6 replies to this topic

[norris2002]

This website has been a font of knowedge for me, and hopefully you can help with my latest problem. in the next few weeks i hope to get the car properly set up at ML motorsport (will be the second trip this year ), but am having some problems with the idle and responsiveness of the car.

 

history first:

 

clubman estate 1100 rebuilt after 10 years off road. been on road for about 2 months, but never ran perfectly. still going through the 'teething' stage.

 

recently had

- head gasket change (gasket went)

- replaced bottom radiator hose (old one split after gasket went)

- accuspark added

- tappets re-gapped

- speedo drive replaced (was not working, still isnt!)

 

after the gasket and hose change, took a lot of fiddling to get it started again, but seemed to be ok except was overheating. this seemed to be where air was getting in at thermostat due to the gasket not sealing as one stud was stripped and the nut not grabbing. Replaced thermostat studs today and got engine up and running. when up to temperature I set the timing at 12 deg btdc with strobe (it was running at about 30 deg!)

 

after changing timing idle changed, so i turned the screw on the carb to get this nearer what sounded normal (no tacho on car). after this i checked carb with the finger piston lifter, and there was no difference. didnt change the mix at this point as previously ok(ish).

 

revved the car a little and the idle returned very low, practically stalling. engine popping and spluttering. could almost hear the piston in the carb knocking where it was going up and down. i checked the oil and topped up with 3 in 1 (it was a bit low).

 

after much messing around i have changed the mix a little (a bit leaner i think), and fiddled with the idle screw to where it is faster than i would like, but seems less prone to dropping out. I drove the car home from workshop, about 3 mins, and i needed to rev the car before dropping the throttle, engaging a gear and then pulling away. pulling away slowly the car would judder a little and take a long time to start reacting. I also noticed that when pulling the choke out it would make no difference at all to how the car was starting, would not lift the revs or any of that good stuff a choke normally does.

 

I will start again with carb settings i think, and check the choke is engaging properly, throttle screw on choke is disengaging properly, etc. what i wanted to know is has this happened to other people before? is it a carb problem? or more likely an air leak somewhere? or distributor? or something else??

 

thanks for your help.

Neil.

[sonikk4]

It could be an air leak. Was the carb and manifold taken off for the head gasket change??

[jime17]

Is the vacuum advance working properly?

[gazza01]

Is the choke cable fully opening the choke. Also the choke full on will help with start up, but if you leave it fully out it wont run too good.

I start mine with the choke fully out then within a very short time push it in halfway, just to keep revs up. Then drive away.

Halfway out the choke is not affecting mixture, just holding up revs.(on my hif44)

I would be tempted to advance the timing slightly just to get a feel how the car responds. You can always put it back again.

Maybe get a gunson on it for idle mix as well.

What is the full spec?

[norris2002]

OK, so a couple of things to update.

 

the choke wasnt appearing to work as per normal, because the throttle screw that engages with the choke was not engaging. sorted this out, and was still having loads of problems. 

 

On Saturday after getting the car started, I drove it to a nearby race engineering company (I live behind Brands Hatch, so there are a few about), and the lovely people there really helped me out. a quick run through with a pair of spark plug pullers showed that number 3 was not firing very well. Then a quick spin with the compression tester showed very low compression on pistons 2 and 4. This explains why it was running terribly. I took the head off and ran it back down to the workshop, and after inspecting the old head gasket and deciding nothing was obviously wrong with it, did a vacuum test on the 5 ports. This showed an obvious vacuum leak on the central exhaust port (presumably from chamber 2 exhaust valve) and a smaller leak in the exhaust port for number 4. 

 

I took the head back and stripped it/re ground valves sunday morning, and put it all back together.... and it runs! Very strong on all 4, timing set properly and carb there or there abouts.

 

now it just needs a little bit of tweaking!

 

HOWEVER... in the mean time i have bought an engine from a 1300 GT Allegro, that will be the basis for my first full engine stripdown and re-build.

 

Any recommendations for what to look out for? I know i will need at least a set of gaskets. I have assistance from friends who used to race minis, and the local race firms if needed, but would like to do a lot of the work myself. if anything I am just interested to know what is going on inside my engine.

 

I have the Vizard 'Tuning BL's A Series' book too, which is a good read, although not a step by step guide by any stretch.

[MiniMonty]

My advice is - never hurry...

Getting it right first time will save you hours (weeks) of confusion and heartache.

Go slow and methodical - then get it right first time, every time.

 

Valve timing is a huge big deal - don't ignore or overlook it (so many people do) - measure very carefully. 

This is a thing that if wrong by a hair can cause long term decay on an engine.

[norris2002]

Monty, good advice... As it has now returned to the same condition.

I drive the car to work this morning (10 miles ish). Took a bit to get started, and white smoke, but I blamed this on the cold. The smoke soon cleared. Car drove fine for half a mile or so, then backfired a bit and started chuffing again. I went to local motor factors in way to work to buy dizzy cap and rotor arm (and ht leads whilst I was at it), as these had previously not been replaced. This definitely improved the response, but was still chuffing as I pulled into the work car park.

I have not investigated more since this, and have left the car at work as I want to bring it back leisurely at some time later this week. I was going to get a new coil as the one on the car has not been replaced yet, and was considering some hotter spark plugs, incase the problem is oil.

Symptoms before the valve re-lapping were:

Cylinder one strong spark and performing well. When ht lead removed (whilst running) engine practically cuts out. Compression around 150

Cylinder 2 low compression (25) but decent spark. Whilst pulling the lead the engine noticably drops but not as much as when pulling 1.

Cylinder 3 good compression (150) but no difference to engine running when the lead pulled

Cylinder 4 exactly the same as 2.

Car spec:

Clubman estate 1100. Stage 1 mini spares kit. HS4 carb with AAU needle. Accuspark electronic ignition kit (Hall effect sensor replaces points and condenser)