Newbie exploring v8 engine options - SU, Weber, EFi transplant - advice needed!

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d3xta

New Member
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2
Hi Guys

OK, its my first post here - so here goes.

I've got a 1986 110 3.5L v8 running on twin Strombergs which I do most of the straightforward work to myself incl. servicing, fitting twin fans, refitting the interior, etc.

Now she's done 165k+ miles, and even though she gets regular oil changes she's really beginning to show her age. She is very very thirsty and as I want to convert her to LPG, I thought it'd be a good time to get the engine sorted (I also want to fit an auto box as I drive her mostly on the road).

So, engine options are as follows;

Plan A is to keep the same 3.5L and simply fit a pair of SU's (which coincidentally I've already got off eBay), then fast road cam and stainless steel exhaust

Plan B is to keep the same 3.5L and fit a new Weber 500 carb, fast road cam, SS exhaust

Plan C is to transplant the 3.5L with a 3.9L EFi unit, then cam and exhaust plus gearbox from a donor vehicle, probably an old Range Rover which I could test before I buy.

So what do we think? Is the 3.9L unit worth going to the extra expense of paying a garage to fit it? Will it give much more power and efficiency than the other options and then give further tuning options? Are the electrics a pain in the arse? Or a lesson worth learning?

I won't be able to fit the gearbox either as I don't have the equipment so it may be worth getting the engine and gearbox swap done at the same time? I've heard that a 3.9L v8 with auto box is a pretty standard change - how much time does this on average take in your experience?

Any help and advice would be greatly appreciated.

Thanks guys.
 
Wuz speaking to a geezer who duz LPG conversions & he said the only real way ter go if you're converting is EFi. Carbs'll work ok, but you wunt git nearly the saving in running costs.
 
Go the efi route , go 3.9 hotwire , as a backfire (not uncommon on lpg) will knacker the flap type air meter. You will also find switching from lpg to pet and the other way a lot easier(its instant not so with carbs)
The wiring is not too difficult if you can read a wiring diagram.
The range rover early intank efi pump fits the 110 pet tank.
Try talking to ashcroft transmissions re getting times for converting to auto tranny on 110 Your santana take out gaerbox is a good saleable item I would suggest that you will need to envisage keeping your 110 for a fair while to make this all financially viable , so it needs to be in real good nick to start. JMHO:)
 
Hey Guys

Thanks for your advice. I think the 3.9 EFi route is looking probable now. Have heard that LPG can dry out Carb needles anyhow aswell now.

The donor vehicle here is most probably going to be a Range Rover Classic and on the whole 3.9 auto setup, would you use the donor's borg warner transfer box aswell or keep my 110's LT230?

Thanks again.
 
thank god you didnt decide on a fast road cam. Not sure what it would be like in a 110 but I have one in my 1978 MG (stupidly thinking it was the right thing to do when i rebuilt the engine) and I HATE it!!!! cr@p idling, cr@p on fule as the engine works harder (or it seems to at least) and now cant be driven in traffic as it just stalls......roll on the next rebuild so it can be put back to standard!!
 
Hi guys, Quick intro, I'm v8 shaun and i'm just starting a v8 rebuild including truck.My last one was a 3.9 efi which did not last long.The block cracked after 100,000 miles.This was running on gas and petrol. I also have a 3.5 efi on gas that has covered 143,000 miles and still runs like a dream! The 3.9 to me was not much faster and certainly more juicey than the 3.5. I sure the 3.9 is a bored out 3.5? Is this maybe why the blocks crack? My new rebuild will have a 3.5 efi on gas as i think it's better.Any one else had probs with 3.9 blocks?
 
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