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Rb30 Rods - Height Make A Difference

D1AUS

By D1AUS,
in Engines & Forced Induction

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D1AUS Rookie

D1AUS

Posted
Posted

Hey Guys

In the stages or tearing my engine down, ready for a rebuild.

There are a few retailes of RB30 Rods at the moment

- SPOOL

- ARGO

- Rod Factory

But whats got me confused is

Centre to Centre: some have 152.5mm and some have 155.5mm

Will either of the 2 work?

Anyone else come across this and what have you done

JD

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D1AUS Rookie

D1AUS

Posted
  • Author
Posted (edited)

Brad I spoke to you this morning about that, thanks for your help

Rods Factory, i know they are on ebay are 155.5mm

RacingPartsfactory.com also have them as 155.5mm

Will using the 155.5mm Rods pose a problem? I know they are 3mm longer, i am planning on using CP 8.2 Flat top Pistons with them

Edited by D1AUS
Spoolup Mentor

Spoolup

Posted
Posted

Umm yes - the pistom will protrude 3mm out of the bore and you wont be able to bolt the head on.

It just wont work - you will need to get a custom piston made to suit.

Brad I spoke to you this morning about that, thanks for your help

Rods Factory, i know they are on ebay are 155.5mm

RacingPartsfactory.com also have them as 155.5mm

Will using the 155.5mm Rods pose a problem? I know they are 3mm longer, i am planning on using CP 8.2 Flat top Pistons with them

D1AUS Rookie

D1AUS

Posted
  • Author
Posted (edited)

But from my calculations, it is ok.

RB30 Specs

RB30 Deck Height - 9.075" (230.5mm)

Stroke - 85mm

Crank Throw - 42.5mm

Compression Height - 1.280" (32.5mm)

Using Spool/Argo Rods - 152.5 C/C

Deck Clearance = 230.5 - 42.5 - 152.5 - 32.5 = 3mm

Using RacingPartsFactory/Rod Factory Rods - 155.5 C/C

Deck Clearance = 230.5 - 42.5 - 155.5 - 32.5 = 0mm

Is that right by your calculations, therefore using either Rod, should not matter.

However, if you see an issue of deck clearance, you can always use RB25/26 pistons instead, as they have the same bore, but a smalled Compression Height

post-43743-1193213677_thumb.jpg

Edited by D1AUS
D1AUS Rookie

D1AUS

Posted
  • Author
Posted

So that calculation above is wrong then??????????????????????

RB30 Compression Height - 1.280" (32.5mm)

RB26 Compression Height - 1.193" (30.3mm)

RB25 Compresson Height - 1.240" (31.5mm)

Using 152.5mm will yield 3mm Deck Clearance via that calculation

Using 155.5mm will yield 0mm Deck Clearnace via that calculation

Now thats even more confusing

D1AUS Rookie

D1AUS

Posted
  • Author
Posted

Why not just use the Argo or Spool rods and be done with it? They both work without any issues?

Its not just a matter of simply using any rod. I'm trying to maximise the compression ratio etc with my setup. And with the calculations above and speaking to Distributor for CP in QLD.

Standard Rods have a 3mm deck height according to this calculation. As the CP RB30 Pistons are Dished not domed. Thats my arguement here.

Just trying to find out from others who have done this etc.

I understand Spool Rods are of good quality, but just seeing the available options to maximise the setup, thats all.

JD

superjet760 Rising Star

superjet760

Posted
Posted

Im building a 30/26 now with 9:1 comp using argo rods 152.4mm center to center

also using je custom piston compression ,height of 1.283,

0 deck height

havnt got the pistons yet but thats what i did to get the comp i want

D1AUS Rookie

D1AUS

Posted
  • Author
Posted
Im building a 30/26 now with 9:1 comp using argo rods 152.4mm center to center

also using je custom piston compression ,height of 1.283,

0 deck height

havnt got the pistons yet but thats what i did to get the comp i want

Thanks for the feedback mate, I assume they are a domed piston????????

Spoolup Mentor

Spoolup

Posted
Posted

Im not trying to sell you my rods - just trying to explain that you are going to get in all sorts of shit of you use those ones with the 155.5 c/c

CP 8.2:1 are a flat top that come flush with the deck.

CP 9:0.1 are a domed piston. The flat of the piston come flush to the deck with a small dome in the centre.

CP RB30ET pistons have a small dish with valve reliefs.

To get 8.5:1 your prob best to use the 8.2:1 and skim the head - but obviously work backwards and cc everything first to calculate how much to take off the head.

D1AUS Rookie

D1AUS

Posted
  • Author
Posted
Im not trying to sell you my rods - just trying to explain that you are going to get in all sorts of shit of you use those ones with the 155.5 c/c

CP 8.2:1 are a flat top that come flush with the deck.

CP 9:0.1 are a domed piston. The flat of the piston come flush to the deck with a small dome in the centre.

CP RB30ET pistons have a small dish with valve reliefs.

To get 8.5:1 your prob best to use the 8.2:1 and skim the head - but obviously work backwards and cc everything first to calculate how much to take off the head.

Brad

By all means i do appreciate all your help, thanks very much

I'm just going by all the figures at the moment. Obviously, I will dummy everything up check chamber cc etc.

Just by the specs, thats what i get from the calculation. I know standard rod is 152.5mm

From your experience, what is the standard deck clearance for RB30? standard parts

superjet760 Rising Star

superjet760

Posted
Posted

deck height is 0 rod length should be 6"{152.5m} dont use any other rod length

and yes my piston will be dome

if u use the cp piston u can buy the right one off the shelf for 8.5:1 comp

u will only achive this if ur block height is standard and combustion chamber cc's are close to standard{65cc"s from memory}

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