Author Topic: Petter AD1 piston clearance  (Read 5187 times)

millman56

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Petter AD1 piston clearance
« on: March 28, 2013, 11:41:07 PM »
Anyone know the nominal piston clearance for a Petter AD1 ?   

Mark.

buickanddeere

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Re: Petter AD1 piston clearance
« Reply #1 on: March 29, 2013, 04:17:14 PM »
Most engines that size. 30 to 40 thou cold. Best measured with a test Assembly with soft solder pieces set on top of the piston. Assemble, torque , rotate slowly a couple of times. Remove head and measure squished lead with a micrometer.
   Closer without hitting the head is better for starting, fuel efficiency and clean combustion. In wedge head spark ignition engines. Keeping the quench area clearance tight will reduce the tendency of detonation/knock. 

millman56

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Re: Petter AD1 piston clearance
« Reply #2 on: March 29, 2013, 07:07:08 PM »
Thanks for that Buickandeere,   I should have been a bit more specific, its the piston to bore clearance I need to know as my reboring guy will not have this info to hand.

Mark.

buickanddeere

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Re: Petter AD1 piston clearance
« Reply #3 on: March 30, 2013, 05:32:37 PM »
Rule of thumb is approx 1 thou clearance per inch of bore diameter. Cast tiron expands less than aluminum. New or mixure of used and new components? Is the engine a hobby toy or used and needs to be relied on ?

millman56

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Re: Petter AD1 piston clearance
« Reply #4 on: March 30, 2013, 07:25:56 PM »
Its 80mm or 3.125" bore  and cast iron.   The engine is a worker and its directly coupled to a 5 Kva generator.   The reason for repair is that the piston has 3/4"long  piece of the land between the top and second ring missing, I have a new +0.040" piston and rings for it.

Mark.

listard-jp2

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Re: Petter AD1 piston clearance
« Reply #5 on: March 30, 2013, 07:28:58 PM »
Just add the piston oversize to the STD bore size dimension. Does the oversize piston you have not come with the reboring dimension?

millman56

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Re: Petter AD1 piston clearance
« Reply #6 on: March 30, 2013, 08:09:21 PM »
The piston does not have any info whatsoever with it, in fact it was purchased as an AC1 piston.   The guy who is doing the rebore does classic motorcycle work so may not be au fait with diesel engine tolerances so I think 0.003" clearance as per Buickanddeeres advice will be the way forward.

Mark.