does it do it when cold.
Or when warm.
could be the module going faulty when the engine is hot.
When its popping , is there any spitting at the air filter, as that's a lack of fuel.

 

Very hard to track down a problem when it's intermittent as you never know for sure if you've fixed it or not.


I'd start with the easy stuff - lube the advance mech on the distributor if you haven't recently then put the strobe on and rev it up and down whislt watching the advance come in and out - see if you can get it to stick at any point.


Dave.

 

It did it hot and cold! Typically!

I have 6-inch stacks and no air filters, It has popped and spitted in the past when the mixture was weak, also when the carbs loosen on the manifold it does so. But when it happened recently its more just popping and misfiring. No backfires though.


I will check the advance, typically I have pertronix 8mm leads, which my timing gun does not like. I will borrow a friends which is better!

Thank you.

 

and no air filters,

These carbs are notorious for idle jet blockages, even with K&N filters I had one or two idle blocks myself, the idle jets are so small the slightest speck can cause misfires / problem running. Blow them out with compressed air.

Why do you not run proper air filters ? If it's simply a fashion / image thing then you shouldn't really expect it to run reliably, you WILL get running problems and you are going to get premature engine wear because of it, that's the kind of thing you would expect. Think - trailer - show - trailer - home - unless you're going just a few miles.

Not that I object to show cars whatsoever, they have their place, but I object to the VW mags etc trying to persuade car enthusiasts that they can have cars like the ones that they feature, and simply run them day to day like a regular ford fiesta etc....

Re. pertronix - I have found their ignition modules, when fitted in original German Bosch distributors to be fine, no issues.

I have found their Flamethrower coils to be complete and utter unreliable $h1te, would never let one near my engines ever again.
Leads ?????? Dunno but not heard much that's good.

Stick to Beru, NGK (or decent Bosch) for your ignition components. Even Bosch which used to be a quality manufacturer has been getting a few negative comments of late, esp for non - German made spark plugs.
Ditch the shiny bling. Assume that pretty much everything that is chrome plated, blister packed or "billet" to be complete & utter cr^p. The vast majority of it simply designed to move cash out of your wallet and into the retailers bank account. Making your car perform better or last longer does not really figure.

Dave.

 

Right as ever Mr.Whippy.

It's a cal-look car with decklid standoffs, I don't drive it that much, compared to lots of other cars, then its garaged and the trumpets are covered. Otherwise yes filters all the way, if only to stop me dropping stuff down them! Controversially Keith Seume did a piece once, where he stripped an engine, after 20k of no filter, and found no wear. I Like the look of them mostly.

The idle jet air intake holes are tiny in the top of the carbs, CB Do a breather tube for them which raises the hole higher, not that I have seen them for sale in the UK.

I have had my pertronix dizzy for about years, never had a snag, Flame thrower coils are notoriously poor, I think the resin ones are better? I have the square 60,000-volt coil, yes probably too much, though again its been on for years with no problem. The only snag I had was when one of my previous HT leads had broken down it caused a massive spark arcing in the engine. I still have the 5mm hole in the dynamo strap

Spark plugs are another subject, I bought some new Bosch W8cc spark plugs, I always used the greenspark company, the ones I received when I checked the spark plug gap (I am old fashioned, I have checked them for years and always found them spot-on) However the last ones had all manner of different gaps.

 

, Flame thrower coils are notoriously poor, I think the resin ones are better? I

Quite possibly. I had two of the regular style ones, both died after a few months of use, twice coming home on the tow truck. Very embarrassing.

I pulled one of the failed ones to bits and the wire to one of the LT terminals had snapped, probably due to engine vibration and poor support for the wire inside the can. So I suspect the resin ones probably a lot better in that regard but I simply put an old Bosch one back on and ran it for years no problems. I couldn't force myself to dosh out yet more good money after bad for yet another FT coil.

Dave.

 

Well, I took it to mates, 15 miles away, just tuned the mixture of the carbs, with the AFR meter, it was running fine. Then on the way home it started again, it became worse and worse until I got home, Strange as it again ran fine over 2.5k revs. Under that, dreadful popping and misfiring...



Idle jets I thought! the symptoms were saying that, So I took them out blow them through, changed the spark plugs to new bosch ones as they were sooty, topped up the fuel.
Ran like a broken lawnmower....

So took the carbs off, stripped and utrasonic cleaned them, rebuild kit, new idle jets, and holders, went down a idle jet size, 57's, put them back together. found a bit of corrosion though, the carbs being a year old. And some jelly-like fuel residue.
And the floats, the action seemed a bit stiff, so changed all the bits.

Emptied the tank, via the fuel pump through some white linen. Nothing much to show.

Changed the electric fuel pump and filter, meant to do this a while ago, and changed all the hose, to 100% bio-friendly hose. cleaned the tank out, it was clean. also cleaned the hard line through the car.
Put in fresh fuel, with some fuel stabilizer.

Checked the valves, and replaced the battery..
New HT leads, and changed spark plugs again.. Back to Japanese made NGK ones.

It started up perfectly, sounded smooth and quiet. funny how the exhaust sounds quieter with a nice running engine!
Just drove it 30 miles... ran perfectly. Stopped and recreated what happened before. Ran fine!

So what was wrong? I have no idea, the problem all pointed to idle jets. But i found nothing wrong with them.

It may have been the float blocking and flooding the carbs?
A dodgy batch of spark plugs?
A dodgy batch of fuel?
Though I have an inkling, I may be wrong! That the battery was playing up, as I run a dynamo, also a 60,000-volt coil, whilst the dynamo works perfectly, at lower revs and a lower output, my battery output may have been low, enough to cause a misfire. enough to soot the plugs up too.
The new battery certainly puts out a higher voltage at all revs.
Strangely, I use a Ctrek Charger, which I plug into the car when it's in the garage, it charges then goes I trickle charge mode, My old battery never seemed to go into trickle mode, just low charging.

Fingers crossed it has gone away!