TheSamba.com :: View topic

Sun Sep 26, 2021 2:24 pm

My wife and I recently purchased a 1978 Super Beetle Convertible, our first VW Bug, so we are just getting into this.
We are studying “The Compleat Idiot”, websites, The Samba, etc…. and trying to get up to speed.

A couple of notes before I ask my questions. The Beetle came with a Fuel Injected engine, but we decided to have it changed out to a 34 PICT 3 carb and the engine is a 1600cc 50hp (48hp).

When we do City driving it drives the Beetle drives okay, but when we hit the Highway it only tops out to maybe 52 to 54mph and bogs down on hills. We were thinking that we should be able to see somewhere between 65-80mph??

Is that realistic?

Any ideas on why we might not being getting full engine power? What should we look at or tweak on trying to improve the engine performance?

I'm doing research as much as I can, but I figured I would just toss it out there to start getting some thoughts and input from you folks.

Any thoughts, comments, and help would be greatly appreciated.

Sun Sep 26, 2021 2:26 pm

Could be a number of things, fuel pressure could be one since you converted from Fuel injection to a carb, did you change the electric fuel pump or add a regulator to lower the pressure?

Your ignition timing could be an issue, I see you posted a topic asking about the distributor.

The carb looks to be new and I assume it's an aftermarket version. The problem could be there.

Sun Sep 26, 2021 3:20 pm

GotBugged wrote:

A couple of notes before I ask my questions. The Beetle came with a Fuel Injected engine, but we decided to have it changed out to a 34 PICT 3 carb and the engine is a 1600cc 50hp (48hp).

Oof you should not have done that.

Sun Sep 26, 2021 3:24 pm

Yeah, not only a downgrade in horsepower, if the new parts came from China it's introduced a whole bunch of extra issues.
I hope you kept the FI components.

Sun Sep 26, 2021 3:38 pm

GotBugged wrote: The Beetle came with a Fuel Injected engine, but we decided to have it changed out to a 34 PICT 3 carb and the engine is a 1600cc 50hp (48hp).

Any thoughts, comments, and help would be greatly appreciated.
My thought are that this was a good idea, and especially if there were any issues at all with the fuel injection system.

GotBugged wrote: When we do City driving it drives the Beetle drives okay, but when we hit the Highway it only tops out to maybe 52 to 54mph and bogs down on hills. We were thinking that we should be able to see somewhere between 65-80mph??

Is that realistic?

Absolutely realistic to get 75 mph on relatively level highway.

GotBugged wrote: when we hit the Highway it only tops out to maybe 52 to 54mph and bogs down on hills.

Any ideas on why we might not being getting full engine power? What should we look at or tweak on trying to improve the engine performance?

I see in your photo an issue with the steel accelerator cable tube that goes through the fan shroud. This might be preventing full opening of the carb on acceleration/full mashing down on pedal.

On my VWs, I add a hose clamp to the forward (hidden) side of the fan shroud to keep that in place, and so the cable can be adjusted correctly.
Your photo

Here's mine, with clamp

And if the timing was set when you still had the hoses connected incorrectly as in your photo, that should also be checked.

Sun Sep 26, 2021 3:54 pm

I think the vacuum advance hose is hooked up to the wrong port on the carb...you may not be getting any advance.

Also, since you don't have heat risers to the manifold, at the very least you should get a factory air cleaner and hook up a heated air hose to it.

Mon Sep 27, 2021 3:21 am

sjbartnik wrote: GotBugged wrote:

A couple of notes before I ask my questions. The Beetle came with a Fuel Injected engine, but we decided to have it changed out to a 34 PICT 3 carb and the engine is a 1600cc 50hp (48hp).

Oof you should not have done that. X2 on that! My F.I. bug easily goes 75 all day. However something is obviously quite wrong

Mon Sep 27, 2021 3:24 am

I would definately check timing. Forget setting it at idle...the real important setting is max advance. Set for 30 degrees at 3200 to 3500 rpm. Also if the advance hose is on the wrong port it won't affect highway driving under load, that would fall to the mechanical advance part of the distributor. What did you do with the fuel injection system?

Mon Sep 27, 2021 4:53 am

I have converted my FI engine to carb as my FI was shot and i live in the UK and parts are not easy to get.

I did use genuine 34 pict-3 carb and correct distributor to match as ssaid you have no pre- heat what exhaust are you using?

You have double vac distributor with only one vac connected im not sure if thats a good thing

Also on an FI fan shroud the accel cable is in a different position so you might not be getting full throttle

i can get 80mph from my engine no problem

Mon Sep 27, 2021 6:07 am

Have you tested the distributor to make sure it actually advances properly? How much pressure is your fuel pump putting out? Can you tell us what was wrong with the fuel injection system that prompted the conversion to a carburetor?

You will need manifold heat up in Massachusettes. It is already cool enough there to freeze up the carb/manifold.

The proper solution to your problem would have been to come here for advice BEFORE changing a bunch of stuff.

Mon Sep 27, 2021 7:25 am

I think i would be taking it back to the person who did the conversion and ask them to do it correctly, unless this is something that you have agreed to prior the work and he has explained that you do not have correct fuel pump, exhaust, carb and manifold, distributor also air filter .

Mon Sep 27, 2021 9:26 am

No heat risers=Icing manifold. That variable alone could explain your performance issues. But there are likely other issues here too as stated in the replies.

