VW Flat fours. Time to dig out the Porsche type thingy - PeachParts Mercedes-Benz Forum

pentoman · #1 09-04-2003, 09:43 PM

Ahh, sunny weather is here and it's time to dig out the Porsche replica thingy. Needs some work (fitting seatbelts would be nice) and has knocked up a whole 170 Km in its lifetime.

I post this because I'm wondering, does anyone have much experience with VW flat-fours?

This has one, and all I know is it has a twin-choke Weber 44 IDF, and is very, very loud. It will rev off the clock if you like (so over 6000 rpm) but pulls well from 2500-3000 rpm up, though I guess it would as it's so light (1450-1500 lbs). Oh yes it has Autokraft rocker-roller bits.

It has a small issue - throttle response is good on light throttle, but if you give it lots of throttle, it 'goes wuuuuurrrrrrrr' and loses power for a second or maybe more, then starts to pull really hard. It sounds like it's sucking plenty of air in when you do it, I guess it's not getting the fuel to go with it at first. I am told, and am inclined to believe, it's probably a slighty clogged carb. It doesn't feel ignition related and I'm pretty sure it's not.

That's all I know about the engine. Any ideas as to it's power, or any other interesting (lengthy, if you like) tidbits about VW four's in general?

As you can tell, I was born quite some time after they came about...

Jim Anderson · #2 09-05-2003, 10:28 AM

It sounds like your fuel pump isn't up to snuff, or an old fuel filter.

VW flat 4's: Check the valve adjustment. The alternator provides cooling, keep that in mind if you lose the belt.

rickg · #3 09-05-2003, 11:13 AM

Do you have air filters on the carbs? A strange thing I learned in my days of messing with VW's with dual carbs is they won't run worth squat without an air filter. With the short intake runners you actually get an interrupted pulse thru the carb, which causes a momentary backwards flow of fuel/air. An air filter housing contains this pulse, which then gets pulled back thru the carb on the next intake stroke. Without an airfilter, the air/fuel gets dispersed, and the engine actually will run lean, and run like crap.
Sounds crazy, but I had a heck of a time getting an old VW squareback to run right. I got frustrated with the F.I. that worked only when it felt like it. So I yanked it all off, and put on dual carbs. I had to do alot of research before I came across this tidbit. I made some airfilters that would fit under the engine cover, and prest-o! She ran great, and adjusting the carbs actually made a diff.

pentoman · #4 09-05-2003, 03:21 PM

Quote:

Originally posted by rickg
Do you have air filters on the carbs? A strange thing I learned in my days of messing with VW's with dual carbs is they won't run worth squat without an air filter.

Funnily enough, no I don't. The bonnet/hood/back of car only closes without it on, which is another problem to look into. Any fix to this? Can you get buy cleaners which don't stick up an extra 3 inches off the top of the engine?! Maybe you'll have to make me some eh? :p

Jim - Thanks for the note on cooling - I wonder about it on hot days, but it's nice and simple to know there's no radiators or water pump to worry about. Where's the fuel filter. When I first ran it after ~8 years of sitting, it would run for only a minute at a time. Turned out to be solid dirt in the fuel tank, which I pressure washed out. Also after sitting for a year, it takes a good 2-3 minutes of turning over before any fuel arrives at the carb. It has one mechanical fuel pump on the engine and that's it.

Paul, yes indeed - I believe it's an early Beck Spyder, imported here from Brazil about 10-12 years ago and never used. It will eventually be fully roadworthy and can go to its real owner who imported it all that time ago.

thanks

Russ

G-Benz · #5 09-05-2003, 03:36 PM

What you haven't shared is the displacement and configuration of the motor.

Is it a Type I single or dual-port setup. 1500, 1600 cc, or Type 4 (1800) or bored out?

I didn't catch if you were running duals or not...44IDFs are WAY too big for a stock displacement motor. If you are running a single carb, consider a smaller jet. You may be bogging down.

