EFI back to SU's ??

cbv8

cbv8

Member
Hi All,
Having got my P6 Estate back last month and after starting it for the first time without a hiccup after sitting in a garage for years it's now decided play up :cry: without going into too much detail :wink: I am not really a fan of EFI I do like the extra bhp and ease of starting WHEN working properly but hate the intermittent temperamental elecs and all the wiring :| I am therefore going back to the original SU carbs my Estate does have a 3.9 a ZF box ported heads 4-2-1 big bore exhaust and twin tailpipes which I ran like this for a few years but after the EFI system was installed it has never been back on the road legally :oops: All I want to do is get it back on the road asap with the least complications trying to sort my ZF speedo is bad enough but EFI is an added complication I can do without :shock: The reason for my post is am I doing the right thing or not :? any comments advice encouragement don't do it do it experiences of EFI vs SU etc etc would greatly be appreciated or would it :wink:
 
You should be able to get a set of SU's and a manifold fitted and running in a couple of hours at the most, and then once you've run it on those for a while you can make a decision about what way you want to go from there, so I'd say go for that option. Just make sure you get an HIF set-up.
 
I agree with Harvey (that well known refrain...) except that as we all know, he likes HIF's because of the superior results when they're in good condition and I like HS's because HIF's so often aren't in good condition and I can get me head round an HS much more easily....

Am I right in thinking your EFi set up has a Meggasquirt doing the thinking for it? If so, the results are going to be vastly superior to anything the car will manage on SU's. If not, then, when you have the rest of the car to your satisfaction, give yourself a winter project to make the injection work on Meggasquirt. Because you can see everything that is going on on the laptop it ought to be much easier to faultfind than the Rover set up, but you will need to know what a laptop is.....


Chris
 
Hi thanks for the quick replies I'm not new to messing with P6's having had my first in 1986 a 1974 3500 I would not touch Hs6 carbs got to be HIF6 the EFI was fitted by me and my friend Bob R.I.P many years ago it was of a 1984 SD1 VDP EFI. I think it's probably past it's sell by now my mate has a set of HIFs and manifold so hopefully I will fit them this weekend after I have swapped the intank inj pump seems a shame but I do not need all the added EFI probs just hope I don't regret my decision I suppose time will tell :?
 
you should be able to keep the in tank pump and fit a pressure regulator screwed right down in front of the return back to the tank. There are a lot of posts in Land rover areas regarding putting SUs back on after EFI :)
 
Hi Chas,

Provided you keep all of the EFI parts, you can always go back down that path at a later date should you wish to revisit.

A car running with properly set up HIF6 carbs will run, in many ways more smoothly, than the same engine running EFI. Of all the carburettor systems made over the years, the SU is the closest in terms of fuel efficiency and power delivery when compared to EFI systems, although the latter still have an advantage when it comes to precise fuel maps.

Ron.
 
When i bought my P5B Coupe, a 3.9 engine was fitted with the original P5B carbs with external float chambers and the car ran well. The 3.9 was not legally fitted to the car and after opening it, although it ran well, i found quit a bit of wear. I will now fit a 3.5 from an Sd1 with HIF's. I also have a Range Rover injection system but also prefer the carbs because these are very reliable. I will fit LPG and then the advantages of fuel injection are gone any way.

Peter
 
Thank you all again for all the info and advice :wink: but my mind is made up it's HIF's for me I know I will drop around 40bhp but with the other mods and the 3.9 engine it should still be nearer 200bhp ish and will be more reliable and easy to maintain :)
 
cbv8 said:
...but EFI is an added complication I can do without :shock: The reason for my post is am I doing the right thing or not :? any comments advice encouragement don't do it do it experiences of EFI vs SU etc etc would greatly be appreciated or would it :wink:
Click to expand...

My recently departed SD1 EFI was originally running a standard 4CU system, which worked very well up until the point when it went wrong :? and it did so, often :( So I then went over to SUs (HIFs) , and they worked very well and were more reliable than the EFI. But, in my infinite wisdom :roll: I then decided to try the 14CUX system. Initially the 14CUX works very well, but it takes a huge amount of time and effort to set up correctly.

After all that, I had come to the conclusion that it's best to stick to an original spec fuel system for a lot less aggro, whether OE EFI or SUs.
 
You have to remember that even the newest hotwire systems are pretty old now, let alone the flapper systems.

I fitted EFI to my Landrover but used Megasquirt to drive it all, there was a lot to learn and a bit of tuning, but on the whole it has been totally reliable. Even better, when I have had other non MS related faults, the MS has helped me to rule things out as I can just pull my phone out and see what is going on over bluetooth.

Initially I had a flapper top end, but later swapped to a hotwire manifold as it gave me a wider choice of injectors. Both performed the same, but with the injectors I currently run I can idle a little leaner than before, almost stoich.

I defintely rate EFI over carbs, but if you just want to get it running day to day for now I would say stick the carbs on and enjoy!
 
Thanks again for the advice and info tried in vane to start my P6 today with coughing and spluttering it is a fuelling problem which has just confirmed I'm going back to simple carbs can't be doing with start none start :roll:
 
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