I had a slight misfire a couple of times last week when I started the van but it went away so I thought no more about it . Yesterday I fitted a pair of ²nd hand 34 icts that I bought of here and after balancing and tweaking it ran well . this morning the misfire is back !!. I narrowed it down to no 1 cylinder .When I take that lead off their is no change at all .so I . changed the distributor to my spare 009 . Changed the coil to my spare . changed the plug lead swapped no1 plug with no2 Tested the compression (140psi) and still no change when I take the lead off but I do get a big spark when I put it back on with the engine running . Any help would be appreciated as I'm officially stumped.
from what you describe, your getting a spark at the plug lead so the logical conclusion would be the plug. If you changed the plug from no 1 cylinder to No2 cylinder and the plug fires on number 2 then it suggests the plug was fine .. find another plug and connect ot t the lead. make sure its earthed then get a mate to crank the motor while yo watch for a sparkat the plug end .. If that plugs firing you can elominate the cap, and lead try the same with the plug that seems not to be firing, if it sparks then perhaps your looking at valve adjustment on that cylinder.. ? maybee an air leak at the manifold ? if your using those crap tin gaskets throw them in the bin and use composite ones..
I tried a spare plug and it sparks ! The manifold gaskets are the grey fibre ones . I was working on it in my friends garage and drive it home and when you get past the misfire it sits happily at 60 .
Worth doing a smoke test for leaks. The manifold gaskets are notorious. Are they the taller manifolds with the ict’s or the stubby empi type? Have you run through the valve clearances to make sure you haven’t got a tight one? Jetting of the ict’s is critical, take a look at Wayoutwestie’s website he is an ict guru.
They're the short empi manifolds ,fibre gaskets under them and thick insulation ones on top . If I had a tight valve Wouldn't it show as a lack of compression ? Hope do I smoke test it ?? It did have the misfire last week so was thinking I was probably electric.
Not certain, but I've experienced both of these problems and it seemed, at the time, and in both cases, to be a single cylinder problem. Or, at least it impacted one cylinder more than the other, on that bank.
The sticky float happened when I gave it some beans after pulling away out of a junction, it missed, them cleared itself, then stuck so I a gentle thump with camping mallet was required to free it. This is after changing, dizzy cap, rotor, leads etc. I have heard say WD40 is good to test for air leaks, but never tried it myself, too cautious.
If it has spark and compression then its either fuel or air. An idea : Could be too rich, petrol overflowing straight down inside manifold and flooding No1 at low speed. At high speed you are sucking enough fuel that the fuel drops in the carb and the leak stops and it runs properly. Check fuel level in the float chamber on 1/2 side carb against 3/4 side. If it seems higher check for leaky metering valve.
Will do Mike, it starts instantly without touching the throttle so definitely too rich .I'm confused as to why only one cylinder is affected .other than the misfire its pulling much better and smoother .
I was thinking electrical problem but yet again TLB comes to the rescue . I'll get a look at it Wednesday night and let you know if you were right . Cam
Float chamber at the front so its draining from the overflow down inside the front of manifold so it goes down the front trouser leg..
