missfire when cold

Post by **rayofleamington** » Tue Jun 01, 2004 12:13 am

I think mine has some carburation problems (put a plenty miles on it today) and the missfire at cold has not come back - Presently I suspect an air leak though making it lean, and running better at warm as it can cope with lean better then.
I'll chaeck the pugs tomorrow but I'm expecting them to be white....
Anyway - a good run on the motorway and it didn't loose oil or water, and another wierd thing.... The diff doesn't whine! I kind of miss it the strong hum like I get in Riley

Post by **Gareth** » Tue Jun 01, 2004 5:42 pm

If it bothers you that much, I'll have it - you could swap it for the diff on Phyllis... it sounds like Bryn Terfel going at full tilt!!

Post by **winger300** » Sat Jun 05, 2004 11:36 pm

swings & roundabouts!, im thinking its carb related again. I finally got around to grinding down the flanges on the intake manifold to match those of the exhaust mani. Theres most definately no air leak at this point now.

I put my HIF38 carb back on with the hope that it would be ok now, but at about half throttle it hisses loudly and the power drops, pushing it beyond this point, the hiss stops and the power is back... what causes this at part throttle? air leak in the throttle spindle bushes?

I've got one more HS4 carb that im going to try

Post by **rayofleamington** » Sun Jun 06, 2004 12:20 am

Well a bit more playing on the electrics and the missfire never showed its head again. The vac advance works by sucking on the pipe so that's fine. No idea why its gone although the coil isn't tight in its bracket.
I also wonder if i got some muck or water in the carb when it ran out of fuel, as that could have cleared itself.

Anyway, no changes to the fuelso farl and it runs great now (having reset the timing - the previous lack of power was due to late timing, light throttle allowed the vac advance to pull the timing forward just enough to get some power)

Post by **Kevin** » Sun Jun 06, 2004 9:43 am

Winger often the HIF carbs only seem to use a solid cast metal spacer to the inlet and with the Minor being a little prone to fuel evaporation during warm weather its best to get the plastic type of spacer to help reduce the problem, I assume that you used a 4 bolt fixing this time, and a silly question you did put a gasket between all mating faces as I have come across problems caused by only one being used between the spacer and manifold but not one on the carb to spacer.

Post by **winger300** » Sun Jun 06, 2004 2:19 pm

carb number four seems to be more of a problem. At about half throttle it seems to loose power, theres no hissing sound, but theres a definate flat spot in the throttle response. Any ideas what causes this?

Post by **winger300** » Sun Jun 06, 2004 6:25 pm

I changed the dashpot and piston with the first HS4 i was using, and its fixed the flatspot on the throttle. We'll see if its fixed the missfire when cold.

Post by **Kevin** » Sun Jun 06, 2004 6:59 pm

Winger what type of HS4 are you using the early one or the later waxstat type, as the one I am not completly happy with is the waxstat type, although I do not know how worn it is and I am using a metal spacer at the moment and dont know if this is affecting it.

Post by **Cam** » Sun Jun 06, 2004 9:11 pm

Are you using the same needles?? as flat spots can be caused by different needles if you are swapping different carbs.

Post by **winger300** » Mon Jun 07, 2004 9:45 am

yeah, im now using the same needle as the first carb i had on. Both carbs are the waxstat type and i have a metal spacer.

It appears to be fixed now though, and i'm using the waxstat from the original carb since the fuel pipe on the other one was leaking. So the problem must be due to an air leak on the old carb body. The car starts now without any choke, which is more normal for a summers day!