So, I just purchased a 1975 914, with a 1.7 liter form a 1971 914. It was converted to a single carb, but it misses and stutters A LOT. When it warms up for quite a while, it runs better, but not great. The lower plenum of the carb is ice cold, and I think this may have something to do with it. Any suggestions on what I can look for to resolve this issue?

Get rid of the single carb and put in the 1.7 D-jet... here's one for sale:

1.7 Djet for sale

But fair warning
Installation is not for the faint of heart

Its a common issue with a centre mounted carb,on a type 1 engine you get heat from a heat riser that keeps the manifold pipes from getting too cold,no such solution is there for the type 4,I would expect your car would run better in warmer weather.
Only way to sort this is to get some heat to the centre section under the carb...not a really easy thing to do.

914 motors were not designed for a single carb set-up. Either re-install the D-Jet or get dual carbs that match your cam.

Konrad

My single WEBER Progressive 32/36 2 barrel on my '74 1.8 engine runs great.
It has an Electric Choke and starts every time regardless of Low temperatures. I had some problems that were resolved after the engine had a total mechanical rebuild by a professional Porsche Shop (Translog GT). Tony the shop Owner and Master Mechanic replaced the Cam, with a Cam specific for Carbs. The carb cam works with either Single or Dual Carb set ups. He says you need to know how to tune the Carb not just the Jets and one mistake a lot of people make is not addressing the Float. The Float has to be adjusted for optimum performance to make Carbs work right.

I'd agree that while the single carb isn't the best, it can be set up to work fairly well.

I'm going to guess (from the comfort of my home, without touching your car) that the carb is gunked up and not set up properly. However the symptoms you've got can also be ignition.

Start off by checking the easy stuff, ignition timing and components. Then move on to the fuel system.

Your carb may respond to getting cleaned and a gasket kit. We used to call this "carb rebuild" but there's more to rebuilding a carb than cleaning and new gaskets. To paraphrase struckn, there's no substitute for proper set up.

Typical problems with the single carb is hard cold starting, and a bog or stumble when accelerating from low rpm's. The stumble can be difficult to completely eliminate, the only thing I've seen that helps is an intake with smaller runners, and I've only seen one of those before.

While injection is a much better solution, it's only going to work right if you know for sure the engine has a FI cam, if the cam was ever changed you could get into a major tail chaser.

With all the unknowns, I'd opt to spend as few dollars as possible to get the single carb running right, and if that doesn't work get dual (not duel) carbs. You really don't want dueling carbs, I know that for a fact.

Perry you made some great points and good info for the OP,they really aren't that bad but have an unwanted rep cause they aren't set up right even out of the box or have other issues such as wrong dizzy,fuel pressue,bad ignition,or other engine mechanical issues.
I have never run one but know people that have to good result due to tuning them properly,I don't like the 009 on any T4,curve is all wrong and would be made worse in a centre mount application,however a 034 vacuum dizzy or the current SVDA (?) with a good pointless system would go a long to getting a good running engine.
I have a half completed T4 1.8 bus motor I have been slowly reconditioning and have the manifold runners for this carb and a 034 converted to hotspark,keen to prove the knockers of this system wrong...maybe maybe not,who knows.

First of all,



About the 1.7L with single carb; as some have pointed out, the single carb is not very good with the T4. Dual carbs would be better.

However, the 1.7L is very weak. There are slower cars than yours on the highway although I'm at a loss at the moment to name one.

I started out with a '71 with 1.7L engine with single carb. Cleaned the carb and tuned the engine and it ran ok. Still no power.

Finally I swapped out the 1.7L for a 2056cc T4. I picked up the 2056 used with dual carbs for less than $1k. Added SSHE's and Bursch muffler and now I have a car which is much more funner than the 1.7L.

My suggestion to you is clean the carb, tune the engine and get it running as well as possible. Then look for a 2L or 2056 or larger engine to replace your boat anchor masquerading as an engine.

I'm old enough to remember when the 32/36 single carb was first in use probably 40 years ago.It was used as an aftermarket carb for 2002 BMWs and racing F Fords. When they shipped it years ago they included an optional idle jet. The instructions said on larger than 1600 CC use the larger jet. I can't remember the size off hand and I'm out of town now and can't check my box of 32/36 parts. This usually fixes the off idle stumbling problem . One other "trick" I use when installing this set-up is to use steel head to manifold gaskets, as this will transfer heat from the heads to the manifold. I find some people install the thick plastic gaskets that are used with FI .They keep the heat away from the intake on purpose . If you remove the intake manifolds, be sure to file the mating surfaces flat and true as most are warped with age. One more point ...the choke is electrically heated , be sure it is wired to 12 volt (wire to the + coil lead) adjust properly .