swapping from FI to Carb

JunkYarDog · Posted: Fri Jan 07, 2011 10:29 pm Post subject: swapping from FI to Carb

I searched I swear! My search resulted in 2 unrelated threads.

So here goes, has anyone ever converted to say a progressive weber from FI? I have a friend (long time Aircooled mechanic) who has done this on a few aircooled engines, like a 2.0 bus and a porsche 914 (almost identical I know). But what other than the clearance would be some of the negatives to doing this? I am looking into this as my van gets older because FI parts are showing their age now. Thoughts please...

Oh yeah.. its an 85 GL 1.9L
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I have never owned a VW I didn't like, but there have been a few Fords and Chevy's.
85' GL Sunroof
68' Beetle sedan
72' Chevy C10 (LWB Step)
(67' Volvo 122S pending)

Wildthings · Samba Member Joined: March 13, 2005 Posts: 52602

You need to come up with a heated manifold it you want your engine to run well. I would think that the progressive might still have its flat spot problem when used on a WBXer just like it so often does on the T-4 engine.

thatvwbusguy · Posted: Sat Jan 08, 2011 4:14 am Post subject:

Progressive Weber may not fit under the decklid (at least not with an air filter)? I have always thought of the center mounted progressive carb as an absolute last resort, even way back in my aircooled days.
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Randy in Maine · Posted: Sat Jan 08, 2011 5:41 am Post subject:

OK I will ask....

What is wrong with the FI that you currently have?

59 dormi · Posted: Sat Jan 08, 2011 8:09 am Post subject:

I'm pondering the same thing I used the search no concrete info maybe tencent can shed some light on the lack of info?
My problem is some of the fi parts are only available mail order my trucks been off the road since christmas while I get my head around the fi system if it were AFC on a bus I would say AFC is way better than the single carb set up but there are dual webers nowadays how about the WBX? at least I could get my truck back to work
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Wildthings · Samba Member Joined: March 13, 2005 Posts: 52602

The trouble shooting chart in the Bentlley is pretty straight forward. Just do each test as specified. With experience the whole diagnostic only takes about 15 minute.

wenholzm · Samba Member Joined: February 14, 2010 Posts: 140

I knew a mechanic who told me he bored a hole into the intake manifold and put a carb there. He cut a hole in the lid. Said that it ran better and got better milage. Do not know more details and cannot confirm...

meyervw · Posted: Sat Jan 08, 2011 8:54 am Post subject:

I wonder if it will even run. Without the Fi part the ECU may or maynot let you go. No signal for the fuel and no fire. There really is not a whole lot to a fuel injection system.
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insyncro · Posted: Sat Jan 08, 2011 9:04 am Post subject:

I have the Euro heated manifold, stock carbs and an adapter for the progressive carb to be used. All fit under the deck lid.
I have not completely installed everything but test fit it.

I also have the Gene Berg dual carb manifolds and linkage, also test fit.

I'm not looking to sell any of the parts.

Just voting for .....Go for it!

dylan

vwjoel · Posted: Sat Jan 08, 2011 9:16 am Post subject:

I second Wildthings. A heated manifold is a must. I've tried on a few type 4 engines in busses to get a single webber progressive to run well but it will have flat spots in cold weather. Two of the busses I've seen with the single webber have had head damage from running lean. I've had a single webber progressive on a few Type 1 upright engines and it was great but the kit came with a heated manifold. If you were going to go carb I would stick with the dual ICT carbs. They''re not as easy to jet as an IDF but they're a nice simple setup.

Before you invest in carbs and go down that rout go through the trouble shooting in the Bently. You may find it is somehting simple.

toomanyveedubs · Posted: Sat Jan 08, 2011 11:15 am Post subject:

Why not just switch to a stand alone FI system like megasquirt?

Easy access to parts, and better control of economy/performance.

JunkYarDog · Posted: Sat Jan 08, 2011 4:58 pm Post subject:

JunkYarDog · Posted: Sat Jan 08, 2011 5:05 pm Post subject:

I forgot to consider the heated manifold, good point. I don't know that this is the best idea either. I did have a dual carb set up from a euro vanagon. But I messed up and sold it to someone who wants 5 times the price now instead of putting it to goos use (some peoples kids!). To be honest, I enjoy playing with modifications and searching for results. If they are not good then reset.. but you sometimes get suprised.

I appreciate all of the info and feedback so far. As this is a highly uncovered topic please put it all out there!
_________________
I have never owned a VW I didn't like, but there have been a few Fords and Chevy's.
85' GL Sunroof
68' Beetle sedan
72' Chevy C10 (LWB Step)
(67' Volvo 122S pending)

wcdennis · Posted: Sat Jan 08, 2011 7:08 pm Post subject:

This is a great topic. While we are at it, lets discuss the merits of front drum brakes, polyester bias ply tires and 8-track tape players.

Randy in Maine · Posted: Sat Jan 08, 2011 8:27 pm Post subject:

Sir Sam · Posted: Sun Jan 09, 2011 1:39 am Post subject:

JunkYarDog · Posted: Sun Jan 09, 2011 8:54 am Post subject:

59 dormi · Posted: Sun Jan 09, 2011 9:35 am Post subject:

Wildthings · Samba Member Joined: March 13, 2005 Posts: 52602

I am worried that I will not be able to get parts for my Webers and Holleys much longer.

Howesight · Posted: Sun Jan 09, 2011 10:11 am Post subject:

Hey JunkYarDog:

See this thread:

http://www.thesamba.com/vw/forum/viewtopic.php?t=444550&start=0&postdays

Fixing your EFI is way easier. A high(er) lift cam will NOT cause problems with your EFI. The "hunting" idle on a 1.9 is not due to cam changes. The 1.9 constantly adjusts ignition timing to control idle speed. A small vacuum leak or maladjusted throtte switch (plus other things I won't mention here since they are well- covered elsewhere) can contribute to wandering idle. Your fuel mileage will suffer with carbs and you will have to engineer your own ignition system and advance curve or use a distributor designed for an air-cooled engine.

The EFI has enough excess capacity already built in to accept displacement increases, altitude changes, wide ambient temp changes etc, etc., let alone a cam change.

Having tuned and adjusted many, many carbs over the years, the only time EFI and carbs give the same performance AND mileage is on a naturally aspirated engine at sea level, at wide open throttle and high RPM. Change anything else, and EFI ALWAYS gives a superior result.

EFI is especially good on transient throttle response where carbs use an "accelerator pump" to squirt raw, un-atomized fuel into the intake manifold. I have adjusted Weber acccel. pumps with differing strokes, operating cams, discharge nozzles and even aiming the nozzles to get the best performance/mileage combo ad nauseum and I can tell you that while I got good at perfecting Weber performance, I never was able to produce the all-weather/all temperature/all-the-time reliable transitional throttle response that a simple EFI system gives.

(Oh, in case you hadn't noticed, I think EFI is better than carbs on a WBX.)


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