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MG Midget and Sprite Technical - I've changed too many things!

Finally got a new MOT for my 1098 Sprite yesterday after being off the road for 18 months. However on the way to and from the test it ran terribly, no power, spluttering and the odd backfire, definitely worse uphill. To set the scene whilst it has been hibernating I've fitted new points style distributor (static timed 5 degree btdc), maniflow manifold and exhaust, decoke and regrind valves therefore resetting rockers, new throttle spindles and butterflies in carbs. So lots of room for errors...
I've rechecked timing and carb set up and can get the car ticking over great, easily as good as previously. Strobe timing at 8 degree btc is around 1000 rpm tick over.
I'm starting to think fuel starvation due maybe to a blockage due to standing or have I messed up rocker settings, this is next on my list to recheck. Or...
Andy Potter

May I suggest that you start your diagnosis by checking Compression pressures the actual pressure is not the issue, but the comparison between the cylinders. Re-torque the head and adjust the tappets.

Once this is done, check the distributor... You say you have fitted a new points ‘style’ distributor (I suspect this to be your problem), can you explain more..?

When you rebuilt the carburettors, did you remove the jets and jet hoses..? you put new seals and washers in there and you DID check that there was no dirt in the bottom of the float bowls and jet aperture..?

It should be easily sortable..

Mark.
Mark T Boldry

Mark
I only reground the valves as it was not much more effort to remove the head as I was changing the manifold so I think any leaky valves are down to poor setting on my part.

I swapped a cheapo electronic distributor for a new lucas points one as the electronic one would wander all over the place.

I did clean out the float bowls but haven't touched the jets as these were changed about 5 years ago. Probably worth checking the float bowls again now though in case there was dirt in the lines, although I did cover the end when carbs were removed.

My other thought was blocked vacuum advance tube but I'll check this later too.

Thanks Andy.
Andy Potter

The ignition points may have settled in (not unusual), check the points gap again 0.015”, if it persists, try an new condenser (even IF your last one was new, they are sadly not very good and can fail within minutes of them being fitted)...

Is the ignition coil connected the correct way around.?

Mark
Mark T Boldry

The timming scares me.. but i dont know much about 1098... but below 10 im just not a fan

are the carb jets and needles self adjusting ... when you raise the carb piston and drop it... does it hang up or fall with a thud....got oil in the carbs dashpot ... youbhave the carb heat shield in place

are the butterflys sealed correctly .... no light showing around the premeter when looking into the venture...all the linkage is working and not binding

After 1/2 hour... is the coil excessivly hot

im with mark... but i think the real issue is the dissy... it probably needs to be recurved to match your engine....

if the car ran decent before you replaced the dissy... then id but the old dissy back in and work thur all the uther hicculps ... once those are resolved then put the new dissy back in and see what happens from there

prop
Prop the cow killer

Easy things first and in order

Check all leads, coil and connections.

If it has been standing....Clean out jets thoroughly, check for any air leaks - hose splits etc - yes check vacuum hose and check if any fuel filter is not clogged.

Check fuel flow is adequate - if not, suspect pump.

Check mix and plugs


Check valve clearances, and check timing at full advance - should be around 28/32 degrees.
Oggers

another thought if it hasn't been covered is - is the fuel new or old, ie if sitting for 18 months the fuel could quite possibly be shot. Ive spent many a happy few hours cleaning out carbs to try and get a long standing car up and running only to finally drain the old fuel / clean and refill to have it fire back into life

Alan
a reid

Alan ... major X 2

that is an awsome point... i cant belive i didnt go there as fuel for me here in the middle of the usa is the bain of my existance.

fuel here litterlay goes off in about 3 weeks and given a few months in the heat of summer it turns into a hard white powdery crystal

i cant even count how many times im on this board complaing about having to clean out my fuel system to get rid of all the dead fuel because i hadnt burned it soon enough

agian... great point

ive gotten spoiled by driving my car every day and now its almost reliable...haha

prop
Prop the cow killer

Finally got round to sorting this out last week end. I rest timing and ignition connections without any real improvements. Then turned my attention to carbs, balancing, mixture etc. Found that when raising the piston on the front carb literally nothing happened. So removed carbs and stripped them, gave everything a thorough clean and reset butterflies. Nows runs great. Thanks for all the helpful hints.
Andy Potter

Congratz andy

Its sat ...hope your scaring the old folk racing arkund the block and beyound

prop
Prop and the Blackhole Midget

Finally got round to sorting this out last week end. I rest timing and ignition connections without any real improvements. Then turned my attention to carbs, balancing, mixture etc. Found that when raising the piston on the front carb literally nothing happened. So removed carbs and stripped them, gave everything a thorough clean and reset butterflies. Nows runs great. Thanks for all the helpful hints.
Andy Potter

Poor andy...

is it brain cancer or just avg. run of the mill alzhimers

haha

wow... i may have to rent that old movie ground bog day with bill murry this weekend... great film

propt
Prop and the Blackhole Midget

ha ha. weird
Malcolm Le Chevalier

Hmm, not sure what happened there, hit refresh and managed to repost the same post. The car was running great bt until clutch clunk crunch :) Oh well gives me something to do. Lol.
Andy Potter

This thread was discussed between 24/07/2016 and 01/09/2016

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