Gas Mileage

[Stefan]

I feel like my gas mileage is really poor. I feel like I am getting a few miles per gallon, but I do not think I have a leak. Is this normal for the VW based TD?

Thanks,
-S

[Paul Mossberg]

Stefan,

First, let’s find out what your actual gas mileage is. We’d be able to offer better opinions.

Meanwhile … I had a VW based TDr with a dual port, dual carb, 1776cc engine. Normal mixed local/highway use was a little over 20 mpg.

Paul Mossberg
Former Owner of a 1981 Classic Roadsters Ltd. Duchess (VW)
2005 Intermeccanica Roadster

If you own a TDr and are not in the Registry, please go to https://tdreplica.com/forums/topic/mg-td-replica-registry/ and register (you need to copy and paste the link)

[Stefan]

I know that I am getting less than 10 without a doubt, maybe around 5-6 MPG. I was curious to know if I am alone with this issue. I now know that I need to evaluate this deeper sometime in the future.

-S

[Al Greig]

I have a VW based kit, 1776 cc engine with a mild cam and a two barrel weber carburetor.  I get about 25 mpg overall.

[billnparts]

That’s pretty bad for a VW based TD. My 300hp 302 V8 delivers me 10 MPG.

Bill Ascheman
Fiberfab Ford
Modified 5.0, 5sp., 4:11
Autocross & Hillclimb
"Drive Happy"

[edward ericson]

20-25 is normal. My Spyder with a hotted up 1914 with dual 44 Webers did about 23mpg on average. The TD, when it had the 1600 SP, did a little better than that. Ten is definitely cause for maintenance. If you’re close to five it’s leaking for sure. It’d never run that rich.

I’d start by checking everything per the book. Check and change the oil. Does it smell gassy?* Check and set the valve lash. Pull the spark plugs and have a look. Black is rich. Check the timing. When was the last time the cap, rotor and wires were replaced? Points and condenser? Get new ones. If it’s a Pertronix or similar then leave it be.

After all that’s done, look at the fuel system.

BTW, what is your fuel system on this car?

*Common problem with VWs: Needle valve in the carb sticks open and fuel drips down into the engine, through any open intake ports, into the combustion chambers and then into the crank case. This is no bueno but also easy to remedy.

[Stefan]

I knew that something wasn’t right, I read online that bugs could get up to 30 MPG, and I knew there was something probably wrong. There is no oil smell coming from a leaking tank in the driving space, nor does it seem to be leaking oil on the exterior.

I have nothing special with the fuel system. It is a few gallon tank -> metal fuel line + German Hose (3 in-line filters) -> fuel pump -> H30/31 Carb.

I have pertronix, only 5-6 months old. Spark plug wires same age.

I will do my 6 month service in the next few days, or maybe even today. I will check out how my oil smells, my plugs, and my valve lash and update the forum.

[Stefan]

I will check compression as well and tire pressure. Hopefully compression is all good, I do not have enough cash around to rectify it if that is the issue

[edward ericson]

Good luck & keep us posted.

[Stefan]

No gas smell in oil, tire pressure was embarrassingly low (20 psi low on all 4 tires), and valve lash was correct.

I have not had time to check the plugs.

I went for a drive after my oil change and filling up my tires, experiencing significantly better gas mileage. I drove for about an hour around College Station, with  somewhat frequent stops and medium speeds. I did not need to fill up halfway through as I would have before, and still have a fair amount of gas remaining. I am not sure if I am getting the 20-ish MPG that I should be getting, but a significant improvement.

I will check the plugs and compression next. Any other suggestions?

Thanks,
-S

[edward ericson]

Leave the front tires at 20 or a little below. Back ones should be good at about 25.

30 psi is too much and will make it handle poorly and ride like a rock.

Good news re mileage. Sometimes a little tuneup is all you need.

Re. “a few-gallon tank”–please say more. Most of us are running slightly modified Beetle gas tanks, which hold about 10 gallons. We can mostly do about 200-250 miles between fillups.

• This reply was modified 3 weeks, 2 days ago by edward ericson.

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