Can anyone tell me the compression ratio and model numbers for pistons 65661?

[pistoncan]

I was wondering if anyone can tell me what engine models use lycoming 65661 pistons and what the compression ratio was for them Thanks

Gary

[pistoncan]

I am guessing that they are low compression pistons for the O290 or the O435 but it is just a guess.

[Jim]

Hi,

Good guess!

https://www.google.com/search?as_q=6...pe=&as_rights=

[pistoncan]

there is a guy on ebay selling new old stock (from 1949) pistons in cosmoline for 20 bucks each. I figured somebody on here with an O290-D might be able to use them. To my uninformed senses they seem like a bargin. Looks like 4 ring pistons.

http://www.ebay.com/itm/262275998443...%3AMEBIDX%3AIT

[Steve Pierce]

There is a thread on different engine models which has a PDF document with all the Lycoming models and their compression ratios.

[pistoncan]

There is a thread on different engine models which has a PDF document with all the Lycoming models and their compression ratios.

I've been looking but I haven't found it yet.

From the parts manual I have

69958 6.5 compression D engine
69841 7.5 compression D2 engine
70396 7.0 compression D2B and D2C engine

No 65661 I wonder if they might be O290G pistons? or 435 pistons

[Steve Pierce]

http://www.shortwingpipers.org/forum...3007#post93007

The Type Certificate Data Sheets have the compression ratios and lots of otherdata as well.