If I was getting a 1600 Twin Port rebuilt, there would be a standard cost to built a stock engine. If I wanted to introduce just a little bit more power, what could I do without introducing a domino effect of modifying everything. 20-30% extra power would be great if it didn't mean buying a massive expensive number of extras.

The motor currently ticks like a Swiss watch, and everything runs perfectly, it is just tired. Carby is perfect, exhaust is German, including German tips. Distributor is great. Like I said the motor runs well, but is showing it's age.

Thoughts and opinions?

Stock crank
Stock rods
90.5 or 92mm pistons and barrels?
Stock heads ported a little
Engle 100 camshaft
1.1 or 1.25 rockers?
Stick with the PICT 34 carb or go for a progressive two barrel?
Stock exhaust
Stock distributor with advance spring modified by professional ignition guru.

The exhaust and carby are the two most restrictive parts of the engine and hence the lowest-hanging fruit in terms of power increases! If you have a stock setup in nice condition and want to keep it then I suppose you could make small gains by fitting a big bore kit and so forth but really the carb and exhaust are already too small for the stock engine to make maximum power.

First thoughts for me to is to go displacement. 1776 (or more) stock heads with a performance valve job and cleaned up ports, low comp, unshrouded valves, stockish cam swivel feet and maybe shimmed rockers if you wanted to go all out. Of course balanced with head and decks set up goes without saying.

Many years ago, a mad Volksie dude I knew had a 2180 running a 34PICT and peashooter exhaust. He built it for torque to pull his tinny up the local boatramp. Hell, that thing could fry the 165's off the rims, but only to about 4000 RPM, then it was like a rev limiter cut in

Next step up maybe?
Progressive two barrel carby
High flow heater boxes with suitable exhaust.

As soon as you free up the exhaust, I'd go for Dual IDF's and a 4-1 exhaust. Bigger heater box's only if bigger valve heads, and now your opening up a minefield of options.

You originally said 20-30% increase in power, that is easy, valve job, chambers, 1776, properly built.

40-60%, IDF's 40x35 ported heads mild cam, 4-1........

Thanks Matt. I see there is a line. I am trying to stay on the stock but more powerful side. The other side has no end, and has the minefield.

The torque to 4000rpm sounds good. I am just looking for smooth low torque and power to get a move on, not race around a track.

I can always change the carb setup later.

Any opinions on progressive two barrel compared to twins?

they love the juice, you can nearly watch the needle go down. id go the twins if it was me. but if your set on the prog make sure you use the premium redline manifold that has the heated air chamber surrounding the manifold.
are we talking vacuum secondary or mechanical on the prog?

I really prefer stock or duals, Kaddies are ok, but I prefer for a real mild engine, 36IDF's and 4-1. Marcus has one in his boss' bus. 1641, 40x35 ported and chambers done, stock cam and it is a real favorite. A joy to drive, in a camper too.

And x2 on ^^^

No replacement for displacement eh?

Clean efficient power with more cc

some ideas here

http://www.aircooled.net/gnrlsite/resource/articles/mods.htm 

For an inner city daily you don't wanna go too silly, one because you just don't need that much power and two the fuel economy goes out the window.

Me who is a Larry lead foot was quite happy with the performance and economy of a bog stock 1600 twinport with a 4into1 header and quiet pack and a 40mm twin throat Weber DCN with electric manifold heat. Later swapped for type3 twin carbs then Kadrons.

DCN and type3 carbs were averaging 9-10L/100km in a heavy Lbug, K-dogs were abit more thirsty but gave bit more grunt too.

Carb and exhaust like Waveman said really wake up a stock engine.
But forget progressive, good for a door stop, go twins over a single.

You can keep the 1600 displacement and "perk" things up a bit, a pair of carbs as mentioned before, say ict's, 36idf's, will give it a jump, clean up the heads, and flycut for a bump in compression up to 8:1 new rings etc. The biggest jump in performance I've felt was going to a true merged header, and dual 40idf carbs

This is a good thread as I'm looking into breathing a bit more life into a crapped out 1600 for my bug. I've been told that a twin carb set up is the best way to go too. One of my current problems is a blocked manifold preheat and I am looking forward to kissing that good bye.

I acquired a 1600 with no known history. Pulled the heads and lapped the valves. Put it back together (it had a couple of loose/broken head studs), installed a 009, 4 into 1 merged extractors and a holley bugspray. Not the best carb but bigger than stock and I already had it. It went like a ripper for many years. Later on I bought a second hand set of 1.4 : 1 ratio rockers and that added enough extra power that you noticed it.
Great set up for little cost. Way better than stock, not hot enough to break anything.

When you say 4 into 1 merged extractors, are they compatible with the original heat exchangers?