TOPIC: former ECU managed vehicle switched to carb

A potential client had someone switch his mid-late 80's (I've forgotten the year at the moment) vehicles from being fuel injected (I think it was TB injected), to only using a carburetor. There's a lot of capped lines from the original system. Will the groove work properly on this vehicle? Does anyone see any potential issues?

That is a very good question, Jonathan.

The answer is an unqualified "Yes". That being said, you will find that gains will occur without much effort, but only to a minimal level. To reach tremendous gains, you will need to rejet the carb, just like a normal carbureted engine.

Be sure to check with carb spray for vac leaks before you begin, for many engines of that age will have leaky intake manifolds.

Ron

Hi Ron,

Thanks. I hope he'll do it. I would love to get it right with a carbureted system.

One of the first mod's I did was a carburetor (the only one I've done), and though I reduced the primary jet from 95 to 90, and the secondary from 135 to 95, the owner claimed he never got any better mileage - in spite of enormous power gains. He probably has a vacuum leak or leaks though, as my ability to find them was pretty pathetic back then, and he hasn't come back over since (in spite of my invitations).

Given that experience, I noticed a post from you about a carbureted system (I can't find it now), that I thought might have also been a factor in his lack of increased mileage.

I think the carbureted system was on an RV, which wasn't getting mileage gains in spite of reduced jets. You then discovered it had too much fuel pressure, and so (if I understood it right) fuel was being dumped in at a fixed rate whether the jets were reduced or not. You then changed the fuel pressure regulator or added a regulator which resolved the issue. I remember another poster questioning how that could be, as the float valve determines how much fuel is allowed into the bowl, not the pressure on the line. You explained to him why this was different. Anyway, that left me thinking fuel pressure regulation is a potential issue when modding carbureted vehicles.

Another question I have is that I noticed a recent post about motorcycles, (again, I can't find the original) where you said (in spite of being carbureted) they won't generally get better mileage, and that it was because they didn't have a computer based fuel metering system (that would allow them to respond to the mod), or something like that. So I was wondering if that might be an issue for this vehicle as well.

Are either of these topics relevant?

Cheers

Hello, If the car has gained power after the groove, when flooring the pedal to the metal!
then there is a gain in mpg when keeping the speed limit. Or Im I wrong.


saludos desde suecia

Hola Markus,

That's what I expected, but according to the owner it didn't happen.

P.S. On another topic, when you wrote up your excellent report of modding your vehicle (congratulations!) you mentioned the need for good lighting. In case you're not already doing it, when you need some extra light you can use a headlamp.

Saludos!

Yes i did that first then i realised that with a small 1 watt led flaslight taped to the dremmel i can see with help off the shadow if i have the bit straight on the plate,
any way lots off light

Sounds even better. Thanks.