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ziff73

Piston orientation

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Very quick question. I'm assembling my engine and realized that the pistons aren't marked for front back orientation.. I think I have it figured out, but definitely don't want to put them in backwards..;-/...Does anyone here know, without a doubt, the right way? If not, no biggie, I'll wait till monday, but I'd love to build this thing this weekend!

photo-2.jpg

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Big valve relief under the intake, it's that easy.

You can also nestle them into the head, and the popup will tuck into the

dome only one way.

Odd surface finish- when I got forged pistons, my machinist, who knows

a bit about a bit, chamfered all the sharp edges to maybe a 1/16" radius.

I was a bit freaked, but both Jeff Ireland AND Ross said it's good practice-

it reduces hot spots and thus, detonation sensitivity.

But it's time- consuming, so they don't do it in manufacture.

t

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Thanks for the quick reply! I figured the same, but after fitting against the head with valves closed and alternating between intake and exhaust open, it only fits the other way. The upper portion of the picture only fits the exhaust side when open..plus the shape of the raised portion only really gets a good match with it positioned like that. Is that crazy? If it fits, it fits, right?

Would you be willing to chat on the phone for a sec?

Stephen

323 six eight seven nine five nine nine

Thanks!

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Here's the example of the piston with head..see how the shape fits if you imagine the green lines flipping to their respective positions? Seems obvious, right? So intake has small relief and exhaust has bigger relief...correct?

Actually, I think the relief cuts may be almost the same...it's where they are in the dome that makes them look different sizes...

photo-3.jpg

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Yep, your drawing is right, and I agree about the reliefs.

I WOULD seriously consider 'breaking' all the sharp edges a bit, even if

only with something like crocus cloth. VERY carefully, to avoid getting grit

anywhere but on the domes...

t

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Thanks for the info! I will indeed make that happen.

Unfortunately, I accidentally snapped a piece of the second compression ring on one piston when I was tapping it in...the edge popped out of the stupid ring compressor and I didn't see it...damn....now I can't finish until next week...very upset with myself..

Here's a pic of where I'm stuck at...three pistons in, oil pump and chain, timing chain and rails....I could've finished it this weekend!!! oh well..

photo-4.jpg

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I hate it when that happens.

or when you twist it just a little too much on installation, even though you know better...

t

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Yep...I'm all for learning lessons, but on a weekend when I can't get parts!!? Hehe... Oh well, it's not like the car is just waiting for the engine...still a decent list of stuff to do..

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wow, I think the last time my engine was that clean was when I bought the car off the showroom floor .....

Cheers,

Carl

p.s. Ziff, since you can't finish the engine, go have dinner at Lum Ka Naad on Reseda Blvd at Rayen ...... some awesome Thai will make the disappointment fade away ....

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Ooooo, I'll have to check that out! Thanks for the tip...

Yeah, I'm hoping to keep this car as my first ever 'no rain' car...in fact, I may never wash it, as it'll never get dirty enough...we'll see how long that lasts...;-)

Stephen

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