RXBeetle

I just got my 12A powered Super Beetle back on the road thanks to a great deal on a motor out of a '79 FB. I cooked my last one sorting out cooling issues. I finaly got the carb to stop flooding (stupid floats), converted to mechanical secondaries, and rats nest removal of course. Timing set spot on @750 rpm
Here's the problem:

- Dizzy vac advance connected to the 2nd nipple on the carb plate (seems to be the suggested vac souce for the dizzy)
- Vac gauge shows no vac on this port at any time when revving or at idle in neutral
- Nice smooth idle when warm
- Dies not want to idle at all when cold
- Very poor drivability off idle
- High load/high rpm shifts result in 4' fire ball out the exhaust looks awesome but can't be the correct.
- Pretty sure this is NOT the right nipple, why does it seem to work for otheres but not me? *shrug*

- Dizzy vac advance on 1st nipple on carb plate 15in. vac @ 750rpm
- Vac gauge drops to 0 when engine is revved in neutral
- Much better drivablity down low
- Better idle when cold
- Idle never smooth, lots of popping
- Feels like less in the top end

Both ways result in a big backfire when I shut the car down. I am basicaly running the thermal reactor --> ~1 foot of 2.5" in pipe --> magnaflow muffler --> turndown. Not much room for exhaust with a Beetle so the backfire is comparable to a 12 gauge.

So the first nipple seems to be much better for drivablility but my idle is crap (I did properly adjust my idle mixture screw, turn in till it surges, half turn out) and it seems that the additional advance from the vacuum is what kills my idle but helps when it's cold and low end drivability.

I am running an 81 carb and manifold (metal idle mix cap Cali?) and 2GCDFIS if it makes a difference.

Any ideas as to what nipple or what vac the dizzy should be getting under what conditions?

Thanks in advance.

trochoid

iTrader: (6)

1. Get rid of the idle cap.
2. Are you running an aftermarket fuel pump, if so, what is the fuel pressure set at?
3. Check the fuel level in the sight windows on both fuel bowls, are they in the middle of both windows?
4. Has the carb been rebuilt recently, if so, were the gaskets included in the kit placed between the carb and thermo spacer and the thermo spacer and the intake?
5. How is the timing?
6. Have you done a compression test, don't worry, just curious?

RXBeetle

1. Get rid of the idle cap.
- did that,

2. Are you running an aftermarket fuel pump, if so, what is the fuel pressure set at?
-Yes, crappy puralator universal with a crappy regulator and one of those carb fuel pressure gauges that goes on the carb 0-15psi not the best setup, for what it's worth I have the regulator set at 2.5 and the gauge reads 3psi. You've got me thinkin...

3. Check the fuel level in the sight windows on both fuel bowls, are they in the middle of both windows?
-Smack dab in the middle, it took me forever to get that mess worked out.

4. Has the carb been rebuilt recently, if so, were the gaskets included in the kit placed between the carb and thermo spacer and the thermo spacer and the intake?
-I rebuilt the carb, I think I've read just about every carb rebuild post on this forum. All gaskets replaced including the two carb spacer gaskets.

5. How is the timing?
-Leading and trailing are right on thier mark @ 750rpm with the vac advance hose removed and the nipple capped. Double checked this morning.

6. Have you done a compression test, don't worry, just curious?
-Hmm, no I haven't I'll have to do that just for reassurance. I did the plugs out/ listen for consistant wooshes. I need to pull the check valve out of my gauge.

81gsl12a

iTrader: (1)

are you using the 79 dizzy? what yr was the other motor?

trochoid

iTrader: (6)

4. Most of the gasket kits I have seen do not have the proper holes for the air passages between the phenolic spacer , carb and intake. When using the spacer, gaskets are not needed and can cause problems with the blocked ports, remove the gaskets. I'm not sure what each port does, or where they go, but the gaskets may account for your not having any vacuun in the second nipple.

7. Get rid of the thermal reactor. On the 79-80's they can break down internally and plug. I don't think your's is there yet, but it might be on it's way. If nothing else, find an 81-85 exhaust manifold. Headers would be your best option, but it is going to get very loud. Saltyslug built his own, you might PM him about that. If you go the header route, you might want to concider seperate pipes and a Magnaflow on each one.

Vacuum advance works at low rpms and initial thottle input, after that the mechanical advance takes over. You might want to check the weights and springs inside the dizzy to see if they are fully functional and not binding or sticking.

Flamage is normal when the cats and air pump are removed, your's sounds a bit much. Some of that is due to the short exhaust. Make sure your trailing plugs are working and are you using 2nd gen plugs for the leading?

darkfrost

iTrader: (1)

And your fuel pressure regulator, if its a dial-style - it will NOT supply enough fuel at high rpm that the rotary needs.

RXBeetle

The dizzy is a later one (hall effect with ignitors on the body of the distributor)
The motor itself is a '79 the intake and carb are off my apex seal-less '81 12A

I did that:


but I sold it when I blew the first 12A. I am building a streetported megasquirted 13B which will I will be welding a nice stainless header for, this 12A motor was cheap and I just wanted to get it runnin with the least amount of extra work and $$. The thermal reactor is in pretty good shape, I'm running it backwards to get the exhuast to exit toward the front of the engine (back of my car). I am using a gigantic magnaflow that scrapes the ground often. I have no sound deadening material and solid engine mounts. Loud? I can't hear anything...
Yes, 2G coil is on leading plugs.

I installed it without gaskets my mistake first and got a lot of vacuum leaks, I might have to just go through and make sure all the passages have a corresponding hole in the gasket/punch new ones as needed.

Damnit I have one of those on there. Time to hook up my LC1 and get a new fuel pressure regulator. I don't have a return line. Is there a good low pressure regulator that doesn't require a return line? Maybe run 2 in paralell for more flow? a little hack, I'll need a return line for the megasquirt anyway, I might have to just route one with an appropriate regulator.

Thanks for the help.
Shopping list:
Fuel pressure regulator
Fuel pressure gauge

RXBeetle

Got the holly low pressure regulator and an autometer gauge. I also found a little vacuum leak, problems solved. The old regulator was not keeping up with flow on hard acceleration. I was doing a little testing on an empty back road and while burried in third gear I see a vehicle on the horizon so I back off and slow down, too late, it was a cop. I busted doing 25 over. doh! the officer was really nice though and was impressed with my work. The decklid was off so the whole engine was hard to miss. We talked cars for a minute and he asked about my setup. He even had me start the car up and rev it for him, and noticed the 2nd gen dirrect fire coils! He ended up only writing me for 5 over (thank you thank you thank you...) honestly There's no bitching from my end I was in the wrong and he cut me slack. He did however tell me about two nasty head on accidents on that road that he got called too. I got the message loud and clear. Just goes to show you there are some car guy friendly cops out there. Thanks for the help guys and keep it safe.