Push rod rattle ?

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Torontonian

Torontonian

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Norton 850 1976. 40 oversize new pistons.Changed out head from RH 4 Large 32 intake ports to RH 10 smaller , 30 mm. New Black diamond valves fitted with Kibblewhite seals and stock new composite 850 gasket. Stock crossover exhaust ,new. D.T. headsteady. Raised up Interstate tank with rubbers to see if it could be tapping tank but a no. The hard part was listening for source of intermittent rattlin's as did not want to burn face on hot exhaust. It's coming from Push rods tunnels front. Rattles most when letting out clutch in first. But could rattle anytime. Sweet spot around 3000 RPM. seems better. Pulled valve covers this morning and all was good , 006 inlet clearance and 008 exhaust. All rockers in cups good with flashlight. Runs perfect . I'm leaving in the morning up Hockley valley to an experimental music festival for 4 days. Like I said runs perfect.
 
Did you change your cam followers at all?
 
Torontonian said:
No. Looked fine and std. Cam. I am thinking either head casting flash or maybe head gasket protruding into tunnels. New Boyer MK 1V.
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You definitely have the ball of all four rockers located in the push rods?
 
"Could it be detonation i'm hearing ?"

It could be, and if so you might find the motor is easy to stall, there's a ringing noise when pulling and the exhaust loud.
Here's a long shot; check the front ISO gap isn't too big as it could be the cups rattling.
Dave
 
I haven't done an extensive study on internet reported noise issues and successful fixes from online replies (especially with no accompanying sound clip or video), but my wild guess would be 50% at BEST, even with extensive detailed back-and forth, PRIOR to actual dismantling and proper troubleshooting.

"just saying"
 
cash said:
"Could it be detonation i'm hearing ?"

It could be, and if so you might find the motor is easy to stall, there's a ringing noise when pulling and the exhaust loud.
Here's a long shot; check the front ISO gap isn't too big as it could be the cups rattling.
Dave
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Yes I will check this , good idea. Heading up north now on it for 4 days . Electriceclectics.ca .
 
cash said:
Here's a long shot; check the front ISO gap isn't too big as it could be the cups rattling.
Dave
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Maybe not a long shot - since 3000 rpm he says is the "sweet spot". Seems more plausible than valve train noise, which wouldn't come and go.
 
Loose socket left on one of the recessed head bolts up front? That will do it!
 
Did you check to make sure the 3 o-rings are in place under the headlight shell brackets. If these have deteriorated or missing there will be a buzz at certain RPM ranges. If you grab the bracket and lift it up and down and you hear a mechanical clunk , that might be where your rattle is coming from.
Tom
 
Use a solid metal rod or stethoscope to get in there and listen closely (touch other end to areas of the engine you suspect of the rattle). That will help you find the sound's point of origin.
 
Jdub said:
Use a solid metal rod or stethoscope to get in there and listen closely (touch other end to areas of the engine you suspect of the rattle). That will help you find the sound's point of origin.
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Das Boot style.
 
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