Carburetor Choice

[monkslayer]

Hi Guys

I have a 1600SP VW engine that I am rebuilding,I currently have a 31 Pict 3 but its time is just about up.My engine is purely stock and will remain that way.However I am looking for better performance and better mileage than my current carb setup.In light of this,I finally decided to switch to the dual carb setup.

There are two setups which interest me from CB Performance:

They are Dual Weber 34mm ICT Kit - Single Port Type-1 & 2 to '71 and Solex Carbs - Dual 34mm with Electric Chokes (single port).

http://www.cbperformance.com/ProductDet ... tCode=3284

and

http://www.cbperformance.com/ProductDet ... tCode=6427


Please advise me which between the two is ideal for me with the following in mind:

Easier Installation and maintenance(have to import most parts to my country)
Better mileage,
More Horsepower
Better cold starts
Durability
Build quality
Price vs Performance

If you had to pick one for me which would would it be and why?I thank you in advance for your support.

[Marc]

I've never run those Solex 34s before. It rarely gets cold enough around here for chokes to be needed but I can see where they'd have appeal where it does...and they are cheaper
I've long been a fan of the 34ICT Webers though, once set up they just work, with great driveability and typically better fuel economy than a stock 1-bbl.
Linkage design can be a big factor - I quit screwing around with center-pull and cross-bar setups long ago and use Berg linkage on everything (it's a simple enough operation to make your own down-rods from hardware store bar stock with a ¼-28 die) so I can't speak to how well the CBPerformance stuff works.

...EMPI has ICT knockoffs made in China which seem to be working well for some folks (there were porosity problems in some of the early castings but supposedly that's been remedied). They call them 34EPC and they go for about 20% less than the genuine Webers.
http://www.thesamba.com/vw/forum/viewtopic.php?t=379387

[monkslayer]

Thanks Marc.Seems that is the consensus with everyone!Everyone seems to say the Weber is a better bet...sadly however at the same time very few have actually used the Solex as you also pointed out!

The Solex are USD 100 cheaper thus was hoping for some positive vibe about them.I guess it is a case of you get what you pay for.

[Marc]

I've run Solex 35PDSIs (they were stock carbs on some old Opels c1968-1971) but only in racing applications, with no balance tube. Presumably they'd work OK on the street, I've just never gotten around to trying them. Base flange is the same size as 32PDSIT, so you can use stock Type III manifolds...as with any such cross-marque application, you can expect to have to do some linkage/lever modification on junkyard carbs. Rebuild kits are still readily available for them.

A while back SCAT introduced them in a kit for VWs, in both the PDSI chokeless and PDSIT electric-choke version. They came with tall aluminum manifolds (but I don't think they offered a SP setup)




Here's a second-hand set of PDSIs, but the ad's over two years old...shows the throttle levers pretty well though: http://forums.vwvortex.com/showthread.p ... ne-filters

[monkslayer]

Interesting read.I think I will go for the webers as you earlier indicated.Based on the reviews I am swayed in the Webers direction.

[helowrench]

If you are rebuilding that 1600DP, you will definitely wish to change the cam, and correspondingly, the compression ratio. Allows better function of the total package.

What kind of vehicle?

[Marc]

Near as I can figure, monkslayer has a Euro-spec `67 Beetle. If it left the factory with a 1500, the R&P should be 4.125 - but the available 1200 & 1300cc models had 4.375.
Return on investment for a cam swap with stock-valve singleport heads isn't impressive; it's pointless IMO to put in anything designed for a powerband exceeding ~5000 RPM (even with dual carbs). Something like the Bugpack 4061-10 might be worth it (234° adv dur, .396" lift w/1.1 rockers) and will work with a stock valvetrain. I'd recommend some new stock 1600 valvesprings (shimmed up slightly, say .060" int/.045" exh). Stock adjusters still work at this lift and keep the weight down so stock springs/pushrods/etc. are enough, but a little extra attention to rockerarm geometry may be needed. If shorter pushrods are required, look for the ones from a 1300SP or an early 1500 Bus.
But the difference in power will be small (say, 2 HP...maybe 3 or 4 if you also bump the C.R. up to >8½:1 => Premium-fuel territory). Enough to notice, but not huge.
If you want to be able to burn cheap gas with no worries and stick with the stock cam, you can bring the C.R. up a little for a small improvement in efficiency but I wouldn't go over 7¾:1.

