Thread: Can I use an SII or SIIa firewall on a SIII 4cyl?

The centre section of a six cylinder one is different, and would need changes in the floor to be used with a four and your gearlever will be right against the firewall - I think there would be problems with the transfer levers. But the different bits are usually OK, so you could usually convert the firewall using the bits off your old one.

The difference s2/a to S3 is the parcel tray etc on the S2a. You could remove these and fit them to a S3 firewall to use on a S2/a, or remove them to use a S2/a on a S3.

There is no difference between the S2 and S2a firewalls as such, but there were progressive changes in S2a production, the major ones being in 1967. But you can modify either way without a lot of work, and only a purist would be bothered.

John

parcel tray?

Tony

There are a few differences in the 4 and 6 cyl firewalls and there are numerous issues with changing a SII or SIIa firewall onto an SIII.

Firstly the windscreen pivots on the pre-ADR SII/SIIA are different and wont comply with the ADR relevant to your SIII. Then you have to remove all the glove trays on the SII/SIIA firewalls and modify them for the cable harness and heater/deister holes of the SIII.

For all the extra work on doing all that it would probably be as much work as replacing the rusty bits on the SIII firewall.

Diana

i am not going to worry about the dash.but yeah i think i might just try and find a wreck with a good firewall

Originally Posted by schmierer LR at singleton

i am not going to worry about the dash.but yeah i think i might just try and find a wreck with a good firewall

Tony

Up your way there should be plenty.

You probably already know this, but if you head West from your place the firewalls and chassis usually have less rust than the ones from the lower Hunter where they have likely been on Stockton Beack or exposed the the salt air.

Diana

I have a 6 Cyl SIIA firewall in my SWB IIA. Its not really a problem except if you have a heater or hand-throttle - they wont fit because the clearance between the firewall and gearstick is less, as is the clearance between the firewall and the edge of the parcel tray.

You will need the 6 cyl floor sections and "hump" too.

This is how mine was when I bought it, and the firewall is in good nick, but personally I would rather have the 4 cyl firewall as I have a really nice "shin burner" heater that I want to fit!

This is what it looks like:

Originally Posted by akelly

I have a 6 Cyl SIIA firewall in my SWB IIA.
<snip>
You will need the 6 cyl floor sections and "hump" too.
<snip>

How does that work when the gearbox on a 6 cyl is further back than it is on the 4 cyl and the seatbox is in the same place?

I can understand that you have to shorten up the front of the 4 cyl tunnel cover, but you cant use the 6 cyl because the gearstick hole is in the wrong place.

Dunno, but there you have it! Another mystery for the rivet counters...

I didn't do the work to mine, neither did the PO, so I have no idea how it was done, or why. I've never had mine side-by-side with another series IIA so I'm not sure exactly what's been done. When I first looked at it I thought it was a 6cyl car originally, but I was informed (on here) that there were no 6cyl shorties - I have said before that the holden conversion looks like it belongs there, as opposed to some butchery I've seen on others, so perhaps all the 6cyl running gear was used from a donor vehicle? It doesn't have 6cyl brakes though, which you would think would be the first thing to come on-board if you were to do that kind of detailed modification.

Anyway, hijack over - I might be wrong about the hump and floor sections, but I have a set of 4cyl floor panels here (was going to get rid of the ugly chequer plate) so I'll measure them up and see if they would fit.

Cheers,

Adam