• Jimmy
  • Ripened Lemon
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  • From: Collegeville, Pa
  • Registered: 2019-06-19
  • Posts: 134

Topic: Moly or Cast piston rings ?

So we had a ball running the #77 Cordoba in NH. Everybody was super cool are very helpful. I really appreciate that.  Unfortunately we kinda blowed up the 400 big block. I am rebuilding a junk yard spare 400 to drop in. My question is the motor is in good condition and the bores are pretty good with little wear. I plan on doing a dingle ball hone job and re-ringing it. However should I use Moly rings which are better for abuse but might not be happy with my low tech cylinder prep, or use cast rings that have a better chance breaking in because they are softer?


I am leaning towards moly.....


When I was young I just slapped this stuff together and somehow it ran, now I am full of " analysis Paralysis"


Thanks!

Cordoba
  • From: Seacoast NH
  • Registered: 2013-01-01
  • Posts: 472

Re: Moly or Cast piston rings ?

Loved the car.  But I'm pretty sure that no matter what you put in for rings it'll blowed up again.  I can appreciate all of you who like wrestling with the car on race weekends but...  Been there got it and have the "we got screwed" trophy...  Hoping to never see that again

"We Got Screwed" NHMS 2017, 4th NHMS 2020,  4th NJMP 2021,
"Judges Choice" NHMS 2021,10th NJMP 2022, 3rd Thompson 2022
#847 Batmobile  aka-"Beulah"  search Squidrope Racing on Facebook
  • Mr.Yuck
  • Mr.Yuck
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  • From: Brookeville, Md.
  • Registered: 2013-12-09
  • Posts: 1,012

Re: Moly or Cast piston rings ?

Jimmy wrote:

So we had a ball running the #77 Cordoba in NH. Everybody was super cool are very helpful. I really appreciate that.  Unfortunately we kinda blowed up the 400 big block. I am rebuilding a junk yard spare 400 to drop in. My question is the motor is in good condition and the bores are pretty good with little wear. I plan on doing a dingle ball hone job and re-ringing it. However should I use Moly rings which are better for abuse but might not be happy with my low tech cylinder prep, or use cast rings that have a better chance breaking in because they are softer?


I am leaning towards moly.....


When I was young I just slapped this stuff together and somehow it ran, now I am full of " analysis Paralysis"


Thanks!

love the car, I'm a big mopar fan.  I don't think rings are going to be the problem, Make sure you get some decent rod bearings. If it were me I'd clean all the oil galleys, use a good oil pump, get a 1/2" pick up if you can, a good timing chain set, Summit cam K6400 (214/224-444/466), Clean the heads up and roll. If you can find a nice used DP4B intake that can help too. Try and keep it under 5500 and you should be fine. I have a friend with a HUGE amount of parts, if you need anything Message me. He might even have everything you need to rebuild the 400.

"get up and get your grandma outta here"
  • Jimmy
  • Ripened Lemon
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  • From: Collegeville, Pa
  • Registered: 2019-06-19
  • Posts: 134

Re: Moly or Cast piston rings ?

Where is your optimism Squrope?.......Blow up again?........Never!!!   I'll make this big girl last a full race one way or another. ( To be honest I didn't think it would make 50 laps let alone 140)

Well......I'll put all the bits and pieces back together and we will see what happens. Thanks for the good idea and advice. I need all the help I can get.!

Cordoba
  • Mr.Yuck
  • Mr.Yuck
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  • From: Brookeville, Md.
  • Registered: 2013-12-09
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Re: Moly or Cast piston rings ?

Jimmy wrote:

Where is your optimism Squrope?.......Blow up again?........Never!!!   I'll make this big girl last a full race one way or another. ( To be honest I didn't think it would make 50 laps let alone 140)

Well......I'll put all the bits and pieces back together and we will see what happens. Thanks for the good idea and advice. I need all the help I can get.!

if you do break this one try a 383 next time.

"get up and get your grandma outta here"
  • From: Orion Twp, MI
  • Registered: 2011-04-18
  • Posts: 776

Re: Moly or Cast piston rings ?

If I had to choose between cast or moly pistons for a Mopar 400, I would choose late model Magnum 5.9L.

As a former Mirada chief engineer / mechanic, the decision to drop the LA motor for a modern Magnum motor was a no-brainer. I went to my local junk yard with $300 in my hand and asked for the lowest mileage modern 360 they had on the shelf. The yard owner laughed at me, then asked how many I wanted for $300.

Seriously, Magnum truck motor. You won't be disappointed. They are uber cheap and make butt loads or torques.

If you INSIST on keeping the Gerald Ford approved Mopar 400, definitely moly rings after a dingle ball.

The Pentastar whisperer

Bayley's Website

  • Mr.Yuck
  • Mr.Yuck
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  • Registered: 2013-12-09
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Re: Moly or Cast piston rings ?

Bayley wrote:

If I had to choose between cast or moly pistons for a Mopar 400, I would choose late model Magnum 5.9L.

As a former Mirada chief engineer / mechanic, the decision to drop the LA motor for a modern Magnum motor was a no-brainer. I went to my local junk yard with $300 in my hand and asked for the lowest mileage modern 360 they had on the shelf. The yard owner laughed at me, then asked how many I wanted for $300.

Seriously, Magnum truck motor. You won't be disappointed. They are uber cheap and make butt loads or torques.

If you INSIST on keeping the Gerald Ford approved Mopar 400, definitely moly rings after a dingle ball.

only problem with that is he'll need a new trans and driveshaft, but yes both 5.2 and 5.9 Magnums run well. AND it would be some weight off the nose.

"get up and get your grandma outta here"