Opinions please gents

[Adrian Southgate]

The Sierra is giving me jip. Running rich, high tickover (1200 rpm), mixture screw is fully in - 1/4 turn back, starts misfiring at 2000 - 2200 rpm, throttle stop screw is backed off and not making contact, throttle cable has slack and is free moving, as it the throttle linkage assembly. Looking for places to start.

I will be doing a compression test when I get home tomorrow and will change the condenser too. 

Anyone got anymore thoughts?

[Adrian Southgate]

I'll check the manifold joints tomorrow. I do have a DGAS thats not in use which I was going to fit on the legerra during the rebuild, The leggy carb needs a rebuild and I wouldn't call it a reliable tested unit. Probably good for a last resort as I don't want to disable the legerra until the sierra is a going concern.

it may be a missing blank plug as there were a lot of pipes sticking out of this manifold.

[Adrian Southgate]

 It seemed to be running fine when we first got it started. I can swap the carb over without killing the legerra, I can always swap it back if it doesn't affect the fault. I think i'll start with air leaks and flap positions in the carb, then the condenser and plugs/leads before i get the spanners out.

I was planning to build a modified 'gas flowed' carb for the Sierra out of all the spare parts I have lying around. Maybe nows the right time to just build a clean one and fit it.

[Pete Clayton]

I'd second an air leak around the base of the carb where it joins the manifold. Only other thought, was it jetted for a pinto?

[Dave Adams]

I fitted a gas flowed carb to my pinto last year (38 DGAS drilled out much larger venturies) and it made only a small difference mid range. pinto carbs are good for 140hp + so its hard to improve carburation.

[Dave Adams]

Cannot be air leak if running rich. however i had similar problem on my pinto carb. one or more of the accellerator pump diaphragms is knackered. when they go they can flood an engine. also check mixture screw and jets generaly make sure they are the right way round. Is cable holding throttle open (seen that as well)

[Dave Adams]

but the point is vern that 140hp is the practical limit for pinto tuning, after that it gets very expensive and in a non restricted car like your average Dutton any number of engines make better choices for bigger power and reliability.....better fuel consumption as well......i think its D Vizards book on tuning the pinto i have at home and even he says bigger carbs on a stock pinto head is a waste as the head already flows quite well, and a stock carb is more than is needed. Breathing isn't the only issue. a whole series of measures need taking into consideration. in one experiment he discovered the engine made more power with the air filter and filter top cover removed but the airfilter base plate left in place than it did with the air filter base plate removed! ?

[Adrian Southgate]

I was happy with the performance I was getting out of the leggy 5 years ago so no real need to go much further. For the Sierra I am more interested in reliability, which a properly maintained pinto has in bucket loads, that'll work for me.

The legerra now has a mild piper cam in the injection head and the replacement block is +1mm so I reckon the DGAS and a slight mod to the advance profile on the dizzy should be enough. All I need to do is put it together right and fit it. Maybe I would be better off with the bosch dizzy?

[Pete Clayton]

Standard Pinto I had in the Melos with a 38dgas once setup properly made 107 bhp at the fly and 120 lb/ft of torque on Northampton Motorsports rollers. Used to go well and was good on fuel could do 30 odd mpg on a run.

[Big Vern]

Try to find the bosch dizzy from a 1.6 or 1.8 with the ign pack. Very reliable. I'll dig out my notes on how to mod the dizzy curve - it's not s lot for a mild cam. DGAS may still be a bit over the top, probably worth trying both carbs to see which you prefer, I found the DGAS was all or nothing on a Pinto in a low state of tune. For the Sierra I'd keep it stock but use the bosch dizzy again (so you gonna need to find two sets) and the very late 32/34DMTL weber.

[Adrian Southgate]

Thanks for the input gents. I will start with the simple stuff and basic checks and see how it goes. Got to fit two new brake calipers first :-( so may be tomorrow before I get to play with the engine, can't very well test it under load with the front brakes locked on.

I tend to drive low to mid range unless i'm chasing the other Duttoneers up through the lakes so that carb mod will suit me if that is what it does. I can't see it doing any harm and I have a couple of spare carb bodies to play with.

The carb came on a crossflow manifold so if anything it should be under jetted. I have cleaned it out and taken the jets out, blown them through and they seemed ok while I was fitting it. I didn't write the sizes down but will do so when I crack the top off. Does anyone know the standard sizes for a 2litre. I have three other carb bodies to steal jets from to find the right sizes.

[Big Vern]

If its off a xflo or even a 1.6L pinto it'll be all wrong, you need to be using a 2.0L carb on the 2.0L engine. Try the Leggy one first as its off a 2.0L. The xflo carb will have all the wrong mains air corectors and emusion tubes so not surprised at the odd running characteristics.

[Dave Adams]

yeah the right carb to start with.......