of the big problems with the shaft rockers is getting them aligned properly. I had to send mine back 2 times before I got the correct set.

 

I am not sure I understand your comment regarding push rods being in a perfect straight line. The problem I had is getting a stand of the correct height to ensure proper rocker to valve geometry. The method for measuring push rod length is fairly straight forward. The only other thing that I can see you have control over regarding component alignment is the stands themselves once the mounting bolts are installed lose, can be slightly moved from left to right (Very little). I just move it until all rollers are as centered as possible (Left to right) over the valve tips. The gauge supplied by T&D for shimming the rocker stands basically locates the center line of the roller tip axle and rocker shaft (fulcrum) to be 90deg to the valve at mid lift. See the attached PDF. The PDF uses just a small machinist T-Square to accomplish the same thing. The attached PDF also takes into account the valve lift loss due to the lash. This results in a net total lift value that is used to determine the gap between the square and valve tip at the valve closed position. All this precision is well and good but I find it funny that T&D only offers shims at .03 and .06. Kinda makes it hard to dial in. Better measure these as well.