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Discussion Starter #1
I plan to purchase pistons/liners soon.
Do you recommend staying with the standard 84mm jetronic set or upgrading to the Motronic set?
Is there a significant performance power difference or is it marginal? Any thoughts welcome.
 

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I agree about piston rings. I had high oil consumption with the rings that came with the Motronic pistons and I eventually replaced them with Hastings which were much better.
 

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There is some speculation about the Hastings top chrome compression ring being brittle and prone to breakage. You can use the Hastings oil control ring ( the most important) and middle compression ring but the top ring can be replaced with the stock Motronic cast ring. I found documentation on this but the engine I performed this on has yet to be installed.
 

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Last that I heard, the stock pistons were no longer available new, forcing you to use Motronic? At any rate, my builder refused to use Hastings and wanted to use what came with the piston kit. Not sure of his source. Compression is down from new in 2018, just a tad (10psi or so) but so far my only oil issue is when the engine is hot; oil moves past the seals and comes out of the exhaust. Some head rebuild that was...
 

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There is some speculation about the Hastings top chrome compression ring being brittle and prone to breakage. You can use the Hastings oil control ring ( the most important) and middle compression ring but the top ring can be replaced with the stock Motronic cast ring. I found documentation on this but the engine I performed this on has yet to be installed.
Hastings make two different top rings and you get to choose if you order direct. They have an excellent advice desk. The cast iron ring has a barrel cross section and is usually recommended for road use. The chrome ring is rectangular and can withstand higher temperatures - a better choice for hot motors.
 

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Not sure where you're located. I recently rebuilt my '84 here in CA, and Stewart at APC recommended against Motronic pistons due to pinging concerns with our gasoline.

David O'D
Laguna CA
 

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Hastings make two different top rings and you get to choose if you order direct. They have an excellent advice desk. The cast iron ring has a barrel cross section and is usually recommended for road use. The chrome ring is rectangular and can withstand higher temperatures - a better choice for hot motors.
Ahhhhhh, I wondered what that issue was... mine will be a daily driver and could only do limited modifications due to CA smog laws. Pretty sure I made the right decision. I wonder why the scuttlebutt about the chrome rings breaking?
 

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Discussion Starter #10 (Edited)
Thanks for all the comments!
I decided to stick with standard jetronic liners after reading post of problems with the motronic upgrade. My original pistons are in Great condition. I will be installing Hastings rings. All engine rebuilding is being done with engine in car. Feels good to keep it as original as possible!
 
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