Pics as promised , drove it for 20 mins and she drive like a dream , very responsive no pops or bangs
Those adjusting screws have a pronounced ball end and the small contact area is probably hammering into the valve stem. These would be better. EDIT: Where did you buy the new adjusters?
Some i used before I converted to elephants foot type were made of cheese I recon. There’s a lot of poor quality repo out there. I think Heritage did some better quality ones but do some searching.
Why were the screws changed? You said that after that driveway idling and revving to check/set the timing the gaps had changed to 1.5mm+. Then you reset and went for a drive without problem. I suggest if it something wearing they would have increased again similarly dramatically. Have you checked them after your drive? I don't mean to be rude but is it possible your valve gap setting is a wee bit... suspect? Rockers can be strange beasts - I always grab the valve end and give them a good heave-ho in and out rattling after setting each one, then double check the gap.
They were replaced when I changed the exhaust valves in the heads just so every thing was new, On the original build, I did the 20mins @ 2000rpm , then did a 140 mile break in "trip" just local roads ran fine Next morning, checked clearances and they had increased to .80+( didn't bother measuring exactly just put the .80 feeler in and it was more than that,) adjusted to 0.15 left overnight went to go camping and it blew up after 40 miles On this occasion I rebuilt every thing again, checked checked and checked, let it idle so I can be sure it would run when on the road checked timing, it ran for less than 10 mins , it was getting late so xalled it a day, Checked the clearances this morning and they had increased to the measurements in the picture, Rocker shaft nuts tights, Push rods @280mm Reset to 0.15 Drove for 20 mins and will check again in the morning I always push the rocker on to the pushrod when checking/adjusting, 1 exhaust and 1 inlet will rock on that cylinder, inlet on the Next cylinder will also rock ,
A comment about idling the engine - don’t. The valve train from cam right through to valve tip is under the same load at idle as it is at 5000 revs BUT it has little lubrication at low revs. People that start the engine and allow it to idle to warm up are damaging the engine unnecessarily; clearances throughout the engine are designed for normal operating temperature and it should reach that temperature as soon as possible. The engine will never reach normal temperature idling.
I understand the dont let it idle, but how are you meant to make sure it's going to actually run, so It don't cut out when you press the throttle, carb adjustments are done, and timing set, all needs to be adjusted before you can drive it, I understand the metal on metal wear untill the engine has lubricated it's self
Ok, so after resetting the clearances to .15 yesterday and taking it for a 20 min drive I've just rechecked the clearances on a stone cold engine Please see pic , only one slight adjustment made I will be checking after every use for the next week or so to monitor
Excellent - what do you think then - user error or wibbly engine? There would be no "settling in" here so you can't hope that was the cause of the initial huge increase in the gaps. Anyway, fingers crossed you now have it set right and will have many years trouble free motoring.
I Honestly don't know, it seems strange I did every thing exactly the same , set all the clearances whilst on the engine stand after torquing up the heads and barrels, I've just returned from Harry harpic, he checked all the timing, dwel angle, max advance, the only adjustment he made was with the fuel screw on the ict carbs, I took the destroyed piston and he thinks air leak to cause that damage I'm going to check clearance again tomorrow when cold, and fingers crossed all ok
Do you have empi fibre gaskets between head and inlet manifolds? I really like them, but after the first 10-20 miles they always need retightening. Not a bad idea to check inlet and exhaust fixings after that kind of initial mileage anyway. After that things tend to stay put.
No just No just the pressed metal ones, I will be checking all nuts tomorrow, I've just found the dipstick temperature vague that I will also fit
Do you remember any problem regarding the inlet manifolds and the cylinder shroud tinware? Perhaps last time they clashed leaving a leak, it's a very common problem.
I did, it was on a replacement 1&2 cover, which I had to rivet the air deflector on the back as it never had one, I persuaded it with a bit of wood to clearance the manifolds only on 1&2 , 3&4 was fine, I think the tinware was repro,
