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Posted by: terrymason Dec 3 2006, 11:27 AM

Could you guys take a quick look at this video of my carb:

http://drunkencrab.com/temp/carb.mpg

The barrel on the right is to the front of the car if it matters.

This is a single progressive carb (which I have no experiance with up till now). Should I be seeing fuel to both barrels, or is this working as it should? My car runs pretty poorly, and has no real power (I have to race the engine to take off).

Thanks guys!

Posted by: ejm Dec 3 2006, 11:44 AM

Looks to be working correctly, the second barrel opens mechanically around 3/4 throttle. These carbs generally have a big off-idle flat spot that's worse in cooler weather. That may be why to have to race it to take off?

Had one of these carbs on my first 914, always wanted to give it the float test.

Posted by: terrymason Dec 3 2006, 11:51 AM

OK, that makes sense. I think the air filter hasn't been cleaned in a couple of years, and it already seemed a little better when I took the old one off.

Thanks for the help.

Posted by: terrymason Dec 3 2006, 11:53 AM

well, along the same lines - the electronic choke doesn't seem to be working. Is there a simple way to test that? Should the flaps move as I turn the key off and on?

Posted by: So.Cal.914 Dec 3 2006, 11:55 AM

Back in 82 I ran one of those set ups for about two months and it never

ran right. Its like pouring raw fuel into the cylinders. You really would be better

offf running two one barrels.

Posted by: terrymason Dec 3 2006, 12:01 PM

I totally agree. I'm getting two dellorto carbs from a guy on this board, but it's going to be some time before I get them - and probably longer before I learn how to sync them.

The car idles great, and works fine under speed, but when the light turns green I really need to rev it up to 3k to gently pull out.

I think 50% of my problem may have been the air filter, and I've put about a can of carb cleaner down it - that may have helped.

I'd really like to get a good understanding of this carb, and how it works, in case I need to continue running this for a while.

Posted by: So.Cal.914 Dec 3 2006, 12:15 PM

Mine ran the best after a good tune up. What color are your plugs? Is it probably

running really fat at the low end, it's the nature of the beast from my experience.

Sorry I don't have better news for you.

Posted by: Flycut Dec 3 2006, 12:25 PM

You really need to make sure the electric choke is working properly, Make sure your positive from the coil is hooked to the male connector at the front of the carb. I would also advance timing by ear, Meaning until you have detonation at hard throttle while driving and then back off timing until detonation is not present.
Make sure all the ports your not using on the carb are plugged up. What kind of dizzy are you running?

Posted by: ejm Dec 3 2006, 12:43 PM

Good way to cook an engine..... just because you can't hear it does not mean it's good..... use a timing light

Posted by: Flycut Dec 3 2006, 01:00 PM

I agree and disagree.....I will time my engine with a timing light and then push the advance beyond.....Always get a better running engine. I've been doing this for 20 years to various aircooled rides and have never cooked an engine. The 32/36 carb will never run well unless timing is maxed out! It will be obvious timing is to advanced when car has a hard time cranking when starting, When this occurs retard timing until engine will crank normally. Advance will be beyond the 27 degrees reccomended for injection timing. Try it you might like the way your car runs under 1500 RPM. There are book facts and then real world tried and true findings. IMO

Posted by: terrymason Dec 3 2006, 01:21 PM

I have just started getting into the car, and have no idea what dizzy I have - is there an easy way to tell?

And I'm not really sure what you mean by detonation - I assume that the motor will make a different noise?

Posted by: So.Cal.914 Dec 3 2006, 02:37 PM

Detonation = pinging.

Posted by: Flycut Dec 3 2006, 05:11 PM

Post a pic, and or give us some numbers off the body of the distributor.

Posted by: SGB Dec 3 2006, 05:15 PM

Have you changed the spark plugs? That can be a big proponent for combustion.

Posted by: mikez Dec 3 2006, 05:20 PM

That carb was designed for a PINTO...remember them? Explode on impact????

Give it the float test and get some duals....

Posted by: Jake Raby Dec 3 2006, 05:34 PM

The best tool for working on these carbs is an 8 pound sledge hammer.

I take pride in crushing every one that I get the opportunity to interact with. Horrible, absolutely worthless!

Posted by: bd1308 Dec 3 2006, 05:41 PM

i thought about covering the runners with old cyrix chips, and then lighting them up with 5 volts of power to keep the runners warm.

Posted by: Flycut Dec 3 2006, 06:52 PM

Engine will be a totally different animal with duals, And a mallory.

Posted by: PORobinSCHE Dec 3 2006, 07:44 PM

FLY, appx how far are you pushing the Dist past 27 degrees? 30-32?
i would do the same on my old 74 Vette. stock time it then advance till it pinged. after that back it off appx 3 deg on the timing wheel. turned out i was at 35 degrees . ran super on bottom and mid range. i didn't race it so never worried about fall off on the top.

my 02
Robin

Posted by: bd1308 Dec 3 2006, 07:57 PM

Hmm, I'm wondering what the HEAD temps are when you do this?

I have found that advancing timing leads to higher temps....

Posted by: Al Meredith Dec 3 2006, 08:41 PM

When these carbs were shipped they included a .60 idle jet for use on bigger engines like a 914. Take out the idle jet on the primary side and drill it out or find a bigger jet. It will come off idle fine. (TWO) I always use metal gaskets at the head. This way the long runners get warm and the car will run better. Look at the number of the idle jet , bet it is too small.

Posted by: eg914 Dec 4 2006, 12:21 AM

terrymason,

It looks like our question about choke operation was only partly answered. The choke element is a bimetalic coil. As it heats up it opens the choke. It takes a few minutes to warm up, and then a while to cool down. It is not on-off with the key.

I have the same carb on my car. The discharge of the accelerator pump is deformed closed on the primary bore, and only squirts on the secondary side.

This is a terrible carb in the winter! The intake runners actually feel VERY cold when the car is running. It will run fairly well when warmed up, if the outside air temp is above 50F.

Posted by: bd1308 Dec 4 2006, 12:31 AM

i had one of these carbs, and it worked OK, but it felt like it ran lean.

I know very little about carbs, and hats off to ANYONE who can sync two carbs. I've always wanted dual progressives though.

Posted by: Flycut Dec 4 2006, 01:18 AM

I recently ran a 32/36 progressive on my 2.0, Finally got it to run properly by setting air/fuel ratio screw to 2 turns out and hooking up the electric choke.
Engine would hesitate and sputter under 1500 RPM without choke working properly. Buy a set of 40 Webers with 28 venturis, 120 main jets, 200 air correction jets, F-11 emulsion tubes and 55 idle jets. Make sure to get the Empi short manifolds not the CB Performance tall IMO I have both manifolds and the tall CB Performance manifolds create a lot of issues with clearance. Run some Dual 40's and experience all 90 HP in you 914

Posted by: dinomium Dec 4 2006, 11:57 AM

The problem is you the carb is not dead center. If it is scewed one direction or the other, the airflow is messed up. I had the same issue.
Best solution is dual carbs or FI. It is not a bad lil carb if that is all you can afford right now, just a PITA to dial in...

Posted by: maf914 Dec 4 2006, 03:16 PM

A carburator works by air velocity drawing fuel through a series of ports and jets then mixing with the airflow. The fuel then begins to vaporize, which requires heat absorbed from the airflow. The air/fuel mixture is now acting as a coolant and it has a long way to travel in the single carb configuration. This system is struggling from the start. To fight this VW added a heat riser pipe to their old single carb Type 1 engines.