BigJ

Sorry, I didn’t explain myself very well. I was trying to figure out if the gearbox mounts for the 4&6 cylinder models were in the same place on the chassis or if on the 6 cylinder they sat further back on the chassis hence the need for the different bulkhead. I’m assuming in this that the distance at the front for the fan, radiator, front panel etc is the same on both models. Or, is it just the position of the engine mounts that differs between them? From what I can gather what others have done is keep the gearbox in it’s original place, change the bellhousing and fit the 6 pot by moving the original mounts forward by a few inches. Apart from hole patterns is there any other difference in dimensions between the 4&6 pot bellhousings?

I think it was the fact that it’s a period engine and one that performs well in addition to needing minimal fabrication that swayed to for me. At 130bhp and bags of torque I think it will be on the limit of the Series gearbox as it is but anything more than that I might have been looking at a gearbox upgrade too.

I’ve another question on this is anyone can help? If I needed to replace my 4 cyl bulkhead as part of the rebuild, could I fit a 6 cylinder one with the correct cutouts etc along with the 6 cylinder floor and tunnel to my SWB? If so would the gearbox then sit further back and mean that I would need to reposition the gearbox mounts and modify the two props? Would the rear prop end up being too short to function correctly? All this on the assumption the new engine would sit on the existing engine mounts. One reason for asking is that the engine weighs 300kg which is 100kg above that of the 4 pot so keeping the weight distribution as even as possible and not too far forward would be helpful.

I believe that by fitting the 6 cylinder bellhousing the engine mounts will need to be pushed forward a few inches which may involve using an electric fan which is no big drama. Battery and air filter holder will need repositioning slightly too and of course the exhaust dealt with. I think from what I’ve read the existing bulkhead will still work as the engine will be further forward but I need to get my tape out to check for sure. The engine I have was cheap so if it doesn’t look like it’s doable then I’ll just keep the four pot and flog the 6 for spares. If I can make it work then I should end up with a nice period conversion but we’ll see.

I’ve just managed to get my hands on a 3.0 Rover P5 engine, the 130 bhp version. I’ll rebuild it and put it to one side for when the restoration starts.

Interesting. With the gearbox staying put did you need to move the radiator forward? Likewise for the engine mounts, do they need cutting off the 4 pot chassis and moving?

Thanks for the replies, shame that parts for the engine are so hard to come by now.

How difficult was it to fit? Any major mods required like moving the gearbox or chopping the 4 pot bulkhead?

Anyone ever heard of a straight six engine in a SWB? I drove a LWB with one years ago and was impressed with how smooth and torquey the engine was. Is the 6 - cyl bulkhead different to the 4 pot?

Reading through some adverts for the SU HS6 carb conversion for the 2.25 petrol engine it seems that some use a separate inlet manifold and K&N filter arrangement, presumably for improved airflow. One version however, retains the existing manifold arrangement and allows for the original oil bath filter to be retained. I’m wondering then whether the oil bath arrangement is so restrictive as to make a noticeable difference to performance compared to the K&N? Has anyone tried either setup and can comment?

Thanks for a comprehensive answer. I think the high ratio transfer box route will probably be best for me then as I don’t want to be modifying a new galv chassis and have limited fabrication facilities available. The 5th gear would have been nice for road use but I can live without it.

Cheers. So am I right in understanding that to fit an LT77 gearbox and LT230transfer box into an 88 S3 I need the shorter bell housing off a Defender as opposed to the longer RRC or DIsco one? If my 2.25 stays in the original position then the rear prop will need to be shortened slightly to account for the longer box but it will still work okay even at the increased angle? Will the LT77 sit on the original Series gearbox mounts or are mods required? If so what is the best way forward with this? For the front prop I can use a RRC auto with the thinner shaft to clear the crossmember but will need to fit a kit to modify the transfer box to selectable 2/4wd? I can either elongate the Series tunnel to match that of the Defender cutout and trim it with Defender gaiters or alter the linkage to reuse the Series levers although the high range will need to be manually pulled to regain 2wd rather than being sprung with the red lever? Althernatively I can fit a Defender tunnel, are these a straight swap (ish)? Will it line up with the floor, bulkhead and seat box panels? Finally the LT77 has a handbrake cable so how does that interface with the Series handbrake lever? Sorry for all the obvious questions but I’m trying to weight up the pros and cons of this conversion against a high ratio transfer case upgrade to the standard box.

Great thread. You mentioned a galvanised bulkhead earlier, is that a new one and if so can you post a link to the supplier please? I’m going to be following in your footsteps with my S3 SWB and a new galv bulkhead could be an option.

Does fitting the LT77 with a 2.25 engine allow the standard series tunnel to be retained? Is the gear lever in the same position?