Weird problem with 1300 engine

bandi · Posted: Sun Jun 17, 2012 6:56 pm Post subject: Weird problem with 1300 engine

So I've been going through this issue with my '66 1300 for... 8 years now I guess. Bought a correct 1300 back in the day, stuck it in the car, car has no power at all under load.

Ripped apart carb, found RTV gasket maker holding accelerator pump diaphragm in, thus clogging all the ports. Rebuilt carb. Still runs the same.

Found distributor advance sticking- freed up, replaced points and condenser.

Still no power under load.

Timing is set to spec (and I've tried playing with the timing- doesn't seem to have any drastic effect on performance since). Have tried 2 other carbs, 2 other distributors, a different fuel pump. Valve adjustment has been done. Compression is great. Cam timing is correct. Engine idles beautifully and starts well. Intake isn't leaking. It just... doesn't want to move when you hit the gas and you're in gear. It's not misfiring or anything, just feels like it has about 5 horsepower. Once while driving around the block, it starting running like it should for about a minute, then went back to 5 hp mode. I even slapped some Weber carb I had in the garage on the thing... and although it now sounds incredible when you rev it up, still doesn't have enough power to get out of its own way.

Any thoughts would be greatly appreciated- this thing has driven me nuts in the past and now that I've taken it out of the barn again, I want to drive it!

Hope everyone had a good weekend.
Aaron
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OLD VW NUT · Posted: Sun Jun 17, 2012 9:01 pm Post subject:

This sounds like it might be an ignition timing issue. What are you timing the distributor at? Have you verified that the distributor advance works by observing it with a timing light as you increase the RPMs?

Worse case scenario is the cam timing was set up wrong.
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drscope · Posted: Mon Jun 18, 2012 1:35 am Post subject:

Start with the simple stuff! Check point gap and make sure you have decent plug wires.

If your wires are shot and leaking to ground, it ain't gonna get out of it's own way when you call on it to do so.
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bandi · Posted: Mon Jun 18, 2012 4:55 am Post subject:

Timing is at 7.5 degrees BTDC, point gap is set to .016".

Vac advance is indeed working, and cam timing is correct (finally broke down and checked that after the third distributor I tried Smile

)

Plug wires are new (Bosch), and plugs are new NGKs.
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veedubbud · Posted: Mon Jun 18, 2012 5:30 am Post subject:

Just a dumb question but is the firing order right? Cross one wire and you may not feel it as a misfire just a power loss happened to me on a 70 beetle
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Joey · Posted: Mon Jun 18, 2012 6:12 am Post subject:

Clogged manifold or heat risers?

Try setting the points with a dwell mater.
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Flavio · Posted: Mon Jun 18, 2012 6:31 am Post subject:

Could it be an exhaust problem....rust/clogged ?

bandi · Posted: Mon Jun 18, 2012 7:26 am Post subject:

drscope · Posted: Mon Jun 18, 2012 8:13 am Post subject:

If you are running a stock muffler, you will almost always get the same pulse out of each pipe. They just sort of go into the same can, so what ever is in there comes out pretty evenly.

Will it rev up fine when it's not under load?

And this may sound silly, but have you checked to make sure you don;t have a dragging brake or low tire pressures?

On my 55 I can tell when tire pressures are just a little off - it feels like I lost half of those 36 horses!
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ejonn · Posted: Mon Jun 18, 2012 9:48 am Post subject:

.016 is probably not enough gap. In my travels it takes closer to .020 to get a 48ish dwell.
have you verified full throttle in relation to pedal travel?
ie...full pedal =full throttle

bandi · Posted: Mon Jun 18, 2012 9:56 am Post subject:

61SNRF · Posted: Mon Jun 18, 2012 10:41 am Post subject:

I think at this point I would first try a substitute coil. I have had one break down internally and cause symptoms similar to what you descibe.

I don't suspect a Beetle exhaust would clog that easily, but you can diagnose a clogged exhaust with a vacuum gauge if you have access to one.
With it's hose connected to an intake manifold vacuum source (probably your biggest challenge with stock carb/manifold), you should have a steady 16-20 inches at idle. Rev the engine sharply and hold it at ~2000 rpm, the needle should drop to zero then quickly return to the same figure as idle.
If when you rev it and the needle stays down near zero or slowly returns to vacuum that is an indication of a clogged or restricted exhaust.
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usrname · Posted: Mon Jun 18, 2012 11:47 am Post subject:

I'm going with a fuel delivery problem. Please tell me your fuel filter isn't clogged. Could it be a problem with the filter sock inside the tank? Is the fuel line clear? Pull it off the fuel pump and blow into it then try driving.

bandi · Posted: Mon Jun 18, 2012 9:06 pm Post subject:

bandi · Posted: Mon Jun 18, 2012 9:08 pm Post subject:

drscope · Posted: Tue Jun 19, 2012 8:02 am Post subject:

Usually with a fuel delivery problem it just stops running when you call for fuel. Power remains the same until it runs out of gas in the fuel bowl and stops.
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aquavw · Posted: Thu Jun 28, 2012 7:46 am Post subject:

bandi · Posted: Thu Jun 28, 2012 8:51 pm Post subject:

Haven't had a chance to look at it yet, hopefully this weekend I'll give her some attention!

I'll post my findings here if I ever do figure this thing out.

Just out of curiosity, since I had it sitting on my workbench, I bolted the carb from my '66 onto another car at work and it ran beautifully.
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'52 Zwitter deluxe,'66 Bug, '68 Bug, '69 Sunroof Bug, '69 Westy, '71 Super, '72 Baja Champion SE, '73 Super, '73 Standard, '73 Cabrio, '74 Love Bug, '74 Super, '74 Sun Bug, '75 La Grande Bug, '99 New Beetle, '99 Jetta, etc, etc, etc.

manxcraig · Posted: Thu Jun 28, 2012 8:59 pm Post subject:

Have you checked the compression? Maybe it's worn out or stuck rings.
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Dougy Dee · Posted: Fri Jun 29, 2012 5:18 am Post subject:

What procedure did you use to check for correct cam timing?

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