2200tc rough idling when hot

Tom W

Active Member
#1
Hi all,

My 2200tc normally runs very well, both from cold and at operating temperature. However, if I get stuck in traffic on a warm day, the idle speed drops and becomes very lumpy. The temperature gauge doesn’t move much when it gets warm, it goes from just below half way where it normally sits to just over half way. When I get going again everything behaves normally. I don’t feel the car is going to overheat or let me down, but it really looses its refinement and the engine is so lumpy it shakes the car. Add a tad of throttle and it gets smoother. I think the issue is idle speed related, rather than an a component failing when it gets too warm, or vapour lock.

HIF6 carbs have a bimetallic component in the jet adjusting mechanism. I wonder if this is causing the issue? Possibly the rate of adjustment is inappropriate for modern fuel? I can’t think of anything else that would change with temperature and only cause the idle speed to drop.
 

sdibbers

Well-Known Member
#2
Hi Tom, you’ve just switched to ethanol fuel in the UK right? I fitted hif6 carbs to my car here in the states a few years ago and had major problems with idle on hot days (even flooding from the overflow ports of the float chamber!). It took me a good while to find the culprit. ethanol lowers the boiling point of fuel quite a bit. I added self adhesive glass fibre heat shielding to both sides of the standard heat shield, didn’t have a problem after that.
My guess is that HIF carbs are more susceptible to this due the float chambers being in the base and closer to the exhaust manifold.
This is the stuff I used. Alchemy Parts 2 x Self Adhesive Exhaust Engine Heat Shield Sheet 40 x 33cm Ideal for Motorbike Car - Aluminium & Reflective
https://www.amazon.co.uk/dp/B07MC1PQGZ/ref=cm_sw_r_awdo_navT_a_MMF0KZSKNFNKGXCJ4115
 
Last edited:

Tom W

Active Member
#3
That’s a good point. We’ve just switched to E10 for regular unleaded. I prefer to use super unleaded which has stayed at 5% ethanol, along with an additive, as I’m not sure how ethanol proof the original fuel system is. However on Friday, due to the current fuel shortage, I had to use regular unleaded (with the additive). I’ve now filled up again with super unleaded, so I’ll see if things improve.
 

sdibbers

Well-Known Member
#4
As for the fuel system and ethanol I made these changes:

(1) Replaced any rubber fuel line with ethanol safe hose.

(2) Replaced the o rings with Viton O ring as the originals swell and break down in ethanol.

(3) If you haven’t already get a new seal kit for the HIF’s as the newer Burlen kits use viton also for the rubber.

Thats about it for changes. I did go a little richer on the needles on mine as it felt a little flat at higher revs, but that may have been for other reasons that I later fixed (spindles were very worn on my carbs at the time)
 
Last edited:
Top