Hitchcocks Forum

Hello brains trust, I am at present at the reassembly stage of my 1948 (?) Model G project. It came in a state and is now a collection of resurrected, new and restored parts. I have never seen a Model G complete and running, ever, so there is a surprise in store, one would hope, when it does. Current headache is the valve lifter. First surprise was the exhaust valve was installed in the inlet valve position and vice versa, no valve lifter on the bike when I got it and a plug in the barrel where the lifter cable goes in. Changed this and adjusted both to spec's and installed valve lifter. Does not seem to have a great degree of travel and does not at any stage connect with the stop on the pushrod. I cannot see any spacer for the lifter to keep it proud of the stop cast into the barrel which seems to be deliberately designed to be there. I gather that not too much lifting would be require for there to be decompression but the lack of marriage between lifter and pushrod has me flummoxed. The bike is a mish-mash of parts anyway, mostly RE but a liberal amount of Triumph, and even AJS (I think) for the number plate/tail light holder, so wont be surprised to find the wrong valve or pushrod. More than likely ignorance on my part as to the correct installation of the lifter. I have managed to deduct that it is not the valve seated to low in the head as this would have the effect of lowering the stop toward where the lifter is at present. Any ideas? is it possible to adjust the pushrod to ensure the stop and lifter line up? Any help greatly appreciated.Cheers
Tad Haggard
PS I live remote

https://ibb.co/jHM55S

Hi Ted. Just looked at my engine, which is part dimantled. There seems to be a small amount of movement between the valve lifter lifting the pushrod and coming up against the cast in stop, just a few mm.

kind REgards

Dave

Thanks for the reply Dave, and doubly so for the photo. I clearly have a problem. I will endeavour to load some photos of the top and bottom of the pushrods. I am coming to the conclusion I have come across another bush mechanic hack employed by a PO to get it going. I did check and found the pushrods to be equal in length as were the valve stems, as best I could tell (didn’t actually measure the pushrods however). Rocker arm (exhaust) is sitting much higher (approx 1/4 “) than the inlet with correct adjustment on pushrod side, valve side they are equal. Photos will show this, I will have to learn the knack of incorporating them. Is it possible the rocker is bent? I can’t see how, there is no distortion or cracking as is to be expected with physical damage. Unfortunately they are a mirror image of each other so I can’t just swap them around to see if that is the problem. Maybe the exhaust valve stem should be longer than the inlet valve stem. Or maybe, and I suspect more likely, the rocker arm on the exhaust side is from a different model, all other things bein equal.
Cheers
Tad

Tad, (whatever your name is!) looking at the 48 Parts Book I notice that the tappets and guides (within the tappet chest in the crankcase) are different lengths. Could these have been installed the wrong way round or mixed up?

REgards, Mark

Hi Guys---------Hi Mark, yes I agree--- the longer Tappet and the longer guide are fitted in the front and operate the exhaust push-rod...thus both valve pushrods are of equal length ( Unlike the Iron 350 / 500 engines )..BUT the exhaust one has that flange on the bottom...Is our friend "Tad" related to Henry Rider by any chance ??

Hi Tad,Have you ensured that the valve stem lash caps are installed. When ommitted they cause the rocker arm to sit more into the valve thus more adjustment is required from the pushrod adjuster. It also gives the impression that the rocker arm is bent (as you have described). Part number 10672 is the lash cap (or valve stem cap). Regards.

http://s1262.photobucket.com/user/tadha ... sort=3&o=0
http://s1262.photobucket.com/user/tadha ... sort=3&o=1
Hopefully this will give pictures to look at. Note Rocker for exhaust valve is noticeably higher than the rocker for the inlet, the other side (valves) are equal, the pushrod is adjusted up to accommodate the rocker which has pushed the stop out of reach of the valve lifter, I had a look at the tappets but if they were reversed or the wrong size there would be difficulty fitting one pushrod (Inlet) and the other tappet would not protrude from the crankcase (exhaust), this is not the situation here but I must commend the deduction. The parts book does not indicate in any way that the valves are a different length though they are different part numbers. All I can come up with now is that I have either the wrong pushrod, rocker or exhaust valve, or any combination of some or all of them. Next time I get to this I will measure and photograph everything.
Cheers and Thanks for your help
Tad
(my country music stage name, also how I feel most of the time, "a tad haggard")

http://s1262.photobucket.com/user/tadha ... sort=3&o=1
http://s1262.photobucket.com/user/tadha ... sort=3&o=1
Try this