Mohavvalley

Looking at some options for the 525SC rebuild and could use some feedback on doing a 6.358" rod with a 1.365 tall piston (Ross 82016) with the bottom oil ring land partially exposed to the pin area. VS. going with a 6.135" rod and a 1.614" tall piston (Ross 83068)? Both on standard 4" stroke with either EQ 320 heads or Brodix DS320 heads (2.25/1.88 valve set ups).


I've read these threads but no real answer to this specific question:
Rod ratio vs reversion
540 stroker,,DUD engine, dont do it.


Rod info at 4.0 stroke is:



How will one VS the other work for power/Tq curve VS. engine longevity?

Young Performance

Have the blocks been decked a bunch? If not, your numbers are off. A stock length rod (6.135) would use a 1.645 Comp height piston and a +.250 rod (6.385) would use a 1.395 piston. These would leave the piston .020 in the hole is the block is a true 9.800". Your numbers would have the piston about .050 in the hole. You can go either way. It really won't make a difference. I would go with the 6.385 rod if you ever have any chance of changing the crank. A lot of aftermarket 4" cranks are being set up for a 6.385 rod as well as any 4.25" stroke crank would require at least that.
Eddie

Mohavvalley

No they have not, but I'm trying to put something together with a true off the shelf blower piston (.4 1st ring land) that isn't $1K for a set of pistons. I can deck the block so it's closer to .030 below but I assume it's better to leave as much block as possible for future changes? And from what I've read it's best to try and Zero the piston/deck height with your set up?

Going 6.385" will this require any set up or machining changes to make it reliable?


Thanks Eddie

AllDodge

iTrader: (1)

delete, sorry wrong forum and thread

MILD THUNDER

iTrader: (3)

I dont know why Ross makes that piston with a 1.365 CH when everyone else in the industry makes that combo's piston in a 1.395 CH (JE, Diamond, Icon, Wiseco etc). I definitely wouldnt mill .050-.070 though off the block to get to "0" deck with that piston.

I know that Ross piston has the ring .400 down, but I would not consider that makes it a "true blower piston" because of it. .300 down is plenty. I noticed that piston has 5/64 rings with a 3/16 oil ring. Most others are 1/16 rings with a 3/16 oil ring, some even going thinner than that with todays ring materials. Not sure if there's any benefit from those thick old school rings, maybe Eddie will chime in on that.

One of the other things you may consider when purchasing a piston, is the piston pins. Most pistons come with a standard 5115 low carbon steel .150 wall pin. I have the upgraded JE series 52 pins in my engines, per the machine shop . The standard pins are the series 51 for JE. Was it needed, I dont know. Probably not. I have seen the results of a failed wrist pin a long time ago on a buddys drag car, and it gets ugly.

phragle

iTrader: (3)

Its a 525sc, merc built a lot of them, people put a lot of hours on them, some even hopped them up a bit and still put a ton of hours on them. The only real negative you hear about them is that they can be thirsty.. Dont reinvent the wheel.Dont give yourself headaches. You are not going to be pushing a lot of boost with a 177 on a 454. If you think you are going to,, your in for a world of hurt,

Mohavvalley

Ok so looking at mid-range & budget rods for this build and I think it's down to H Beams by Eagle, Scat, Molnar, Lunati, & Manley ( unless you have other suggestions). All are less than $650 for the set with ARP 2000's So..... who's the best of the bunch (and why would be great).


Thanks

MILD THUNDER

iTrader: (3)

Molnar.

Call Tom . His products are very good, he backs them, and answers the phone.

Young Performance

Up to around 700 hp or so, I've used the Scat's for years with no complaints. Great rod for the money.
Eddie