Morris Minor Owners Club

wanderinstar wrote:Don't know about that Paul. The bloke who did the tuning reckoned that the HIF44 I have is a touch on the large side and an HIF38 would benefit at lower end. So if what you are saying is true I would already have the equivalent of the 38.

It was only my opinion based on personal experience of other LPG converted vehicles. On a 2.0 injected car I lost 10 mph top speed when the LPG mixer was added and nothing else altered. When ignition timing was then adjusted to run best on LPG I then lost nearly 10mpg when running on petrol.

Doesn't the Vizard book give his test results for standard engines instead of manufacturers specs ?

Paul Humphries

paulhumphries wrote:
Doesn't the Vizard book give his test results for standard engines instead of manufacturers specs ?

Paul Humphries

Don't know Paul, but will go and have a look. Hey not having a go mate.
By the way what do you think about that info I sent you re chassis lubrication?
Ian.

wanderinstar wrote:Don't know about that Paul. The bloke who did the tuning reckoned that the HIF44 I have is a touch on the large side and an HIF38 would benefit at lower end.

Indeed. And if you're running the MG Metro inlet on a 1098 not only is the carb a little large, but the ports in the manifold are too. So whatever the issue with the lpg bits before the carb, the air/ fuel could simply be flowing too slowly for the cylinders to fill properly and so make the most power, especially at the bottom end. I'm sure I've read of people putting excessively ported heads and inlets on and actually *losing* power due to this!

Oh, the power is there. It is just the figures I can't make head nor tail of.

No - the bigger the better (within reason) - might lose a little bit of 'tractability' low down - but when running flat out - bigger is best. I reckon the lpg mixer was the main problem. When they decided the ignition was 'spot on' - did they just say that - or did they swing it fore and aft at various revs to reach that conclusion ?

Well to tell you the truth Roy, they checked it with a strobe, but didn't actually move dizzie.

they checked it with a strobe

In which case they probably made reference to standard ignition timing etc which would almost certainly not match the modified spec of your engine.

I presume that the rolling road were given the build spec of the engine,to check the set up before starting work on the mixtures etc. I'm also suprised that they didn't use the emmision probe, to check gas levels.

Errr - this was at Minisport - enough said ??

What exhaust system are you using?

Err Jonathon, they did. It was running at about 8% to start with. Also to fine tune needle they would need emmision probe.
Islip, at the moment I am on standard exhaust. I have an MG Metro twin downpipe manifold and new system to suit is next on agenda.

A standard exhaust might explain the strangled power numbers?

Sorry Ian thought 'they didn't bother with gas side' was refering to this.

No, LPG.

Aye ! I realise that now, forgot about the conversion work and was just relating to info supplied in your post.

I would certainly have expected them to do a dizzy timing swing - to get the best power curve from that dizzy. Even better would have been a list of best timing figures at different revs - and then the dizzy curve adjusted to give these readings at each stage. I appreciate this is maybe a bit much to expect for £60 !! But I do think they should have made some effort. What did they do with the needle Ian - change for something else, or attack it with a file ?

wanderinstar wrote: I am on standard exhaust.

Are you saying that you are on the standard morris minor "strangle my engine out of 20% of power" exhaust? If you are then look no further! No point in doing all you've done without changing the exhaust.

My rolling road cost £200 and lasted 2.5 hours. They checked and adjusted pretty much everything: Max power, power through low speed, mid speed and high, needle change (we went though about 3 before finding the right one), we had the carb off to impove petrol flow, adjusted the dizzy by moving it by hand at 5000rpm to find correct timing and so on...

but 'people' say you shouldn't take it over 4000 for any length of time.

Who says this? Is this true? When I had my 1098 it spent most of its time past this figure! The 1275 in there now is regularly 'given death' in the 6's!

Are you saying that you are on the standard morris minor "strangle my engine out of 20% of power" exhaust? If you are then look no further! No point in doing all you've done without changing the exhaust.

I've noticeably improved my power through home tuning on several occasions with timing and needle experiments. That's all on the standard 1098 exhaust and inlet setup. Is the Minor exhaust really that bad?

dunketh wrote:

but 'people' say you shouldn't take it over 4000 for any length of time.

Others on this board, notably (IIRC) BMCEcosse

I thought it was 6k you weren't supposed to exceed?

4000rpm really isn't that much.