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Title: What happens with my heating when my foot is on the floor? Post by: JezWest on October 23, 2016, 09:38:53 am I run a 1972 1200 with a 1776cc motor with Dellorto DRLA 40s. I have CSP heater boxes and a Python exhaust.
All is well, apart from the nagging feeling that I need an 82mm crank in there! Now the weather has just cooled off in the UK, I'm using the heating again. I've noticed that when I get my foot flat on the floor, when only pulling low RPMs, that I smell fuel in the car. Not exhaust, fuel. Once I back off the throttle, it clears quickly. I never notice this on small throttle openings. I've taken to shutting the heat off on the one big hill I regularly drive. Mostly it's not an issue: I only get my foot on the floor ( in winter ) on that hill and if I'm being an idiot in traffic. But why? I've checked all the fuel lines rigorously and there are no leaks. I figure the basic issue is having a carburettor throats right next to the fan. Maybe when I have my foot down at low RPMs, I generate a lot of fuel stand off and the fan draws it into the heating air? I don't think I'm doing myself much harm: I have so much heat that I always have a window open an inch even in the brutal English winter (!). I guess a vented decklid, lighter right foot, some ducting around the carbs might help. I suppose not having dual carbs would fix it, but that isn't happening as I'm not really a turbo guy. Title: Re: What happens with my heating when my foot is on the floor? Post by: Fastbrit on October 23, 2016, 10:34:51 am Yes, fuel stand-off, mixed with accelerator pumps dumping extra fuel – foot to the floor at low rpm will do it every time. Not enough rpm (vacuum) to pull fuel vapour through.
Title: Re: What happens with my heating when my foot is on the floor? Post by: Zach Gomulka on October 23, 2016, 15:34:19 pm Yes, fuel stand-off, mixed with accelerator pumps dumping extra fuel – foot to the floor at low rpm will do it every time. Not enough rpm (vacuum) to pull fuel vapour through. I agree. Never experienced that on a type one though. Open stacks or filters? Title: Re: What happens with my heating when my foot is on the floor? Post by: JezWest on October 23, 2016, 19:14:56 pm I have filters. Maybe I'll run that hill in third.
Title: Re: What happens with my heating when my foot is on the floor? Post by: JezWest on October 24, 2016, 07:24:12 am The standoff is there because there is fuel/air mix travelling down the manifold and that flow gets interrupted by the valve shutting and the mix 'bounces' off the valve? If I have that right, do fuel injected cars have stand off? I guess that if you inject fuel into the cylinder, then no; but if you inject fuel above the valve, then yes. Does that make any sense?
Amazes me how many of these things I've never wondered about before. |