Fuel Consumption

[GeRGelu:]

Hi!

I want to know how can I reduce the fuel consumption of my baywindow. It's
now 19 Mpg (12.5 litre/100km) at average (both city and highway), but
previously I measured for highway use about 22 Mpg (10.5 litre).
Is it good? Or can it be better? Somebody told me that with a 1600 DP and a 34
PICT-3 he achieved 29-26 Mpg (8-9 litre) at highway use.
I have a 1600 SP, and a 30 PICT-2 carb with a 117.5 main jet. Should I play
with different main jets, and the ignition? (Now I timed it at 0 degree, and it
runs very cool, but it hesitates for a moment when I want to accelerate. There's
only about 6000 kms in the engine since rebuilt.)
Thanks in adVWance,


GeRGelu:

[VWSurvival]

Well...

A properly tuned up Westy will return between 18 and 30 MPG depending on how it is loaded, elevation and how you drive. If you are happy to meander the by-ways as a rolling chicane at 50-65 MPH then you will get the best mileage, unless you carry a lot of stuff or live at very high elevation.

The 30PICT-2 will limit the already limited top-end on a 1600 bus. If you try to keep up with traffic your mileage will plummet.

The best thing to do is give the beast a complete tune-up with special attention to the plugs and valve lash. Timed "straight up" is correct for the stock single port distributor (you have a '70?).

Increasing the ability of the engine to breathe will help your mileage because the engine has to work less for a given speed/load. Open element air-cleaner, DP heads, QP exhaust and dual carbs all accomplish this (as do ratio rockers).

As far as the jet is concerned it seems to be a bit small. I would check the plugs by doing a "high speed" run at 65mph and shutting the engine down at speed (without moving your throttle foot!). Roll to the side of the road and pull a plug (#4 was always easiest for me). Look way down in the plug between the insulator and the threaded body. White and ashy is too lean, light gray or brown is OK, black or obvious deposits is too rich.

Mike!

[GeRGelu:]

Hi Mike!

Thanks for the answer. But I have a few
questions open:

How does the 30 PICT-2 limit the top end of a 1600 bus? As far as I know baywindows
were also fitted with 30 PICT-2 and 30 PICT-3. Should I look for a PICT-3? But some
people said that the simplier the carb is, the better it functions.

I've checked the spark plug gaps, and the distributor gap. I also know about the color
check of the plugs, but I should drive a few hundred miles on a highway to use that.

Timing straight up = 0 degrees (TDC)? I don't know the distributor correct or not, but I
think so. And I have a paper air filter. Should I change to the oil filter? (I have one spare)

And the service manual says 116 main jet for the PICT-2 (I have now 117.5).

Maybe I'll try to change my spark plugs (currently Magnelli Marelli, but I think I'll chose
the Bosch).

And how can you reach 30 Mpg? 0-62 Mph in 50 seconds? And cruising speed at 55
Mph?

Thanks again,

GeRGelu:

[VWSurvival]

Are you in Europe? U.S.A. specification '68-'70 busses had 34PICT-3 carbs, single-port 1600cc engines with dual vacuum distributors. The smaller venturi in the smaller carb causes the flow to be restricted as the RPM rise (so, therefore, the power dies sooner at the top-end).
I know nothing about the Magnelli-Marelli plugs but is seems that the air-cooled VW really likes Bosch "Super" plugs and nothing else (my experience).
All the "stock" applications I have seen for the 30/32Pict series have been on 1300 and 1500 cc engines so the jet size could still be small. Especially if you are using less restrictive intake (paper element cleaner) and/or exhaust (like a "QP" style merged "header"). Yes, "straight up" is TDC, sorry.
The plug reading is really best on a "just" warmed up engine. The critical part is to have it at a constant throttle opening in a part of the throttle you are interested in (like WOT or 3/4 or whatever) for about 1/2 to 1 mile then shut the engine off without changing your throttle setting (hard to do, takes lots of control).
Being very mellow with the throttle, light loads, coasting down hills, never exceeding 55 mph (except while coasting), drafting semi-trucks (easier back when the US national speed limit was 55mph), max sidewall pressure, and a complete tune-up yielded over 30 mpg for me on several occasions.
Driving normally I could consistantly get in the 24 to 26 MPG range on the highway.
Winter driving around town nets me my worst mileage (due to extended idling) of 18MPG.

