Wouldn’t it be better to go with a single 2 barrel progressive carburetor than two separate carburetors?
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Depends on what you are wanting the engine to do. If you want user friendly, high mileage low trouble and low maintenance then get a Stock 1600cc VW engine with factory single barrel carb. The trade off is the 60 HP performance. To get better performance from a VW type 1 engine usually takes the addition of carbs mounted directly on top of each head. The long intake runners it takes to run a center mounted weber 2 barrel or the old school Holley 2 barrel "bug Spray" set ups cause poor fuel atomization and intake freeze up in cooler temps. This is a main reason the dual Weber or Dellorto carbs are used. Carbs are in good condition (never buy a set of used carbs cheap unless you want real headaches) and tuned by someone who knows how, are a thing of beauty and run wonderfully and make a healthy Type 1 engine run amazing. The other mistake people make is to install dual Webers on a tired impaired engine with compression differences between cylinders greater than 10 psi. The results magnify the engines issue , the carbs run like sh*% and kill the engine off in quick manner. So the perfect setup for any engine is one carb throat per cylinder with the carb close to the head. Even fuel injection setups for type 1 engines use dual carb like setups to get one throttle body per cylinder. To answer your question, center mounted performance carbs don't work all that well on our type 1 engines and have clearance issues with our Speedster engine compartment lids. The progressive Webers used on Porsche 914's are not so good it is an old carb designed that was designed for the 2300 cc Ford Pinto engine. They make the engine run but the performance loss is huge. I am sure many others on here will have better and possibly conflicting replies. So I end this with this being IMHO.
Thank you for such detail, I remember those Holley carbs, they never did work well. The engine I’m getting is a 1915 cc with Kardons (I’m told they are some kind of Solex) I believe they are single barrels feeding each bank. Are you familiar with this setup? I would prefer Webber’s but at this point I’m deferring to the builder. Any advice or comment would be appreciated. Thank you.
Tons of folks use and love those carbs. Like Danny said, one throat per cylinder is optimal for performance, but 1 throat per bank on short manifolds is the next best thing. On the plus side, they'll probably be easier to keep dialed in than Webers or Dellortos.
My dells were rebuilt by an expert 4 years ago, and I end up fiddling with them about every 500 miles. Just today they started burbling a bit coming out of the mountain, and popped at few times during shifts. I guess they'll be coming off to blow out the passages* and the jets next week. (I can't wait to get rid of this rusty tank. I'm sure that's the problem, despite 2 fuel filters.)
*Thanks to whoever posted that YouTube video. I'll be reviewing it first.
Dual single barrel solex carbs on a smaller displacement engines (under 2000cc) run great when setup correctly. The engine you are having built should have snappy throttle response and good pulling power up to 4500,maybe 5000rpm but the sweet spot on this setup will be zero to 3800 rpm's which will make for a super fun driving car with the torque in the usable range for most sane drivers. You should have many miles of trouble free driving with this. Let us know how it goes.