[monkslayer]

It is a 1600SP and i am plan on keeping it single port.I swapped the gearbox and now i am using a 1970 Variant Gearbox which i presume had the 4.125.Don't want to go all ninja on my engine yet.As pointed out...the more you tinker with,the more you have to keep tinkering with.The carbs are as far as i am willing to go for now.

With sensibility most people report that mileage improves or at worst say stays the same with the webers.Not sure if this is a marketing gimmick!;-)

[Marc]

Believe it. The stock single carb, mounted as it is a foot and a half away from the heads, is a lousy match to a horizontally-opposed engine - it was selected for the sake of simplicity and low production cost. Duals will nearly always deliver better economy and better driveability. I have a stock 1600DP with ICTs in my daily-driver right now and it pulls so smoothly at low RPM that I have to remind myself to downshift to avoid lugging it - and that's with the much-maligned 0 231 178 009 centrifugal-advance distributor.
You may need to change some jet sizes in the ICTs for best economy with a stock singleport but the out-of-the-box setup should be close. Typically you'll get F5 or F78 emulsion tubes; with those I'd expect to need a main around 135-140 (assuming the air corrections are ~160-170). The ICTs use the same screw-in main jets as the DFV & DGV progressives* so they shouldn't be hard to find locally if you find you need some.
Often you'll get 52 idles which are on the lean side...see the procedure at the link below, if the mixture screws have to be backed way out to get a stable idle you'll want to try 55 or 60. They have fewer applications (ICH, DGAV, and the primary only on the DGAS)
As with any dual-carb setup it's critical that you get the throttle linkage mechanically synchronized so that both throttle plates are shut or full-open simultaneously. You may need to bend one or both levers a bit to change the effective length; do this before admitting fuel so that if you need to repeat many times to get it perfect you won't be flooding the engine

http://www.redlineweber.com/html/Tech/3 ... unning.htm


Swingaxle Type IIIs with 1500 or 1600cc engines should have a trans with codeletters "DA"; would be 4.125 R&P. We got only IRS in the USA from `68-up so I'm not certain if that box was still used in `70.

viewtopic.php?f=50&t=99606



*Main jets interchange in: ADF, DARA, DCD, DCN, DCZ, DFAV, DFEV, DFI, DFM, DFV, DGAV, DGEV, DGV, DHSA, DIC, DICA, DIR, DMSA, ICH, ICT...and the 3-bbl IDA.

[monkslayer]

Thanks Marc.At least with all this information I can make an informed decision as it is.Webers it is then.

In addition i am informed that i may need to get HD springs and also change the exhaust for an effecient setup.What do you think Marc?

[Marc]

I see no justification for HD springs, but it wouldn't be a bad idea to replace them with new stockers since they're probably decades old. I recommend using steel shims under the springs for any application to keep the springs from chewing into the head as they rotate (and they will). Typically on used heads the intake valves will be deeper after a valve job, so you could need thicker shims on their springs to restore the spring installed length.
The stock valvespring retainers allow the valve to spin between them - it rarely presents a problem on a completely-stock motor but it's still good practice IMO to sand them down slightly so that there's a small gap between them when in place around the valvestem - that way they'll pinch into it and there'll be less chance of chatter-damage to the lands. You shouldn't really require anything more than stock rockerarm assemblies, but do take them apart for inspection and replace any heavily-worn parts (the "wavy" washers and the spring clips in particular).

The stock muffler provides better intake manifold preheat than just about every aftermarket exhaust system, but with dual carbs you no longer need to worry about that
If you do decide to upgrade, avoid the Monza/Pacesetter style. A "street" 1⅜" 4-into-1 header with a single "Quiet Power" muffler would be an appropriate choice for this engine. Note that almost all headers lack the little heat pockets on #2 & 4 headpipes so the freshair hoses have to be routed around them - expect a little more routine maintenance since the hoses tend to burn up where they contact the pipes. You'll also lose a little ground clearance - steep driveways and speed bumps can be troublesome.
If your stock muffler is still in sound condition, a modest power improvement comes from merely removing the packing from the tailpipes - but it does make the note rather boomy, especially at low RPM, and promote backfires on deceleration. You should still be able to find some of the "taper tips" which were sold at VW dealers years ago; they flare out to a larger diameter but retain the packing so the sound's still fairly mellow.