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Jul 10, 2011 19:26:03 GMT
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I took the head off my 2l inj pinto engine today (205 block) and after cleaning up the piston CROWNs i could see some numbers. What do they mean? Theres a number '3' with an arrow:  Them there's some smaller numbers:  Any ideas? |
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Dez
Club Retro Rides Member
And I won't sit down. And I won't shut up. And most of all I will not grow up.
Posts: 11,790
Club RR Member Number: 34
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Numbers on pinto pistons?Dez
@dez
Club Retro Rides Member 34
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Jul 10, 2011 22:23:54 GMT
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the larger number- I'm not sure, but id assume the pistons are numbered if they're matchweighted with the con-rods. theyd usually be scratched in by an engine builder rather than factory stamped though. the arrow usually points towards the flywheel. so you get the piston abcin the same way round after replacing rings.
the smaller numbers are just factory production codes/model numbers afaik. the big M means they're made by mahle.
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bortaf
Posted a lot
Posts: 4,549
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Jul 10, 2011 22:34:58 GMT
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Arrow IIRC ? points to the front of the engine and the number is a grade used during the initial build, either weight of the bore grade, no real idea what the others are, on aftermarket pistons they are the size ?
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Last Edit: Jul 10, 2011 22:38:42 GMT by bortaf
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Jul 10, 2011 23:19:41 GMT
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they look aftermarket IMO
i thought the arrow pointed to the front too
tried googling the small numbers?
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Someone just shot the elephant in the room. |
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RobinJI
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"Driven by the irony that only being shackled to the road could ever I be free"
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Just had a look at a piston next to me, which I know to be made by Mahle aswell (Out of a 1.8 20vt VW engine), it has the same M stamp, also with small numbers above and bellow it in the same format, an arrow pointing towards the front (cam-belt end) of the engine, the diameter and '1' stamped into it, and it happens to be from cylinder 1, I'm fairly sure that's no coincidence.
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Last Edit: Jul 11, 2011 2:03:51 GMT by RobinJI
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bortaf
Posted a lot
Posts: 4,549
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Jul 11, 2011 13:02:16 GMT
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Just had a look at a piston next to me, which I know to be made by Mahle aswell (Out of a 1.8 20vt VW engine), it has the same M stamp, also with small numbers above and bellow it in the same format, an arrow pointing towards the front (cam-belt end) of the engine, the diameter and '1' stamped into it, and it happens to be from cylinder 1, I'm fairly sure that's no coincidence. It is on a pinto, my EFi has 3 3's and a 2, we're talking about shoddy ford build quality here not metromomic VW efficiency  when cosworth "selected" the EFi blocks for the early cosworth 16v turbo they selected blocks where all the numbers on the pistons were 2 or 3 which is in the middle of the casting tolerence, 1s and 4s were left for us normal peeps to use. |
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R.I.P photobucket
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RobinJI
Posted a lot
"Driven by the irony that only being shackled to the road could ever I be free"
Posts: 2,995
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Jul 11, 2011 13:58:50 GMT
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Ah, yeah, it could well be a coincidence. The only thing that makes me think it isn't is that I've gone over it with black marker, and I remember marking each cylinder assembly as I dismantled the engine. If it had been a random un-related marking I'd have expected my self to write the 1 somewhere else, rather than going over the factory stamp. It was a year or so ago though. Plus like you say, they're different manufacturers.
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Last Edit: Jul 11, 2011 13:59:30 GMT by RobinJI
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Jul 11, 2011 15:23:56 GMT
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I've got some Mahle pistons (Dolly Sprint) with the same M stamping on the top too, with the arrow, but the grading system on them is a letter (F on these)
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bortaf
Posted a lot
Posts: 4,549
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Jul 11, 2011 21:05:00 GMT
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Ah, yeah, it could well be a coincidence. The only thing that makes me think it isn't is that I've gone over it with black marker, and I remember marking each cylinder assembly as I dismantled the engine. If it had been a random un-related marking I'd have expected my self to write the 1 somewhere else, rather than going over the factory stamp. It was a year or so ago though. Plus like you say, they're different manufacturers. It could well meen that on a VW  i was serious when i said shoddy ford Vs way better VW build quality ;D even though the build quality on the later blocks was better than the early they are still shoddy in comparison to some other manufacturers |
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R.I.P photobucket
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Jul 13, 2011 16:56:42 GMT
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mine are all number 3's so that's a good sign then!!
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