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Hi All
I have been on here before with this problem my 1256 HB starts up fine drives great until its warm then it will misfire a few times then looses all power and stops wait 15-20 mins and it starts and runs ok i have checked everything cant find anything wrong so i decided to replace everything i could think of so replaced the carb and distributor new coil petrol pump new leads and plugs new solenoid checked everything got the car hot yesterday took it out for a test drive and its still the same broken down so i did some road side checks had fuel at the carb strong spark at the plugs but would not start eventually it started drove fine, I cant think of anything else to do this problem has started since i did the restoration and respray ran fine before its a mystery to me now has anybody got any ideas please.

Regards Chris.

Are all the earth points good? Just wondering if there's a bit of paint where there shouldn't be, causing a resistance instead of a good earth that might get warm and fail.

Did you replace everything at once? do you have known good parts? I am the master of changing a bunch of things instead of methodically doing one at a time to see if it helps.

Of the list it sounds to me like the coil and fuel pump are the most likely culprits.

also, what colour are your plugs?

Did you put new points, condenser, rotor arm and cap on aswel? try to get new old stock wherever possible in particular the condenser, newly manufactured are rubbish. make sure distrubutor wiring is spot on aswel.

Bit of a long shot, but might be the petrol cap, should have a vented cap fitted & if it isn't it will create a vacuum in the tank giving you fuel starvation

Hi
Thanks for all your help I did change condenser and ballast before made no difference I did think it must be the coil so got a new one made no difference so I thought I would change the distributor complete with all the internals this was removed from a spare engine I have as was the carb and fuel pump this was all running well when it was removed so all the parts should be ok the plugs are the light brown as they should be all the earths are clean and tight ive been over everything very thoroughly everything very clean and set up perfect its a real mystery.

KInd Regards Chris.

'Tis a strange one Chris. I'm sure you can recognise the difference between an ignition misfire and a fuel misfire but those others following here's the gist of it. In general an ignition misfire is sharp, sudden, hard, whereas a fuel misfire is soft, smoother and less severe in the way it feels. There are if course varying degrees of both and there are types of each that can feel and seem the same, making it difficult to distinguish between fuel and ignition faults.

As you seem to have replaced most of the potential causes it's a mystery indeed. As suggested earlier, is there a vacuum in the tank? Following on from that, is there sufficient flow of fuel from the tank?

It could be that a trickle is all that is getting through but when more is needed there is not enough getting through. With this in mind, check that the pipe and filter in the tank are both clear and unblocked.

I had a fault like this once. Turned out to be a cracked dizzy cap. As it heated up the car would miss fire.

Hi
Thanks for your help ive checked inside the petrol tank its spotless and ive got new 8mm fuel pipe seems to be plenty of fuel it is a soft misfire before you grind to a holt I have changed the dizzy cap Iam ordering more ignition parts and will go over it all again iam lucky as i have my old 1256 HC that runs great use it all the time so could try swapping bits over from that.

Regards Chris.

I had something similar before,

Turned out to be the earth wire on the distributor baseplate was a tiny bit loose,1/4 turn of the retaining screw fixed it.
Took ages to find it.