Curiously, I found that when I changed to dual Kadron carbs, single "QP" exhaust with a collector style "header", milti-weight oil (10W30) and a "009" distributor, my mileage went up by 2MPG, consistantly. I expect when I start using the SVDA dist it will get even better.

Mike!
'70 Westy
'84 Vanagon GL
'69 Ghia
'67 Beetle
'68 double cab (Now sold, boo hoo)
need I go on?

[GeRGelu:]

Hi!

I have an American Official Service Manual for 68-79 buses (the bog green book from Robert Bentley)
and it says, that for the single port engines (letter code B) there was a 30 PICT-2 and PICT-3 carbs,
officially. And the PICT-2 as I said was equipped with a 116 main jet. But should I choose a bigger
jet? How does it will affect the consumption? What kind of carb did you use before the kadrons? With how
big jet and what timing?
You've right, I'm in Europe.
I'll change to Bosch Super plugs. And what type do you use? Coz I asked at a shop about what that book says,
and they told me that that spark plug models are now unavailable. (Bosch W 145 T1 for normal use and for "high speed
service" =what does it mean? the Bosch W175 T1) And what does it mean WOT? And SVDA dist?
TIA

GeRGelu:

[VWSurvival]

Right,
WOT = Wide Open Throttle
SVDA = Single Vacuum Dual Advance meaning it has no vacuum retard and it has both a vacuum and centripetal advance.
A W 145 T1 is no longer a good Bosch number, try a W8TC (the shop should be able to cross the old number with the new in their "superceeded numbers" section).
"High speed service" is always driving on highways with the engine pretty much maxxed out. Only use the hotter plug if you are experiencing detonation at high speeds or melting of the plug electrodes, otherwise you may experience plug fouling issues.
I may be mistaken on the 34PICT-3 but I vividly recall having one and seeing the same carb in nearly every "bay-window" through '70 with a SP 1600. Perhaps it was because I am on the West Coast and California had different (more stringent) emissions regulations.
As far as jetting the carb goes, if you have a less restictive intake and exhaust then the bigger main jet is called for due to better "breathing" of the engine.
The jetting has more of an effect on the proper operation of the engine (fuel/air ratio) and thereby power and longevity. Obviously, if your power is down you will tend to use more throttle to keep up with traffic (and this is where the fuel economy goes to heck). Escessively rich running will also tend to wash down the cylinders and accelerate wear on the rings (very bad is when the oil level "myteriously" rises) and foul the plugs with fluffy deposits.
Excessively lean and the engine will run hot, be low on power, backfire, and detonate (ping or pink). Both conditions will eventually destroy bearings as well either from shock or lack of adequate oil "wedge."

Prior to running the Kadrons I had the "stock" 34PICT-3 with half the emissions stuff boogered, stock exhaust, stock dist., and oil-bath air cleaner and stock timing (TDC @900 rpm, vacuum dis-connected). Mileage was good (24-2 but power was not.
Then I went to a dual port, 74mmx87mm (1760cc), dual Kadrons, single QP merged exhaust (kept heater boxes), open element air cleaners, "050" distributor and timing at about 5 degrees btdc.
Mileage went up about 2mpg across the board and the power was noticeable... much less downshifting and "cruising" at 65mph no longer required the accelerator pedal to be "floored."
Was really happy until my dad threw a rod ( I may have forgotten to tighten down a big-end bolt). sigh.
Mileage in winter was much worse due to two factors... increased idling and no heater flaps (big mistake) engine continually ran too cold and sucked the fuel.

Mike!

[GeRGelu:]

Hi Mike!

Thanks for the lot of info. I'll change now to Bosch spark plugs, and check the timing again.
But when I cruise at 60, I don't have to floor the accelerator, it's around a half throttle. I've tried last fall to change the timing to 5 ATDC, it accelerated better, but the engine was too hot I think. (I check the temperature always by grabbing the dipstick, like Muir says, and if I can grab it = it's good and cool) With the current set-up the engine is cool after highway use, but of course after city runs it's always hotter.
Last time, the spark plugs were brown, nothing special. (not grey, or black, but I haven't checked them immediately after highway use yet).
I'll look for a 30-Pict-3, but till I find a good one, should I try different main jets? And in which direction? (I have now a 117.5, and I guess I have a 120 or something around it. Should I try?)
TIA

GeRGelu: