So I'm driving my 914 home in Charlotte 5:00pm rush hour traffic (down Independence Blvd for you locals) and my rpms go up to 3000. I have had this happen before but was able to lift the accelerator pedal to unstick a cable to return to normal...not so this time. I stop in a parking lot because I'm convinced the cable is stuck and holding the carb open..... not so, the cable is fully retracted. Get back in the car, then the rpms go up to 4000, then 4500 and I'm having to drive the car by braking and feathering the clutch all the way home, about 15 miles. By the time I got home, a little smoke and I could smell the clutch. I have not started it since. FYI- I have a 1.7 L with a single carb (been told its a Weber) that I have had for about a year and I have no history on the car or carb.

Two questions:
1. Is it time for a carb. rebuild? How much does a kit run? Or time for a new carb.... or switch to new carb(s).?

2. Does this mean my clutch is spent?

Photo of carb.
Click to view attachment

The very first thing you should do is determine the ststus of the throttle plate. If it's not closing all the way, there's the fundamental issue. Disconnect the throttle cable at the throttle arm of the carburetor and see if that fixes it. If not, remove the air cleaner and take a look down the throttle bore. Something stuck in there? Choke stuck on? If removing the cable solves the problem, look at the pedal, the rod, the bell crank in the pedal cluster, and the front end of the cable. Disconnect it there and see if it moves freely. Report back.

The Cap'n

Are you not missing a hose from the oil fill/PVC valve? Chech for vacuum leaks all around.

Clutches can take a good deal of abuse so unless you were extreme in riding the clutch it may be ok.

But overall if it is the carb, don't go back single.

Make sure your cable is not wrapped around any other cables in the tunnel.

double check the bell crank like Cappy said. A weak weld joint that can allow the cable to lodge against the tunnel wall. is your pedal stop adjusted properly? if not you may have bent it already!

High RPM is more air into the throttle assembly, either by wire, throttle open, plenum allowing air in, or a combination platter.

I had this happen to me with a type 1 1776 with dual Webers . Coming into LA on I5 during rush hour, the RPMs shot up to around 3500. I too thought the throttle cable was sticking as it was intermittent. I made it all the way back to Texas before realizing the right side intake runner nuts were about to fall off Check those runner boots for holes, and see if the runners loosened up at the heads.

Your car didn't try to kill you. What it did was remind you that it is very old and needs constant care. Kinda like Capn' Krusty.

Guys, thanks for all your posts... a wealth of wisdom. So I had some time this weekend and disconnected the cable from the carb via the bell housing and discovered the problem (see the photo below). The cable was "too short" to allow the throttle plate to close, thus the 4000 rpm. So I think maybe the recent cold weather shrunk the cable (so I thought). I adjusted threaded bell housing to extend the reach, reconnected it and viola, the throttle plate closed. Took it out for a test drive, within a few miles....4000 rpm again. Back to the garage, pull off the cable, same thing again too short...Hmmm am I in the Twilight zone, maybe I didn't extend it enough? No more threads left on the bell housing, so I fed some of the cable of the out bell housing so there was even a little slack, then re-attached. Drive to work this AM...... 4000 rpm again!

Oh yeah... I realized I don't even have pedal stop !

So, using the collective wisdom of the previous posts, this is probably not a carb issue, but a bent bell housing at the pedal end. Do I inspect this area by taking off the pedal board and is the bell housing at the pedal end the same as the one at the carb?

Can this be re-straightened or do I need to buy a new cable (PS - I know that my cable is frayed at the carb end).

Thanks in advance for your help.
-Don

Click to view attachment

Is it sliding in and out of the sheath easily? Likely binding up/splitting. That fray is a problem, too. It can catch on stuff and keep it from letting the cable release.

Click to view attachment
[/quote]

at some point soon you should consider replacing those boots that connect your plenum to the runners. They all looked pretty cracked. That will make a big vacuum leak and certainly not help the situation. Naturally this is after you fix your frayed throttle cable.

Kelly

with dr.evil.

Yes, the cable pulls freely in the sheath, when I disconnected it from the carb, I had my son press the accelerator and I was able to gently pull it back at the carb end.

What has me baffled is the "return point" of the cable seems to be changing. Everytime I adjust the cable so the throttle plate is closed, then drive it, the darn throttle plate end up "open" again to the same point that causes the 4000 rpm. That is why I wondered if I bent something each time I depressed the accelerator pedal (since I don't have a pedal stop).

There is a piece of spring steel on the bottom of the gas pedal and is a big part of helping you have a cable return.
Pull the rod off the back of the gas pedal so it stands free of anything and see if when you push it down, it comes back up again on its own.
If not, you need a new one.

The piece of steel is molded into the pedal.
Yes, there are lots of wrong ways to do it, or you can buy a new pedal.

If your ground strap on your transmission is worn out or dirty then your accelerator or clutch cables can be acting as your ground. Apparently, this makes them act funny.

Or at least I have heard the grey beards on here muttering about that...

John

That cable is trash. I'm almost certain that the fraying is what is causing your problem. Do not cheap out on this one - it's your life and that of your passengers. Order a new $20.00 throttle cable from Pelican Parts. At least you can start there and we can check that one off the list of variables.

Thanks guys. I do need to go ahead and check the ground strap and order a throttle cable. I'm thinking of possibly going dual carbs, so would I need a different cable set-up? Seems the same cable should work, but I wanted to check.

Does the throttle plate return smoothly without the cable attached? You could have some carbon buildup around the shaft that needs to be worked out with some carb cleaner and elbow grease. Make sure there's no stiction at all in that assembly.

Yes, I used carb cleaner and sprayed the carb while running. As soon as I disconnect the cable from the carb, it returns to normal idle.

Now when the engine is off and I push down on the throttle plates manually, they do not return fully to closed position (see photo below), but as soon as I turn the throttle on the carb, the return to fully closed position. I just assumed I created a "choked" position with the carb when I manually pushed them down, but maybe this is a problem too?
Click to view attachment

I'm no expert on the Pinto carb but I'm pretty sure that's the choke not the throttle plates you pushed open and it's not relevant to your issue.

Sorry if this has already been answered but when it is doing the high idle, can you bring it down by pulling up on the pedal?

And, please get a new cable. The stock cable works fine with most carb linkages for duals.

That's the choke plate. You need that wide open to see down into the carb and the throttle plates. Disconnect the little ball attachment on the linkage of the carb and see what happens, again with the engine off. Does the throttle fully return to stop smoothly?

That being said, if you go to dual carbs, most setups can utilize the stock 914 accelerator cable, complete with the *correct* crimped ferrule end. On the single carb setups like yours, that ferrule/end of the cable must cut off so you can feed it into the pivot ball attachment, which eventually causes the cable to fray. If you buy a new cable and use it on that carb, you'll have to buy another one if/when you go the dual carb route.

Might I suggest if you indeed go the dual carb route that you look at SteveGM's carb setup in the classifieds? That is a complete setup, ready to go - all you need is a new throttle cable. This is a beautiful setup and looks plug-and-play. Only needs new intake gaskets and the throttle cable.

If you want an even better solution, easy to synch and with great throttle response, look at Tangerine Racing's cable throttle linkage setup. Chris makes a phenomenal product and his setup uses the stock cable with no modifications as well.
www.tangerineracing.com

My carbs (http://www.914world.com/bbs2/index.php?showtopic=245178) came off of an engine that I drove in the car last week. They are complete. I bought the car which had a new engine and had been run only an hour. I drove the car around the block last week, pulled the motor, and pulled the carbs. I believe your accelerator cable will work fine with them. But, you really need a new cable. That one is frayed pretty bad.

George,
Thanks for the suggestion. As you can tell, my carb knowledge (and terminology) is limited at best. Not knowing what they were called, I did already ensure the true throttle plates returned to normal position... and initially only one opens up then as the throttle increases the other opens up... I'm guessing I observe the definition of "progressive" carbs, correct?

Funny thing is I already spoke to Steve about his carb set up, but he was not sure if it was appropriate for a 1.7L engine. I've seen some threads that certain sizes (40, 36, etc.) were only appropriate for certain engines. I know you have rebuilt carbs before, what are your thoughts? Also, I noticed that Redline sells dual carb set-ups for @ $400 without the linkage bar (http://www.webercarbsdirect.com/product_p/wk412.htm) I'm assuming these are not "real" weber carbs or a modern knock-off. What do you know about them?

Yep, that's why it's considered progressive. See, you know more than you think. The secondary comes in mechanically on the Weber 32/36 (what you have on your car). On old American carburetors you might have heard the term "vacuum secondary". Same idea - the secondary throat comes in adding more fuel and air under increased engine load, but uses vacuum signal from the intake.

Find out if Steve can give you an idea of what size venturis (chokes) are on this dual carb setup. With 40 Webers and the 1.7 you have you want 28mm venturis (usually what they have stock). He can look down into the barrels and see the number stamped on the top of them.

The Redline units are EMPI carbs - search here and you'll see that they're very hit or miss. Lots of casting problems and other issues. I've never tried them but after reading what everyone else says, I wouldn't bother.

[quote name='blabla914' date='Nov 11 2014, 09:32 AM' post='2109229']
Click to view attachment
[/quote]

at some point soon you should consider replacing those boots that connect your plenum to the runners. They all looked pretty cracked. That will make a big vacuum leak and certainly not help the situation. Naturally this is after you fix your frayed throttle cable.

Kelly
[/quote]


tighten all bolts around the carb body

My carbs have 32mm venturis, based on the receipt for them. I looked down in there and didn't see the stamping. I have heard that 32s work with a 1.7, and I have also heard that 28s are better. But you can always change them out. If you want them I'll take $650 for the whole set up (carbs, manifolds, linkage, and filters) to help cover the cost of new venturis.