Hey Fellaz,

Had a thought just now with all this talk about FJ rods and all that ...
Could it be possible to fit RB30 rods into thy holy Datsun L4's (L20B) ??

heres what i have got ... if you could help fill in the blanks that would be good !!

Datsun Stroke: 86mm
RB30 Stroke: 85mm

Datsun Rod Width: 26.6mm or 26.8mm ?
RB30 Rod Width: 22mm ???

Datsun Pin Dia. : 21mm
RB30 Pin Dia. : 21mm

Datsun Rod Length: 145.9mm
RB30 Rod Length: 152.5mm - 6 inch [6.071]

Datsun Pin Height: 38.1mm
RB30 Pin Height: 32mm

Datsun L20B TDC: 227.45mm (86/2 + 145.9mm + 38.1mm) =
RB30 In L20B TDC: 227.50mm (86/2 + 152.5mm + 32mm) =
Looking good !!!

And the most important;

Datsun Big End Dia. :52mm / 53mm ? (49mm , 50 mm)???
RB30 Big End Dia. : 49.5mm

So, inconclusion with the info that i have gathered...
i would have, if the big end dia. would fit the datsun crank...?
An L20b with rb30 6 inch H-beam rods with a rod ratio of 1.77, 86mm standard RB30 pistons (may go oversize), 86mm stroke, good cam =


IS THIS POSSIBLE >>>????
the only problem i see is if the big end dia. or the rod width isnt the same or compatible .. you wouldnt be able to use this setup ??

all info and help is welcome !!!

cheers steven.

_________________
Stephen,
Tanilba Bay Tyres & Mechanical - 4982 3599
Formally "Datsun_16_Hundred".

Thy Beast 1600
Datfusion

Any one ... got ne info ?

Your basic calculation is stroke divided by 2 + rod length + pin height should be around the same for both combo's (and around the same as the deck height, which is the distance from the top of the block to the centreline of the main bearings).

So, for L20B : 86/2 + 145.9 + 38.1 = 227

Using RB30 bits : 86/2 + 152.5 + 32 = 227.5

So, works out promising there, especially as L20B deck height is 227.45mm

Having said that, I've got no idea on the size of the big ends .. SR20 are no good. They're not as big ( ie crank is potentially not as strong ) as an L-series .

You also need to consider any valve cutouts in the top of RB30 pistons (they have 4 cutouts from memory) and how that will effect combustion, plus the dish / dome and how that effects compression ratio.

_________________
1970 ex Group A Rally P510
1971 P510
1972 180B SSS
1965 SP310 Fairlady
1966 SP311 Fairlady

cheers dave for that info, i didnt know how to work out the TDC .. thanx alot

have made a few edits in the first post ... still need more info !!!
sound to me like this combination might work....
cheers
steven

_________________
Stephen,
Tanilba Bay Tyres & Mechanical - 4982 3599
Formally "Datsun_16_Hundred".

Thy Beast 1600
Datfusion

L20B cranks I have here measure 50mm pin, no dramas as grinding down to 49.5 is 20 thou undersize, not a completely stupid size reduction.

Width on the crank does measure as 26.8mm though. If the RB30 rod is only 22mm wide at the big end, that's where the ship get's sunk. That clearance needs to be thou's, not millimetres.

_________________
Happiness is watching the race.... in your rearview mirror

Hi There,
yeah thats what i though when i got that info, if they wernt 22mm big end thickness the would be perfect !!
cheers
steven

_________________
Stephen,
Tanilba Bay Tyres & Mechanical - 4982 3599
Formally "Datsun_16_Hundred".

Thy Beast 1600
Datfusion

I think the RB30 rod will fitt,it has the same big end diameter as the L series rod,the only problem is the thickness off the rod,you need to sim it up,bearings that look like crankshaft bearings,the thickness off L series is 27mm,and the RB30 22MM,CORRECT ME IF IM WRONG