1500 running woes

[storeyn]

Afternoon all

I am struggling to get my 1500 to run correctly, the tick over is erratic and very hesitant when accelerating.

It’s a newly rebuilt engine, the carbs fuel pump etc were transferred from the donor engine I was using whilst this one was being rebuilt… and that ran fine.

It’s running electronic ignition and double checked timing today and it’s spot on.

I have balanced the carbs, replaced the jet assembly, set the mixture as per the guide on the forum.

Also replaced all the gaskets just in case there was an air leak..

I have even changed the tank today as the original was a bit crusty, I have a fuel filter which is clean and a filter king pressure regulator( as originally the bowls were getting flooded)… it’s got new needles in the carb bowls too


Just wondered if anyone had any thoughts… it feels to me like fuel starvation… so my next step is to increased the pressure through the filter king reg or change the fuel pum?

Thanks in advance….

[Richard the old one]

Have you checked that the carb piston dampers are top up?

[Carledo]

What he said! ^^^^^

But also carefully check the 3 breather hoses that connect the rocker cover to the carbs. Even a tiny crack or air leak will cause the sort of rough running you are experiencing.

If this DOES turn out to be your problem, it'll be the 3rd one i've diagnosed for this in less than 6 weeks. The other 2 were Sprints.

Steve

[storeyn]

Thanks Both for the advice..

Checked dash pot oil and there was some in but a bit low… also changed a cracked breather hose.

Now running a lot better at tick over fairly steady. Rebalanced carbs and adjusted throttle cable and linkage as both carbs were not opening at the same time..

Still some hesitation on acceleration…on a brief run round the block… will have to give it a longer run when got more time…

Also found the front brakes binding a bit… as not been used for a while.. another job to add to the list.

[storeyn]

The saga continues…

I have replaced the breather pipes… and got it to run slightly better but not perfect.

Changed the coil to be on the safe side initially no difference but then got worse.. kept cutting out unless on choke or throttle…

Original coil put back and no difference… won’t tick over at all now unless the throttle is open…

I am now thinking fuel pump?…. But both carb bowls are full….

Where is the best place to get a pump from?

[storeyn]

So this morning to eliminate all options

Changed the distributor back to the points one, re-timed, rebalanced and set the carbs, reset the fuel pressure regulator…

Should have done them one at a time really to identify the issue… but was getting a bit frustrated with it

Now running really well..

Not sure if it was the accuspark distributor or coil… as I have had no issues with it in the past.. I will switch back as see if it returns to the same condition.

Will leave as is for now…

[Richard the old one]

i am glad you have got it running. I am still a points man as I keep reading that various people have problems with electronic ignition. Do please keep us informed when you do find out what was causing the problem.

[Carledo]

Not saying it's not guilty, but Ei systems usually either work as advertised - or don't work at all! There's not usually any middle ground.

But I could be wrong, it has been known!

Steve

[yorkshire_spam]

Not saying it's not guilty, but Ei systems usually either work as advertised - or don't work at all! There's not usually any middle ground.

But I could be wrong, it has been known!

Steve

90%+ would agree, but... last time I had the Spitfire rolling road tuned the EI was intermittent - I was embarrassed when I found out why as it's a fault I'd previously fixed on the original dizzy before fitting the re-built one.
On some of the kits the plastic magnet ring that sits on the spindle can slide too far down the dizzy spindle. Too low - no spark. In the middle - intermittent especially at higher RPM/Load. I found putting a small o-ring on the spindle and sitting the ring on that fixed the issue for 1000s of miles.

I've been a big advocate of EI in the past over points, but recently have had bad experience with Powerspark failing at less than 2 months old. (They supplied a replacement even though I asked for a refund, now running accuspark and carrying points "just in case"

[ClassicFan]

now running accuspark and carrying points "just in case"

Very sensible option. I have done that for years now after an expensive 123 dizzy failed in a Citroën and left me stranded at the roadside. I replaced it with a mechanical one, and fitted a Powerspark kit from simonbbc with the points kept in the ashtray and have done the same in the SE

[storeyn]

Not saying it's not guilty, but Ei systems usually either work as advertised - or don't work at all! There's not usually any middle ground.

But I could be wrong, it has been known!

Steve

I would agree Steve.. the first one I fitted didn't work at all so got a replacement which has been fine... not convinced its the problem just may have been a coincidence.. if the weather gives me a break this week will swap it back just to confirm one way or the other

Tried a cold start this morning and all still good...