Can someone explain what the differences are between a 1600 single and twin port motor?

I tried to explain today but made a meal out of it lol, does the twin port have more valves etc?

Thanks in advance

Its just in the intake manifold and head design

this might help

Twin port has a different carby too I'm pretty sure.

Question... does a single port 1600 have a dual-relief case ???

Quite simple

From 2443TT's amazing drag bug thread

A Dual/Twin Port head


And a Single Port head



Im not sure if this is the best explanation but I'll give it a go.
A Dual/Twin port head has a port (or tube) for each intake valve (the 2 valves in the centre, not the out side) and a manifold like in the thrid image across that Joel posted.

A Single port head has only one smaller intake tube/port that 'splits' in 2 for the two middle valves, inside the head.

That first picture (dual port head) from 2443TT's thread is of a very very well modified head, not stock at all (But still works exactly the same)

Hope I didn't confuse you

Cheers!

So a twin port allows better fuel flow to the engine? so what carby would be better suited for a twin port, i think mine just has a standard solex

All air-cooled Volkswagen engines have only eight valves - four intakes and four exhaust valves, one each for each cylinder. There were no 'multivalve' VW heads (until the Golf came along...)

All engines up to 1971, as Lee said, were single port - that is, the 1200, 1300, 1500 and 1600. All had single relief valve cases. The Beetle only used the 1200, 1300 and 1500 engines; the single port 1600 was only used on the Type 3 and the Kombi.

In 1971 the 1600 twin port engine was released, with a twin pressure relief valve case. It was designed for the US market, which had stricter smog laws than the rest of the world. The engine was designed to run leaner and hotter to reduce lower emissions. This engine was used in the Superbug, Type 3 range and the Transporter. Shortly after, a twin-port version of the 1300 engine was also introduced, for the same reasons. These were sold in Australia in the 1300 torsion bar Beetle from 1971 to 1975.

In stock form, a twin-port head only flows marginally more than a single port - remember that stock VW engines aren't designed to rev over 4500 rpm or so. The twin port head does, however, have more scope for performance improvements.

All VW 1200, 1300, 1500 and 1600 engines had single Solex carburettors fitted - only the model type was different. The 1600 twin port engine came with a single 34 PICT/3 carb.

generally it was pict3 carbs that came on twin ports
ie. 31pict3 on 1300tp and 34pict3 on 1600tp

and single ports had earlier ones like the 30pict1/2 etc

but carbys are usually the first thing that get swapped over the years

According to Mick Waldron my car currently has a standard 1300 carby, guess I should try and source a 34 PICT/3

You use a stock distributor with a stock carburettor - 009s are for non-vacuum signal carbs.

Shouldn't be too hard to find a 34PICT/3 as all the 1600 TP engines came with them. Most VW workshops should have boxes of them lying around. Try ringing Boris at Vintage, for a start - he has shelves groaning with boxes of wrecking parts. I also reckon Mosche at Bug Parts Punchbowl has dozens of old filthy ones lying around his workshop...

Ok I checked out the carby and it is a 30PCT, as you can see in the photos an adaptor plate has been fitted to the manifold.

Question is how much performance am I losing with this carby and should I replace it with a 34 as suggested?

you are loosing bugger performance

Many people "upgrade" to a 30PICT

It is a "simpler" carb that works better in many ways

x2

that carb will be alot less finicky than a 34pict3
ive got a spare 1600tp with a 31pict3 carb and the only time i noticed any difference was nailing it when its already at 2500rpm or more, the 34pict3 picks up the pace abit quicker

that carb you have now looks like it needs some attention though
the float gaskets leaking by the looks and the idle screw is almost wound all the way in which means the progression circuit cant do its job properly

probably just needs a good clean out and a new kit put through it

thanks Joel will take a look and will add it too the list of jobs