914 carb size vs performance vs mpg

[steve rush]

The gal and I take lots of long trips and I was curious what difference was between a pair of single 34's, dual 36's, 40's, 44's gave in relation to performance and cost in mpg?
thanks

[Jack Stands]

None of the carb setups are going to give you as good mileage as the original fuel injection.

Assuming you still have the original cam, I'd recommend either the 36 or 40mm dual carbs. 44s are too big for a street engine. Also, is the engine a1.7, 1.8, 2.0, or some other displacement? A lot of factors come into play.

[steve rush]

Had a TON of family stuff and just now able to stand in my garage again.
If you have time would you steer me a bit on assembly of various....
The motor is a 2.0 and I don't have any of the F I only a few different sets of carbs.
I have a set of 40's and a pair of the singles off a 1.7...linkage, manifolds, and air cleaners.
Just want to drive and decent mpg....don't want to get out and push on a freeway onramp.
Oh do I want to change cam?
tks your time, Steve

[Joe Ricard]

Most ecomonical is the 40 IDF with 36mm venturi Why? because that is probably what you have already. Buying new carbs and tearing engine down to change cam is a big deal money wise.

Jet it properly keep them in synch and you will have decent performance and MPG. More MPG = less performance.. More Performance ??? yea less MPG.

[steve rush]

JR thanks...am pulling motor apart as has not run in 15 years...and wanted to
put the right cam in anyway.

[TheCabinetmaker]

research all the parts, decide on Cam, valve sizes, bore, stroke carbs all before you start to buy parts. treat it as one big package, design the engine to work with a certain set of carbs. work with an engine builder if you don't have experience in this. an experienced builder can help you select the right parts, every thing must work together for optimal use

don't forget to include exhaust system and gearing ratio (include tire size) when designing the motor package.

[steve rush]

Cab, tks...is there just a mild 'plus' cam for carbs? Or a quality outlet...reminds me I didn't check PP

[Dave at Pelican Parts]

We can get a number of Web cams. You can see more details on them on Web Cam's own page, though, Web Cam Inc. - Performance and Racing Camshafts .

Lots of other grinds are possible, though, and they can have a very strong effect on the way the car runs and where the power band lies, and so on. Most of the people who have developed their own grinds prize that information very highly, and it usually costs a whole lot of $$ to get detailed information from them. It often involves buying the cam, lifters, valves, springs, and maybe heads from them...

Or you can use one of the off-the-shelf types.

--DD

[steve rush]

Dave thanks...I own one of the 'off the shelf' wallets
will see what web has for the ordinary driver guy.
A old drag race buddy said there is ignition that sort of sputters
his way of saying a sort of continuous spark that he likes...he runs
drag bikes...
That sound like any that would work on a type 4 ?
best, Steve

[Dave at Pelican Parts]

Sounds like he means an MSD--Multi-Spark Discharge system. Made by MSD and a few others. At lower RPMs, it will fire the spark plugs more than once during the power stroke. This is supposed to make sure that the charge gets nicely lit, and according to some schools of thought will help keep the plugs a little cleaner.

At higher RPMs, there isn't time to light off the spark multiple times.

--DD

[steve rush]

msd, tks dave

[porschetub]

Originally Posted by steve rush

msd, tks dave

You never really get great economy with carbs but no one can say the EFI set-up is really that great for the size of the motor...but @ the time it was very good and very clever when you compared others cars of the time.
The "good" kadrons or 35mm Solex's are a good start for economy and provide a good power curve but really need to be set up dead right,way better than the non USA stock/bus carbs,hard to find a sweet spot with them.
The larger 2 barrel carbs are a real change in power but need to be set-up right otherwise no real power increase over the 1 barrel carbs .
If you are opening the case a cam change will help a lot,yep Webcam and don't forget Fat Performance they have been around for a bit also.

[steve rush]

Hey downunder thanks for info. Is it a 'hands on' tune as you go or a math situation where you enter displ, carb size, then jets etc? Sort of look for the old german guy or a solex chart?

[porschetub]

Originally Posted by steve rush

Hey downunder thanks for info. Is it a 'hands on' tune as you go or a math situation where you enter displ, carb size, then jets etc? Sort of look for the old german guy or a solex chart?

The tables/charts/books you can read are good for a ballpark setup and your engine will normally run fairly well,most carbs supplied in a kit will likely be in that range also but rarely "dead right out the box'',it no one size fits all here.
Some kits are known to have incorrect idle jets ,these little suckers are very important for even smooth running in the majority of your street driving rpm,I personally have changed more of these than main jets.
Aircoolednet have a great tech article which gives good insight to the the basics and common jet specs for carbs used on vw engines.
Give your old kit a good clean up,(rebuild parts kits aren't expensive) ,make sure your linkage assembly is reuseable and works freely,set your air bleeds and throttle stops off the car ,run new fuel lines and use a good filter and ensure you have the correct pump set-up before you refit the engine,this will save time bent over the car.
Poor economy can be directly linked to jetting but can also be caused by incorrect setup to start with,the carbs must work accurately together ....even vacuum and linkage setting are very important for example,good luck.

[steve rush]

Hi and thanks, a little brighter each day.
Is there a way of entering cam profile and back pressure...muffler style?
best, Steve