Pull over when it starts to bog down and feel the intake manifold
Under the carb. I’ll bet you it is ice cold, and may even have ice on the outside. Fuel is condensing to liquid in there. Liquid fuel will not combust.

Mon Sep 27, 2021 12:26 pm

You might consider this for winter driving -

https://www2.cip1.com/c21-2139/

Tue Sep 28, 2021 9:20 pm

Make sure its getting full throttle when you put the pedal to the floor.

Wed Sep 29, 2021 7:43 am

johnnyvw164 wrote: I think the vacuum advance hose is hooked up to the wrong port on the carb...you may not be getting any advance.
*** THIS ***

Max

Wed Sep 29, 2021 7:57 am

OP @GotBugged.... Where you at?

Was hoping to see more resolution to this, OP started bunch of threads then no more activity/replies...bummer!

Hope all the talk of it being a mistake switching from FI to Carb hasn't scared you off...
Not the first (nor last) person to ditch FI... just gotta get it all sorted now and lots of folks here to help with that!

Ben

Wed Sep 29, 2021 8:53 am

Well, maybe he only gets around to checking the forum on weekends. Hopefully he'll check some of the suggestions and post back with results.

There was definitely a lot wrong there, but nothing that can't be fixed with help from everyone here. Or maybe he took the car to whoever did the changeover and said WTH???

Wed Sep 29, 2021 6:46 pm

GotBugged, the vacuum hose connections between the distributor and carburetor can be confusing. Many wrong connections are possible if you don't check repair manuals for the parts that you have on your engine. 2 years ago I replaced my dual carburetors in my '77 Beetle with a single carburetor, intake manifold, and different distributor. This was for a temporary setup; I want to go back to dual carbs very soon. All 3 components were good used German parts, and the engine has the earlier heater boxes (thru '74) so that the manifold utilizes the preheat pipes. I had cleared the preheat pipes out prior to the install and also repainted the manifold.

The distributor is a used German one which appears to be the very same one as on your engine. There is an unused hose nipple on the front-facing side of the big vacuum "biscuit" on yours. On my distrib. I put a plug over it. The only vacuum line on mine goes from the downward-facing nipple of the vac biscuit, up to the left vacuum port on the carb. That curved line is from an unused piece of brake system pipe which I polished with chrome polish. It is formed just like a factory pipe. You need that upward bend outboard of the carb because during vacuum conditions, fuel vapor can be pulled out of the carb. The upward bend prevents any fuel vapors or drops from going down the pipe into the vac biscuit and disintegrating the diaphragm inside it. But for now, you just need to reposition your hose.

What you can do is pull the long hose off the carb. Remove the distrib. cap and pull the rotor off (goes straight up). Suck on the end of the long hose and watch that "something" moves inside the distrib. What you should see moving is a flat metal arm that goes into that vac can. Might only move about 3/8" total, but that's OK. It is the ignition advance. Take the plug that's now on your carb's left nipple and cover the nipple where the long hose was.

Put the rotor and cap back on, secure the throttle guide tube in the fan shroud as already explained, and take it for a highway drive... It "should" now easily hit 70 mph and more.

Wed Sep 29, 2021 11:29 pm

Cusser wrote: GotBugged wrote: The Beetle came with a Fuel Injected engine, but we decided to have it changed out to a 34 PICT 3 carb and the engine is a 1600cc 50hp (48hp).

Any thoughts, comments, and help would be greatly appreciated.
My thought are that this was a good idea, and especially if there were any issues at all with the fuel injection system.

GotBugged wrote: When we do City driving it drives the Beetle drives okay, but when we hit the Highway it only tops out to maybe 52 to 54mph and bogs down on hills. We were thinking that we should be able to see somewhere between 65-80mph??

Is that realistic?

Absolutely realistic to get 75 mph on relatively level highway.

GotBugged wrote: when we hit the Highway it only tops out to maybe 52 to 54mph and bogs down on hills.

Any ideas on why we might not being getting full engine power? What should we look at or tweak on trying to improve the engine performance?

I see in your photo an issue with the steel accelerator cable tube that goes through the fan shroud. This might be preventing full opening of the carb on acceleration/full mashing down on pedal.

On my VWs, I add a hose clamp to the forward (hidden) side of the fan shroud to keep that in place, and so the cable can be adjusted correctly.
Your photo

Here's mine, with clamp

And if the timing was set when you still had the hoses connected incorrectly as in your photo, that should also be checked.

That's a great post.
I noticed the Distributor is set like a type 3, #1 should still be at the scribed line on the distributor. and I agree the vacuum line is at the wrong port.
Also you can't time this engine @ 5 ATDC because you are not using the retard side of the Vacuum can.
The stock exhaust on these 75-79 type 1 are not good for performance, but make good heat.
I'd loose the heater boxes, and get J tubes and 1-3/8 system, but it needs to be set up so the heat raiser system actually works.
I think AirCooed.net can get you that set up on a 1-3/8 system.
I'd go back to a Oil Bath air cleaner with the preheat tube hooked up.
The Oil Bath Air Filter has a lot of thermal mass that will be heated by the preheat system, further preventing drivability issues due to a cold carb.
I'd get a degree pully, so I could time the engine at 27-29 degrees BTDC (vacuum hoses connected) at 3000 RPM.
So you engine will look just like the one posted with the green body.
My '78 Super Convertible still has F.I. because I live in Ca. and cruises @ 65-70 no problem.