Rb30 Rods - Height Make A Difference

[D1AUS]

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

[The Mafia]

Interested in the answer.

Maybe its for pistons that have different gudgen pin positions? (Like the GTR pistons compared to the RB25)

[r33_racer]

which rods had what centres?

Ive built rb30dets with both argo and spool rods and never knew about there being two different heights available.

[Spoolup]

There are no SPOOL rods with 155.5 centre to centre they are all 152.5

The other brands that you see with 155.5 are just the wrong size. They could be used with a cutom piston, but to no advantage.

[D1AUS]

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 October 24, 2007 by D1AUS

[Spoolup]

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]

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

Edited October 24, 2007 by D1AUS

[Spoolup]

The CP pistons have 0mm deck height - meaning they are flush with the deck.

If you install the other rods they will protrude above the deck by 3mm, which will make it hard to run :-)

[D1AUS]

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

[Spoolup]

forgot about the calculations.

All off the shelf RB30 pistons are designed for std length rods ( 152.5mm ), so any rod differing from std will effect the piston crown deck height.

[[200]]

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

[D1AUS]

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]

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]

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????????

[[200]]

What compression ratio do you want?

[D1AUS]

What compression ratio do you want?

Going for 8.5:1 with some head work. RB25 Head is going on

[Spoolup]

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]

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]

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}

[D1AUS]

No worries, thanks for your input guys, appreciate it.