Pushrod problems

Putting my 74 850 back together. It was missing the head and I was able to locate another one. I had a grab bag full of pushrods, so I pulled out 4 with no damage and checked on a glass plate for straightness. Got the head on and snugged down on the cylinder block but not torqued. Decided to spin the engine to check for valve operation and to preliminarily set clearances. The right side exhaust had no clearance with the adjuster backed all the way out and the left valve at max lift. Took the head off and could find no problems. Put the head back on and same problem. All the other valves I could set clearance on but not the right exhaust valve. Pulled the head again and started to scrutize all the components. Found one exhaust pushrod measured 189 mm or 3mm longer than the other one. The other matches the spec in the shop manual of 186 mm. I thought all Commando pushrods were the same.

htown16 said:

Found one exhaust pushrod measured 189 mm or 3mm longer than the other one. The other matches the spec in the shop manual of 186 mm. I thought all Commando pushrods were the same.

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http://www.rgmnorton.co.uk/shop/push-ro ... =20&dord=1

MODELS 77, 99, 650/99, 750 ATLAS PRIOR TO ENGINE NUMBER 125871. EXHAUST.

NOMINAL LENGTH: 7.416" (188MM)

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Shouldn't be much hassle to remove one of the cups and shorten the pushrod a bit. Racers used to have to do it all the time on cut-down motors.

Danno said:

Shouldn't be much hassle to remove one of the cups and shorten the pushrod a bit. Racers used to have to do it all the time on cut-down motors.

Click to expand...

Htown
maybe NOT ruin an atlas/650 pushrod (short vavlve stem) and grab a different/correct one from the grab bag. You never know when you need a long one...wish I had 2 like that right now...for my 650 :roll:

On closer inspections the intakes don't match either. Length is real close but barrel is different shape. Since I've got more than a few bucks in this engine so far I decided to not screw around and ordered these. Price is actually cheaper than Andover replacements.
http://www.ebay.com/itm/400889278679?_t ... EBIDX%3AIT
Dyno,
I've only got one of the longer exhaust pushrods for the short valves. If you want it you can have it.
Htown

I have a set of these Kibblewhites that will be going into my build. They are quite light at 23 g ex and 25 g in. The AN items are , according to Phil, solid and weigh about 45 g.

Ed

The kibblewhites look nice. It would be great if they made all the lengths with that particular column with those ball/socket ends. The point being that I am in the midst of a 4 engine evaluation. !953 M7, 1957 99std, and a 59 88std conversion , and a 650C?. I am always in the planning stage. Have they determined the resonant oscillation frequency of them. Can I buy it or do I have to make it? :x

I have a set of these Kibblewhite pushrods in my 850 interstate. Working good so far. What I pulled out before the rebuild was quite an eye opener. :shock: I could definitely see one stock pushrod was longer than the rest at the adjustment of the tappets.

Cheers,
Thomas
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