Problems with valve lifter - wrong rocker arm perhaps?

[stevewhitt]

Hi All

I received my new valve lifter assembly, and set to fitting it today, following all the instructions on the forum. However, once the body is screwed into place, the cam cannot be rotated clockwise so that it is above the rocker. It is fouling. If I back the assembly off, I can get the cam above the rocker arm, but when I start to tighten the assembly, it binds up and starts to depress the valve.
I have attached a close up picture.
I could grind part of the cam back, but I don't think that is a good idea.
I suspect something else is not assembled correctly, or is the wrong part.
I did set the valve timing.

Any ideas/suggestions?

[will_curry]

Steve,

That rocker arm looks rather high to me. I'd expect to see more
thread on the adjuster. I'd suspect a pushrod rather shorter than
usual rather than the rocker arm itself. I think there was only ever one
rocker arm for the enclosed valve heads.

[volker.halbach]

Hi Steve,

Which cam do you have? If you have replaced your original F cam with a newer cam with smaller diameter, e.g., the standard single-lobe cam, and keep the original pushrods, then the tappet adjusters may just be long enough to adjust the valve clearance correctly and then it looks like this.

[stevewhitt]

I don't know as I have not had this engine apart. I think Will's explanation sounds correct. Ill extract the pushrod and measure it. I think I need part 1856-34?

[volker.halbach]

It's more likely the cam. If you combine the later pushrods with the early cam (as would have been originally in your WNG), the pushrod appears to be too long. What you have looks like the later cam with the earlier (shorter) pushrods. Of course, some previous owner could have shortened the pushrods or done something else to the valve train.

[stevewhitt]

When you say 'cam' Volker, are you referring to the cam on the valve lifter or the cam on the exhaust rocker?

[stevewhitt]

If as you say I have the earlier (shorter) pushrods, do you know the part number for the longer version please?

[stevewhitt]

Thanks for all the input so far. I have taken the rocker arm and pushrod out. The pushrod is very close to 10-3/8", so to spec. There is no way the cam on the valve lifter will clear the rocker arm, irrespective of what pushrod is fitted. So I can only conclude the rocker arm is not the correct one. If someone could conform based on attached photo's before I start looking for a replacement that would be very helpful.

Regards

Steve

[volker.halbach]

Steve, by "cam" I meant the camshaft in the bottom end. They are often replaced either because parts are worn out or because owners want more power. Later camshafts have a smaller diameter and need then longer pushrods. Sorry, I don't know the part number, but it should be easy to find out from the Draganfly web site. I might even have a pair of the longer pushrods.

[stevewhitt]

Yes, I understand now, thanks Volker. Draganfly have 1 in stock which is 10-11/16 which I shall buy and try. They also list, but do not have in stock a 10 -5/8" which I think may be the one I need. Its trial and error!