Centerline distance between buckets and valves

[Bedifferent]

If you have your valve cover off or a spare head laying around, do you know what the centerline distance is between the shim buckets on the rocket. I assume it would be the same as the centerline distance of the valve stems.

Just gathering some info for the shim tool. After getting some feedback from Paul using my tool, I'm looking to see if I can get a better finger fit around the radius edge of the shim bucket. The finger might require a little twist and it would help if I can make a little mockup of what I'm looking at.

 

[Joesmoe]

@warp9.9 @Neville Lush @Speedy @Rocket Scientist @Claviger @R-III-R Turbo @cootertwo

 

[warp9.9]

Sky's are opening up right now. But I'll see if I can come up with a figure later after it lets up.

 

[Claviger]

Mines all buttoned up at the moment, but, I’d be shocked if there’s any difference between valve and bucket centerline.

 

[R-III-R Turbo]

Not sure if the info i have can be used here, assumptions would have to be made, but the paired cam lobe distance from centre to centre is about 43mm

Cam measurements 1

• R-III-R Turbo
• Oct 5, 2018

Cam measurements 1

Cam measurements 2

• R-III-R Turbo
• Oct 5, 2018

Cam measurements 2

 

[Bedifferent]

Not sure if the info i have can be used here, assumptions would have to be made, but the paired cam lobe distance from centre to centre is about 43mm

Cam measurements 1

• R-III-R Turbo
• Oct 5, 2018

Cam measurements 1

Cam measurements 2

• R-III-R Turbo
• Oct 5, 2018

Cam measurements 2

Good pictures! It looks like the cam lobes aren't centered on the valves. Is that an optical illusion? If I took one cam lobe width (assuming they are the same) and subtracted it from the total width across the number would it still be off a bit. It does appear to be around 43 mm or 1.69 inches. Since they appear a little wider than that, the centerline distance should be a little wider than that 1 1/2" number which is the centerline finger distance on the shim tools that have been posted. That would explain why the inside edges of the finger didn't rest fully on the bucket when Paul tried the tool I made. I think a little twist on the ends will fix that but I need to make mock up. Just trying to get it as close as possible.

 

[warp9.9]

If you have your valve cover off or a spare head laying around, do you know what the centerline distance is between the shim buckets on the rocket. I assume it would be the same as the centerline distance of the valve stems.

Just gathering some info for the shim tool. After getting some feedback from Paul using my tool, I'm looking to see if I can get a better finger fit around the radius edge of the shim bucket. The finger might require a little twist and it would help if I can make a little mockup of what I'm looking at.

Center to Center of the buckets = 1.655"
Thats measuring the bucket hole centerline.

 

[Speedy]

Flat tappet cam lobes are always offset from the bucket centerline. This rotates the bucket (tappet) as it opens so that wear from the cam lobe rubbing on the bucket is spread across the entire bucket face. The buckets are not flat either. They have a crown (convex) and the lobes are ground at an angle. All to keep the bucket and valve rotating to distribute wear uniformly.

Cam followers with a radius, like those used in old Triumphs can't rotate so the above doesn't apply. These function with a geometry similar to that of roller lifters.

 

[Bedifferent]

Center to Center = 1.655"

Thanks...Now I can go to work!

 

[Bedifferent]

Flat tappet cam lobes are always offset from the bucket centerline. This rotates the bucket (tappet) as it opens so that wear from the cam lobe rubbing on the bucket is spread across the entire bucket face. The buckets are not flat either. They have a crown (convex) and the lobes are ground at an angle. All to keep the bucket and valve rotating to distribute wear uniformly.

Cam followers with a radius, like those used in old Triumphs can't rotate so the above doesn't apply. These function with a geometry similar to that of roller lifters.

That makes sense...more knowledge...I forgot about the rotation.