carbs

[77westydad]

building a 1955mm bus motor, engle w120 cam, 90.5 stroker piston and jug set, stroker rods, 76mm c/w crank, no case clearance needed but was checked. this is being put togather with a lightened flywheel and I weighted front pulley. top this off with a set of 041 big valve heads and heavy lift single wound valve springs, the question is how much carb or dual carbs do I need to feed it . may a rough HP output as well as torque. any pro builder have and thoughts on this

[Marc]

I would've used dual springs with a W120 but you may get away with it in a Bus. But then I would've chosen a W110
Those stroker rods saved you a lot of work, I used some Chinese 5.5" I-beams with the 76mm crank in my trike's engine and the case needed significant clearancing.
I'd probably go with 40mm carbs (DCNF or IDF Webers) for a Bus. Kadrons would work and be cheaper but you'd be giving up more of the top end which that cam/heads are capable of.
Never been a big fan of single center-mount carbs unless nothing else will fit, and aircleaner clearance would be at a premium with many. But if you wanted the simplicity, a 44DCNF could work.
You're probably somewhere in the 75-100 honest flywheel HP range depending upon carb choice. Torque & HP are always identical @5252 RPM, which is probably the highest you'll be taking it. It'd only be a guess to narrow it down any further; weigh the vehicle and get a couple of quarter-mile timeslips, then use one of the many online calculators to estimate the HP.

[ainokea]

I too am running a 1956cc engine in my bug built in 2007, it's pretty close to what you're running. 76mm chromoly crank, 5.4 chromoly rods, no clearence needed. Heads with 40mm int & 35.5 ex. stainless valves with single hi rev springs. Mahle 90.5mm stroker pistons & cylinders, 28mm lifters, and Engle 130 with 1.25 rockers. I know, to much cam, however no cam related problems. Distribution is handled by a Pertronix ign. module in a Bosch 019 and 40K Flamethrower coil. Carburetion is Weber 44IDF's but needed to go down to 34mm venturis and .57 idle jets to get the best results. I did try 40IDF's but was not particularly happy with them up top even with 30mm venturis. a 12 lb. moly flywheel and a stock 200mm bus clutch rounds it out. Lousy mileage in town but 24 mpg's on long trips as well as plenty of passing power.

[Marc]

I tried 44IDFs on a 1775 in a baywindow and could not choke them down far enough to provide decent low-end response - ended up swapping them for 40IDFs with 28mm vents. With the longer stroke I can see where 44IDFs could be made to work, but I suppose to choose between them you'd need to consider your gearing (mine was early 002), vehicle weight, and of course what type of power you'll be happiest with - low end torque/smooth response or windbreaking HP on the highway. With the same gearbox and slightly taller tires, an 88x82 1995 worked well all-around with 48IDAs (36mm vents). It only had a W100 but could do 100 MPH, and with a stock-weight flywheel First gear was rarely needed. But 20 MPG was the best it could do on a good day...

[Ol'fogasaurus]

I run 40 Dels on a 1775 that has an RV cam (high lift but a short duration. Built for torque). The carbs were jetted for the engine size and it runs quite nicely. I agree with the 44's with a stroker crank.

[sideshow]

Bus? Smaller cam, the 120 is more of a light weight vehicle application.
In all instances of an wide engine compartment, dual 40 IDFs or the dual Kadrons. Idfs are better, but they have more parts and adjustment. Kads are better in that they have less parts and adjustments.
Singles are tough to get great drive-ability but fit narrow enclosed engine compartments better.

[ainokea]

You might wanna' check out CB Performance for some shorter manifolds that could give you the clearance needed to run 44's or just more room for your 40's.

[Marc]

You might wanna' check out CB Performance for some shorter manifolds that could give you the clearance needed to run 44's or just more room for your 40's.

? IDF series external dimensions are essentially all the same. Side clearance is more than ample in a Bus engine room anyway.

[ainokea]

Yes, I know the 44's have fixed dimensions, but there are manifolds that are shorter, not the carburetors, the suggestion was to check out CB Performance for shorter manifolds.