<VV> Bizzare piston slap memories

Hugo Miller hugo at aruncoaches.co.uk
Sat Nov 2 07:07:46 EDT 2019

True Redneck engineering! I knew a guy in England many years ago who 
rebuilt the crank on his single cylinder 1930's motorcycle on the side 
of the road (no idea why he had to do that!). He trued it up by rolling 
it along the kerb stone (we have proper cast concrete kerbs on the 
highways in England).
Another friend of mine (Nick Skeates - well known in the boating world 
these days) rebuilt his 1950 Sunbeam motorcycle and embarked on a tour 
of the USA. In the high altitude at Colorado, one of the exhaust valves 
started picking up in the guide. So he had the head off at the roadside, 
valves out, and eased the guides with a small round file (a "rat's tail" 
file) and contnued his adventure.
Ah, the good old days! You had to learn how to be resourceful back 

On 2019-11-02 08:28, Jay Maechtlen via VirtualVairs wrote:
> Over the years, a couple of motors I've overhauled have had piston 
> slap.
> These were quick 'rings & inserts' jobs, with my un-patented back
> yard valve jobs.
> (Support a valve in a piece of tubing, let the face spin at an angle
> to the side of a fine grit bench grinder, adjust angle to regulate
> spin rate. Cleans them up ok. Then lap the fresh valve onto the seat,
> cleans the seat and knocks the grinding marks off the valve face)
> The motors would chuckle or 'talk' a bit at idle, but they ran fine.
> One was a 383 Merc (MEL motor) and one was the Ford 240 cid six.
> Of course, the 'slap' from a piston .020 or .030 too small would
> probably be pretty awful, and might not quiet down much under load...
> On 11/1/2019 5:17 PM, N2VZD TIM via VirtualVairs wrote:
>> I had a crazy issue a few years ago with brand new pistons . They 
>> were supposed to be .060 (factory marked !) but were actually .030 
>> measured . This was after going nuts with the sounds. The compression 
>> was "OK" but the noise was almost like lifter noise or oil pressure 
>> problem , but gauge showed good pressure. I will never buy parts like 
>> that from anywhere but my trusted source. These were new parts in the 
>> boxes from a private vendor at the Sturbridge .He probably had no idea 
>> , because they were NOS not  properly marked in correct boxes  (they 
>> said .060 on top but measured .030 at the shop.   Very strange noise!  
>> I never had to check measurements before !Regards, Tim Colson
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