Stage 1 V8

Hi

I've got a 1987 V8 110, and I've not long had a new exhaust fitted, while on our holidays in Wales, yes, the V8 decided to make life difficult. Starting was no problem, but every three to four minutes she would backfire, scatter all the sheep, and then carry on as normal. This happened all the way back home, didn't really make much difference if it was LPG or Petrol. Went out tonight to just check, and yep, the silencer is mega blown after a quick test run.
I've heard that it could be the LPG solenoid maybe, I've new spark plugs, HT leads, rotor arm and cap for about two months with no problems, but this has now cost me a new exhaust section I think, it's split at the seam, is it repairable?
Help any ideas?
Thanks

When does it backfire? Under acceleration, cruise or deceleration?

Some thoughts:

Backfiring is usually due to timing, and this would be my first guess if it happens on both LPG and petrol.

LPG can give spark leads a hard time - when you replaced them, did you use quality silicone items? If not, is possible the leads broke down very quickly - I have heard of this happening.

I think, unfortunately, your silencer is gone for good - even if it could be welded (difficult), you've probably damaged it internally.

Hope this helps.

I had serious backfiring problems with my LPG-converted '83 110 V8. In my case, it was related to starting a cold engine first thing in the morning on LPG - it would start but ran incredibly rough & backfired on the overrun. Eventually blew out my front silencer with a helluva bang (if it had happened in the hot & horrid places where my job takes me from time to time I would have been into a ditch and calling for close air support pronto !) and then sounded like a Challenger in trouble.

Solution (after paying for a new silencer & exhaust section - happened the day before the MOT !) was only ever to start first thing on petrol, then flick to LPG once warmed up. Interestingly, it will then start on LPG for the rest of the day with no problems (not so sure about in really cold weather ?) even if it has been standing for some hours.

Had the timing checked (normal source of backfires) professionally after checking myself and it was spot on, so can only conclude that with a very cold engine unvapourised LPG was getting into the cylinders and causing the backfires. Might be worth checking the vapouriser ?

V8s are prone to backfiring anyway. There is a wealth of info on the V-8 forum (something like v-8.co.uk or .org.uk - can't remember exactly), including an LPG section.

Good luck !

Actually now that i think of it. I would imagine it is your plug gaps. LPG is harder to ignite then petrol and you typically have to close up your plug gaps or get a stronger coil. If it is this then it is causing the spark to jump in you dizzy across to another cylinder. Try closing up your gaps and see if that fixes it.

Actually I just re-read your original post and you say it happens on petrol too. It could still incorrectly gapped plugs

Plug leads, plug caps, timing problems but don't forget worn camshaft.
Does the engine make a ticking noise, of does it run completely quiet?

Hi to all who assisted.

can you believe it, but a distribution cap ordered from my local car shop proved to be faulty, it was only two months old, on closer inspection it could be seen that the rotor arm had made deep grooves in the electrode things, and worn away the plastic that is on top of each electrody thing, unsure to exact name. Anyway a trip down to a Land Rover specialist for a new rotor arm and nice blue dist cap solved the problem.
Now she's running perfect....

Mon Dieu ! Chris, Can't believe that a piece of advice that this non-expert gave turned out to be sound !

Glad all is running fine now. Stick to genuine ignition parts.

Nick

Well the Land Rovers been running well, even went up to Fort William from Northumberland with no major problems.
We do though have one problem, cold starting!
If we switch to petrol for the first start, she may or may not start, and then if I switch to LPG, it's the same problem again, when I first turn the key, she kicks in then dies, and from this only a LPG bump start will get it going.
Once running, she's no problem, I have also tried to switch to petrol later to see how she runs, but the LR judders, goes slow, with loss of power, it's as if petrol is not getting through, or some solenoid is preventing petrol.
If there is anyone with ideas, please let me know.
Cheers

Chris,

Check that the fuel solenoid in the LPG system is working. I had very similar symptoms - poor running on petrol, then no running. Turned out to be a faulty petrol solenoid. About £15 to have it replaced.

Nick