1978 Super Beetle: Engine Performance

[GotBugged]

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.
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1978 Super Beetle Convertible - September 2021 - Current

[Glenn]

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.
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Glenn
74 Beetle Specs | 74 Beetle Restoration | 2180cc Engine
"You may not get what you pay for, but you always pay for what you get"

Member #1009

#BlueSquare

[sjbartnik]

[busdaddy]

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.
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[Cusser]

[johnnyvw164]

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.

[MuzzcoVW]

[MuzzcoVW]

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?

[old gh bug]

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

[Q-Dog]

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.
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Brian

'69 Dune Buggy
'69 Beetle Convertible
'70 Beetle

[old gh bug]

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 .

[virusdoc]

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.
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1976 Convertible Super Beetle, "June Bug".
FI-->34PICT3 carb conversion-->now dual 40 IDFs
Self-rebuilt 1904 (after totally botching a 1641 rebuild, cussing a lot, and throwing lots of cash in the fire)

[Jimbug57]

You might consider this for winter driving -

https://www2.cip1.com/c21-2139/
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Repeat after me "I am smarter than metal!"

[vwoldbug]

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

[Max Welton]

[polypetalous]

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

[johnnyvw164]

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???

[Rome]

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.

[ach60]