Lash caps after cam mod

[Idaho Red Rocket 3]

He needs longer, shaving stem and valve seats cut gets him even wider clearance than what he has now. But new valve seats that will get him up

Kevin when you cut the valve seats the valves go deeper into the head and the valve stems come up closer to the cam reducing the gap. So a thinner shim is needed.

 

[Valaas]

Kevin when you cut the valve seats the valves go deeper into the head and the valve stems come up closer to the cam reducing the gap. So a thinner shim is needed.

If I understand the manual correctly you can't change valve seats on these heads, they are hardened and ment to outlast the engine.
I want to avoid cutting seats, also for that reason

 

[Kevin frazier]

Kevin when you cut the valve seats the valves go deeper into the head and the valve stems come up closer to the cam reducing the gap. So a thinner shim is needed.

Thats right, i understand what you were saying now. Dislylexia is real

 

[Valaas]

Summary:
Is lash caps an option for the RII? Yes.

Lash cap used: 5.50mm ID, 2.50 mm cap depth, builds 1.10 mm to the valve stem

Valve stem can be seen without cap here

Here with cap on top of stem, resting on the stem, not the lock ring

Cap matches well the bucket counterpart and simply elevates the bucket 1.10 mm:

After fitting new shims based on calculations from gap measurements of, to me extremely large, gaps (0.90+), fitting ladder and rotating cams sufficiently to ensure shims were in place, I measured again. Yes, I missed by between 5-10/100mm's on quite a few, (4 of 6) but I feared far worse results. Waiting for shim replacements and expect the next measurements to be within tolerance.

Disclaimer: I have not had the engine running with these 6 intake lash caps installed yet. If I end up with X ounces of shavings instead of valves after startup, I will edit this post instantly and extensively.

 

[Neville Lush]

The shim bucket in your picture is about to sh_t itself. If you need to add lash caps there is something going on. Maybe your cams have been ground with a smaller base circle???. Maybe remove the cam and measure base circle and lift with a set of calipers, it won't be dead accurate, but close enough.

 

[Valaas]

The shim bucket in your picture is about to sh_t itself. If you need to add lash caps there is something going on. Maybe your cams have been ground with a smaller base circle???. Maybe remove the cam and measure base circle and lift with a set of calipers, it won't be dead accurate, but close enough.

Hi Neville, smaller base circle/heel is alreeady given I would think as I had to increase shim thickness by 0.90mm+ all over the intake side. But what is your concern about the caps? It is just an extention to the valve stem, if anything with a larger area to apply force on the bucket.?
I'll measure lift after i get the new replacement shims (cams at TDC, measure lift directly on the valve on cyl 3). What value should I ideally see?

 

[Neville Lush]

I guess my concern is that a lash cap is a 1950 style thing. The lash caps will gradually wear a groove into the end of the valve stem, but it may not be an issue for you as you probably aren't going to do big mileage. If the cam is a regrind, then they must have done some serious stuff on it to lose that amount from the base circle. Is your bucket ok, in the picture it looks like pieces are breaking out of the inside???

 

[DesertRat]

Hi,
after street/FA cam mod I need up to 3.63 mm intake shims, which seems difficult to source.
I can get lash caps, but I cannot find any post confirming this is a viable option.
Q1: Lash caps - viable option?
Q2: I measure the top of the valve stem (valves are not out yet, waiting for proper valve tool to arrive) dia to 5,5mm. Can anyone conform this is correct?

Rocket III Classic 2008

TIA
Inge

Have you spoke to the Maker of the Camshaft?

Usually a Camshaft Maker will tell you if their aftermarket Cam Profile works with OEM Valve Geometry and/or what Mods are needed.

Btw are using a Degree Wheel?

 

[DesertRat]

I assume this is a used/worn in engine?

Did you verify that the other Valvetrain items are within OEM spec or have been replaced New?

An out-of-spec/worn Cam Gear, Cam Chain, Cam Idler can cause what you believe to be TDC to be off by several degrees.

Btw, Its very difficult diagnosing via a one-dimension web-page/pics.

Too many possible variables.

 

[DesertRat]

Prototype Performance cams for the Rocket.

I've now got the reground cams back from my cam company. We running about 0.7mm more lift and increased duration. We are just finishing up re shimming the last two valves and will be re assembling tomorrow. We have had to jig up and grind a little off the valve lifter mechanism on the...

www.r3owners.net

The Master Guru aka: Mr Albans talks about having to modify valve geometry after a Cam change increasing Lift and Duration.

This is why I suggested calling the Cam Maker and/or posting the cam profile/specs.