Author Topic: Would YOU replace your bus FI system with a single progressive carburetor?  (Read 582 times)

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Offline kinggeorge13

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Up to a couple months ago I was a Fuel Injection Believer and while I do have one bus with dual carbs, I generally gravitate towards 1974-1979 buses with Fuel Injection only (and standard transmissions).   But as parts get more and more difficult to find (i.e. gold-plated Cold Start Valves.......I say they are gold plated because I believe they must be based on the prices being demanded for them lately) and way more complicated parts, pieces and many sections of fuel lines, I'm starting to wonder if in fact it's not such a bad idea to replace all that gear and worn out parts with a single progressive carburetor (and it's related parts that replace the FI pieces). 

It does not seem all that expensive for the entire conversion kit/carb from places like CIP1 (the EMPI carburetor) or from other suppliers in the US that provide actual Weber kits.   I guess you need to also change the fuel pump (not certain on that though).  Assuming I can learn how to tune up a carburetor, this sure seems a possible way to go instead of dealing with all the failing aged parts with all their vacuum controlled diaphrams, cold start valves, the amazing AFM, the thermo-time do-jigger, the computer, the many sections of fuel line, etc, etc. 

Anyone out there done this and like or dislike their results?   Just wondering what the downsides are?   Is there a loss of horsepower?    I'm curious to hear opinions, especially if you have done it or have a bus running with this setup.

Thanks!
-George
1975 Westy, Serenity
1975 Westy, Jack Sparrow
1979 Kombi, Pistachio
1979 Kombi, Oliver
1977 Tin top camper, Cosmos
1974 Westy, Garfield
1973 Tin top camper, Bart (now thinking he's 1976)
1974 gutted Riviera, Casper
1975 Westy, Stella
1979 Super Beetle, Penelope
1967 Fastback, Green Hornet

Offline BUSDADDY

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George, give your head a shake, a centermount progressive is absolutely the worst possible choice for induction on a flat 4 aircooled motor. The long intake runners aren't heated so they condense the fuel out of the fuel/air mixture on the way to the cylinders, liquid gas doesn't burn so you have to jet much richer than it really needs to maintain a burnable mixture, the liquid fuel just passes through the cylinders washing away the lube on the cylinder walls in the process. The result is terrible gas milage and premature engine wear. They also don't run well out of the box, you'll need to try a few jet changes before you even come close to the performance you get with the FI, count on spending an extra hundred or more on jets and farting around. There's also the issue of the way they behave in cool wet weather, count on engineering some sort of serious preheat for the aircleaner unless you enjoy stalling and hesitation. Great choice for a sandrail that runs full throttle in the hot desert, or an inept flipper who is too lazy or stupid to fix the FI and wants it to run good enough to sell, but friends don't let friends install a Progressive, it's like whacking your thumb with a hammer on purpose.
If you are bent on carbs spend the extra bucks for a set of duals, or better yet OG 72-74 Solex's, the extra cost will cancel out after a few tanks of gas and it'll run much better even though you'll likely still have to play with jetting.

That FI system put up with 40+ years of neglect before it started to act up, it'll cost less to fix it right and then it's ready for another 40 years, it's perfectly tuned for your engine right now and works flawlessly in any weather, if you don't understand carbs stick with the FI unless you are ready for a steep painful learning curve.
All parts are still available for L-jet, AFM's can be rebuilt, new harnesses made, injectors cleaned or replaced, and GeeBee makes all the oddball hoses. Dozens of other makes use L-jet as well so things like that CSV are also found on Nissan/Datsun, Isuzu, BMW, Lotus, etc..., whatever it costs you will be much less than new carbs and the time to set them up well. There's also the option of just deleting the CSV, it's not needed above ~0*C on a healthy engine.
RUST NEVER SLEEPS

Offline Brenticon

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Offline kinggeorge13

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For now I've ordered the cold start valve I need.   As I wrote on my post, I do gravitate towards FI bus engine setups as I understand them and pretty much understand most of their parts and how they function together as I've learned bit by bit by working on them and reading a lot.   I've done zero work on carburetors and they are a magical mystery to me and if I can survive my life with buses without ever having to go there, I'll be a happy guy.    Several people during past conversations have asked me why I prefer FI over carbs and other than understanding them, it also seems to me that they just run and it seems to take a lot of things failing before they stop running.   My experience, as limited as it may be, with my buses is that all of the FI engines I've had so far have been modified in some significant way with various valves that were once controlled by a vacuum either being capped off, removed or in some cases, bizarrely rerouted and yet they all continue to run.  Maybe not to factory specs but they do run and from what I can tell most of the modifications were done a good long time ago.   Someone should write a book (or a blog) on all the modifications they've seen done to these FI systems (and why each one was done or a best-guess at why) and how it likely affects the engine performance.    Yes, I realise several of those components were for emissions control so blocking them off and/or removing likely had no deleterious effect on the engine running (although I managed to tune mine up enough to at least pass AirCare each time back in those fun days).   

Anyways, I'm rambling on and my general feeling is I will remain true to the FI systems as long as possible, particularly as long as I can find parts.

Oh yeah, speaking of parts, Dubs in the Barn in less than 48 hours.   I'm pumped!!!!!   

-George
1975 Westy, Serenity
1975 Westy, Jack Sparrow
1979 Kombi, Pistachio
1979 Kombi, Oliver
1977 Tin top camper, Cosmos
1974 Westy, Garfield
1973 Tin top camper, Bart (now thinking he's 1976)
1974 gutted Riviera, Casper
1975 Westy, Stella
1979 Super Beetle, Penelope
1967 Fastback, Green Hornet

 

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