Crap for gas mileage

[bowen71]

Hello all its been a while since my last post. But I need some smart people to help me. Here goes the story.

2110, 42x37.5 heads, 1:4 rockers mild to moderate cam, 8.2:1 compression, 009 dizzy with a Bosch Blue coil and 44 IDF's and A-1 Sidewinder 1 5/8 exhaust

I have a 71 Super that I drive every day 60+ miles a day. Now its been getting about 8-11 MPG I have checked the valves, compression, timing and spark. It all seems good so I assumed that its the carbs. I recently changed the jets on the carbs from 55 idles, 135 mains, 200 airs and f11 tubes because at 75 mph the heads would get hot. So I moved the mains up to 145 and it helped adding the extra fuel but it developed a stammer at around 2500 rpm. So further troubleshooting and talking to more experience people they suggested 60 idles, 155 mains with 200 airs and F11 tubes. That made it run like a beast it was fast as all get out but, the gas mileage is still bad and it moved the stammer to 3500 rpm's. Now that is bad because at 75 mph it stammered and that was 3500 rpm. So I took the car to a VW shop and they hooked up an LM-1 and the reason for the stammer seems to be because it runs extremely FAT so FAT it is fouling the plugs. We ended up changing the jets to 60 idles, 135 mains, 195 airs and f11 tubes but it really didn't change my gas mileage. I am still running through a half a tank for about 60 miles. What is wrong with this thing? no leaks the LM-1 says its way better for air/fuel. Why is it so crappy on gas?

Any suggestions would help thank you.

[Bruce Tweddle]

What's your timing?

[madmike]

What's Trans like Gearing wise? tire size? Leave early and drive 65mph

[elmo]

Are the brakes dragging, maybe only one wheel?

[martin]

I'm surprised that the shop you went to would let it go back to you like that. Do you smell gas when it's running? Do you do a lot of idling in your drive? Does it have a slow leak from the tank, maybe siphoning thru the air vent tube(s) after you park (check underneath before starting it up).

[KAFUR1]

What kind of gas are you using.  that   10% ethanol  stuff burns alot faster!

[Mike Lawless]

I think I'd be looking at fuel dribbling out of the venturi due to a float level too high, needle and seat seeping or fuel pressure being too high. With those things going on, no matter what jet you run, it's gonna be dead rich.

[bowen71]

Timing is 32* total 8* initial

No leaks in fuel and I don't see gas dripping in the carbs at an idle.

Brakes are good no drag in them.

And the traffic is stop and go for about 5 miles of the trip.

I adjusted my accelerator pumps today they were turned way in.  It still runs fine with them turned out. 8 turns right now from where they were.

[Ohio Tom (DdK)]

Gas milage has everything to do with the idle jet size.
Try a 55, Or if you can find one, a 57.
most driving is done on the idle jets.

[Aussie Rob]

Man this was my problem exactly. I drove my 2332 duel idf48 less than 60 miles and i would go through a tank of petrol. I thought i had a leak in the tank, in the -6 fuel line but nothing until i pulled over at the traffic lights after an acceleration test with a rice burner and the other guy mentioned i was dumping raw fuel out of my magnaflow.... I then looked through the rear view mirror as i took off fast and yes i noticed the plume of petrol vapour. I did the jetting check and found the dick head vw expert who had a dyno stuffed up my jetting, float levels and adjustments...the cause of the bad fuel economy was the accelerator jets adjusted to far out and spraying gobs of petrol into my carbs and unburnt into my muffler.Once all fixed up by me in a 4 hour play and carb strip the engine ran heaps stronger all the way through the power band and very crisp response.

[Brandon Sinclair]

Like Mike said above, first tee in a pressure gauge and verify your fuel pressure and get it to 3lbs then pull the carbs and re-set the floats.  While they are out you need to verify that jet sizes are actually what they are marked (most are not-you could be using 60 idles that are actually reamed to 70's).  Also what is your venturi size?  Your original jetting of 55 idle, 135 mains, 200 airs and F-11's would be a good starting point if the jets are actually what they are marked.  If you need jets I would suggest buying them from John at aircooled.net since they will check the accuracy of the jet sizes before sending them out, but before he can assist with jet sizes you need to verify the fuel pressure and float heights first.

[bowen71]

Well today I am going to drop idle jets to 55's I have babied that thing and its still getting crap for gas mileage.  1/2 tank for 60 miles is retaded for that car. 

[John P]

Something is way off, especially if you are babying it. My similar 2110 (with slightly smaller valves, slightly more compression, a 1.5 inch exhaust and less timing (28 degrees) averages 24 MPG (mostly highway) if I'm reasonable. This is with IDAs with 37 vents.  I used to run 44 IDFs and got good mileage as well. This is with a 4.37 R&P and 175 rear tires, at sea level.

While I agree with Tom that idle jets make a huge impact on fuel economy, it's hard to imagine that you'll find 10+ MPG (recognizing that your Super Beetle is heavier).

"LM-1 says its way better for air/fuel."

What specifically did the LM1 show after the jet changes?

JP

[Brandon Sinclair]

Did you: 1. verify fuel pressure, and 2. check the float setting.

This can be the cause and you cannot jet properly until these things are done anyways.

[superdrag]

.

 it's hard to imagine that you'll find 10+ MPG (recognizing that your Super Beetle is heavier).

I don't think the extra weight of the super beetle front end will make hardly any difference.  They got just about 40 mpg out of a super in the Hot VW's mileage build.  I think if his car is tuned perfect he should be able to get 20 mpg easy.

[bowen71]

Well for an update. 

I am getting about 17-20mpg.

I havent changed much except put in a MSD6A box and regapped the plugs to .050

It runs nice but still a little rich I think I need 50 idles instead of 55's it feels sluggish down low.