carb problem?
Turbo Mini Forums

hey up, got a couple of quick questions, finaly got my engine running yesterday after a full rebuild and it ran lovely, but i went to start it today and its running like a bag of spanners, sounds like its misfiring, and blowing a bit somewhere.

Im pretty sure the blowing noise is just from where the manifold meets the downpipe but the misfire has got me stumped. theres a good spark across all 4, the timings close enough to not be a problem, and i havnt messed with anything since yesterday so something must have broken somewhere upon starting it?

the fueling was alright last time it ran and i havn't messed with the regulator, but when i removed the carb i noticed a lot of petrol came out of the float chamber overflow pipe when i took the bung out, and theres an abundance of petrol down the inlet manifold and in the head, is it likely to be something broken in the carb or is it more likely to be a fuel regulator problem?
thanks,
steve.

doh! why did i start messing with it!

first the down pipe.......

i fell into this trap!!

you will have fitted a 2" aftermarket downpipe to the standard metro exaust manifold,
if you have,. the metro turbo sported a 1&7/8" down pipe

so whats happenig is the clamp is pulled up solid on the 2"inch aftermarket downpipe, which has not pulled up FULLY to make a seal

what you need to do is releive the clamp on the downpipe side some 5 to 6mm using say a die grinder or dremmel or even a file if you are short on tools.

the second problem will lie with the float bowl needle valve this will be worn & sticking open OR the float will be burst!,

IAIN on this forum does a recon Kit which is well worth the brass. it comes compleat with every thing to bring a 20 year old carb back to life please PM him

cheers mate i'll try that trick with the clamp, it is indeed a 2" system. i'll get in touch with iain about the carb kit too, got to be worth a shot and even if its not the culpret at least its all new anyway.
gonna check the head gasket tomorrow too, ive done a compression test and that came up perfect, but it sounds too much like a gasket gone to leave it at just a compression test. so for the cost of a gasket its worth a look, only about 3 hours old too but ive had stranger thinga happen. and it did make slightly higher boost than i intended yesterday when my mate snapped off an actuator hose by accident and never noticed. actualy whats the engine boosting at when the dump valve blows in the plenum?
thanks for the reply
steve.

doh! why did i start messing with it!

the compression test will reveal all!!!!
usuall detonation takes out the gasket between 2 & 3 cylinder i have had this twice !

before i lowerd the compression and fitted an intercooler

the small pressure dump valve which leyland fitted lifts of its seat around 10 to 12 psi......ish

i run a 3/8" BSP tap down the hole in the plenum and fit a hex taperd plug in with a little PTFE tape on this compleats the job!

the hole is the correct size to run the tap down

remember the compression test reveals ALL if its done right!

you MAY be wasting money and time going in this area but ....................... i have been cought out a few times when my mind has not been focused

good luck!

if you say there's a load of fuel down the inlet and in the head could it be possible that is just wetted your plugs? i kept getting this after my oh so amazing RR setup at spams, it was running stupidly rich and the plugs would spark when tested out of the engine but when they were in the cylinder they just didnt do a thing and made my engine run on 2 cylinders instead. a set of plugs has gotta be worth a try before the head gasket.

Edited by Nick on 5th Oct, 2005.

sounds like a defiant needle valve problem i would start here before removing head, if it is leaking then she will be squirting neat fuel straight into the engine at a alarming rate.

if you have a compressor then try removing the fuel in line and the over flow pipe the gently squirt some air down the fuel in line this may clear the problem but my guess the seat is fucked so will be even worse when you come on boost as it will have to with stand high fuel pressure,

so i would change with a new valve and even better do a carb rebuild then go from there.

always looking for them bigger bunches of bannanas

Carb rebuild is not that hard to do at all, just take your time and do it methodically.

After I did mine I wrote a guide on doing it, step-by-step, that is in the "How To" section.

lol cheers for all the info, too late on the headgasket front im afriad, i had a spare gasket anyway so was worth a try but it was totaly fine when i got it apart.
so looks like your all right about the fueling, it still drives, and makes boost fine but it just isnt going anywhere near as nicely as it was on the day i got it started. its not even a misfire as such its just running shite :(
ive got a compressor so i'll try that trick next but yeah id imagen after 20 years of abuse the carb would benifit from a rebuild anyway so it'll have to have one.
thanks a lot,
steve.

oh just for referance the engine aint a standard 1275 lump, incase that would make any difference atall! its : 1380, omega 11cc pistons, kent 266 cam, turbo dizzy, carb etc, runing 4psi till i get my old head modded and rebuilt and an intercooler.

doh! why did i start messing with it!

arghhh! fecking mini. despite trying all day to sort the running problem i had no success, tried everything mentioned bar a rebuild, thought sod it i'll fit my new shocks, fitted them, set the ride height a bit better, thought better give it a run up the road to make sure it's settled, got half way up the road and whatever was stuck in the carb blew out and its running perfect!!!? bah who said minis dont have a personality, all it took was some nice new shockers and it starts to play ball. bloody things.
thanks for all the help tho much apreciated.
steve.

doh! why did i start messing with it!

can you keep me posted on you performance with that 266 it should go well with some interesting results you wait and see.

if you have a intercooler you should be able to run 7psi no probs with about 24 deg fixed advance but only do this after the rollers.

always looking for them bigger bunches of bannanas

yeah no problems, from the little bit ive driven it, it pulls like a train at 4psi, right from the word go, and the turbo spools up lovely and early compaired to the 1275 i had before. looking forward to getting some miles on it after the bloody mot (where it is today)

the final plan was a 30cc head, and an alloy intercooler in the grill space, with about 12psi+ should be able to get the CR down to 8 - 1 with 30cc head. but after driving it again im not so sure going for big boost is best with it, might be better keeping more power there all the time and just suplimenting it with the turbo. its not as quick as the previous 1275 which was running 10psi on a stg 3 head but tbh it feels much better to drive already.

steve.

doh! why did i start messing with it!

they do with high cr, as mines does now its like driving a automatic eg doing 30 in 4th plant the throttle and of she flies.

always looking for them bigger bunches of bannanas

yeah its nice, im used to cammy engines, both previous lumps have been a bit ott in that department, one 1380 with a 286, and a 1330 with an old leyland race profile, cant remeber the number off my head. so having an engine that pulls nicely all the way and is still as quick as the old 1380 is refreshing to say the least! not that i didnt like the cammy engines, i just wanted to try something different, and ive got to say im hooked
steve.

doh! why did i start messing with it!