Also what kind of intakes are you using, aluminum, steel, or other? The early steel intakes had pinhole leaks that caused all sorts of vacuum problems.

As far as air cleaners, check out the VW mags...plenty of places that advertise have all sorts of short air cleaners that will fit your application. Its a bit tougher when you have a dual-throat unit like yours.

My Super Beetle is a 1641cc and I run dual 34ICT Webers...

rickg · #6 09-05-2003, 03:58 PM

I wasn't worried about asthetics on my old squareback. There's no room in those cars either for much of an airfilter. I just bought a couple replacment filter elements for those cheep-o Cal-Custom airfilters. Then I went to the hardware store and looked thru the PVC fittings in the plumbing dept and fab'd some. Looked dorky as heck, but worked great

Hey G-, have you ever posted any pix of your SuperBug here? Would love to see more of it to inspire me to get back to work on my '71

G-Benz · #7 09-05-2003, 04:21 PM

I've got tons of pics (from my car show era 86-97) but only one digi pic...sorry

The weather has ravaged the paint and interior badly, and I too, need inspiration to ressurect it to its former glory!

Perhaps when my daughter gets a little older, we'll wrench on it together...it'll be like Paul Sr. and Pauli at the Orange County Chopper shop on "American Chopper"... :p

pentoman · #8 09-07-2003, 09:02 PM

Quote:

Originally posted by G-Benz
What you haven't shared is the displacement and configuration of the motor.

Is it a Type I single or dual-port setup. 1500, 1600 cc, or Type 4 (1800) or bored out?

Hmm, haven't a clue..

Quote:

I didn't catch if you were running duals or not...44IDFs are WAY too big for a stock displacement motor. If you are running a single carb, consider a smaller jet. You may be bogging down.

Also what kind of intakes are you using, aluminum, steel, or other? The early steel intakes had pinhole leaks that caused all sorts of vacuum problems.

Still no clue.

I do know the engine was installed, new, by a fairly professional outfit who specialise in aircooled VWs, and has one single, twin-choke 44IDF, so I suspect the 44IDF matches the rest of the spec... whatever that may be?! What sort of cc's is it usually matched to? Intakes I'm not sure either.

The whole engine was a fairly expensive brand new professionally installed item, with a custom exhaust designed with the correct lengths and installed, so i'm fairly sure the bits on there all match up and are as they should be.. apart from the 10 years sitting unused has upset something slightly.

N.B. mixture adjustment was done on an emissions tester not so long ago

Quote:

As far as air cleaners, check out the VW mags...plenty of places that advertise have all sorts of short air cleaners that will fit your application. Its a bit tougher when you have a dual-throat unit like yours.

Oddly, the car has an air cleaner as supplied with the engine, but it was never installed because the back won't close then. I tried it with it on and the back strapped down, and it didn't seem very different.. maybe a little

The bog down is only there on the transition from light to heavy throttle. Once in either 'mode', it performs very well.

I thought it may be accelerator pump jets, but they seem to squirt loads of fuel..

G- Like the bug!! Resurrect it!

G-Benz · #9 09-08-2003, 12:13 PM

With a single 44IDF, you are probably using an aluminum or cast intake...no problem there.

See if you can find a Weber supplier for the Type 4 engine. The VW Fastback and Squareback versions had the engine mounted under the rear compartment, so the air cleaners had to be low profile.

As far as engine displacement, probably stock 1600cc (1585 according to VW), although with a 44IDF you could probably run a 1641, 1776, 1835 or 1920cc engine.

I would check the ignition coil. Mine would run flat and eventually eat the coil for lunch (actually, several) until I got the Bosch Blue coil.

You may also have a vacuum advance problem if you are using the stock distributor...if you don't know see if any hoses emanate from the distributor...actually the round thingy attached to the right side of the distributor.

If you have neither...you have a Bosch .009. It a centrifugal advance versus vacuum advance style.

You should be running copper Bosch plugs as well. The platinums don't work well with the air-cooled VW motors nor early MBs...

Take a pic of the motor...I can tell a lot from a good pic...