All Small Six Vacuum Leak Woes

[StarDiero75]

Howdy Guys,

In the past couple of months I have only one time had it where the car ran just like it was supposed to. It was a magical moment. It idles perfectly, it did everything it was supposedto. Then magically the leak came back. I'm running out of ideas here. It seems to me, it's leaking on the idle mixture screw side but yet, the gaskets aren't wet, i determined this from spraying starter fluid. I have replaced the power valve cover gasket and nothing changes (the cover was sanded flat by the way) Any ideas?

This is an Autolite 2100 1.08. The throttle shaft is a little on the loose side.

The exact situation is, I'm running very large jets for my 200 (dual 56s) and it still runs lean. At idle its fine but anything above that and it slowly starts to run worse. The wideband starts showing me 15.5-16.5, sometimes more and erratic, when in neutral, revving it and holding steady. When I rev it up to about 3500 it comes down a bit, to about 13.5. When cruising around town it surges then on the highway she runs a little richer than it should (probably from the larger jets). Obviously this is a leak of some sort but what?? Or is the carb just trashed?

Thanks guys,
Ryan

 

[bubba22349]

Hi Ryan, Yes it's for sure the throttle shaft that's causing your vacuum leak (and it's a very common problem on well used carb's) usally it's only the one on the linkage side that wears very much! This is caused over time by the linkage pushing against the throldle arm and the throttle return spring pulling it back. There was an excellent post that was written by FTF (French Town Flier) awhile back (in the big Ford Six forum with a link over to the Hamb were he posted the directions showing his method on how to fix these worn out throttle shaft bushings. He uses these Autolite 2100 or Motocraft 2150 carb's on about all of his race cars. A bushing kit is available on evilbay and comes with a reamer and some bushings. Good luck

 

[StarDiero75]

Hi Ryan, Yes it's for sure the throttle shaft that's causing your vacuum leak (and it's a very common problem on well used carb's) usally it's only the one on the linkage side that wears very much! This is caused over time by the linkage pushing against the throldle arm and the throttle return spring pulling it back. There was an excellent post that was written by FTF (French Town Flier) awhile back (in the big Ford Six forum with a link over to the Hamb were he posted the directions showing his method on how to fix these worn out throttle shaft bushings. He uses these Autolite 2100 or Motocraft 2150 carb's on about all of his race cars. A bushing kit is available on evilbay and comes with a reamer and some bushings. Good luck

I have seen that post by the FTF. I enjoy his posts about the Ford 300 racer. I just did my taxes and I think I'm gonna get the Sniper 2300. I've messed with with this carb enough. I'll replace them later, but I think the Sniper is the way to go. Ive messed with this carb for almost a year straight. Its about time I stop. Y'know?

 

[frozenrabbit]

Hey Ryan, have always appreciated your enthusiasm. I think you are over complicating your ride. While you should definitely get it running and idling smoothly, you've been all about tuning to the O2 sensor. Carbs are not going to be perfect on the AF ratio at all rpm and driving conditions. With the time and money you've thrown at it by now, you could have just thrown a 302 at it, and had WAY more power than you are ever going to squeeze out of a 6.

 

[StarDiero75]

Hey Ryan, have always appreciated your enthusiasm. I think you are over complicating your ride. While you should definitely get it running and idling smoothly, you've been all about tuning to the O2 sensor. Carbs are not going to be perfect on the AF ratio at all rpm and driving conditions. With the time and money you've thrown at it by now, you could have just thrown a 302 at it, and had WAY more power than you are ever going to squeeze out of a 6.

I agree with all of that. I know for a fact, this carb has some weird ass vacuum leaks. I know that for fact. I don't necessarily look at the wideband all the time. I only do when it acts up. She stumbles and surges when held at a constant rpm, until you get to 3500. When sprayed, it smooths out like butter and revs up, then goes back to surging and stumbling. I've dealt with this now for a year and I'm finally gonna throw a sniper at it. I thought about the street avenger and came close to getting it, but you're right, its a carb and won't always run right. I'll have to rejet the holley probably, replace the power valve orfices with smaller restrictors and go through that whole thing again for something that still won't run perfectly. To me at this point, i see the sniper as the better way to go. Do you see what I'm getting at? I totally want this thing to be simple, I'm not crazy about computers. But after messing with this for a year, I'm tired of it. So many weekends, trips, and money wasted.

 

[65coupei6]

You probably just need a better core to rebuild. Or get a professionally rebuilt one.

Efi is great. I love mine compared to the Holley. But, you have to remember you have the added expense of a fuel pump or tank.

 

[frozenrabbit]

Ran an Autolite 1100 for 8 years with zero issues. Load-O-Matic dizzy, with points, not even running a Pertronix.

 

[drag-200stang]

Ran an Autolite 1100 for 8 years with zero issues. Load-O-Matic dizzy, with points, not even running a Pertronix.

Yes, but he is thinking about running boost in the future...I will not run boost on a carb with no timing control ever again.

 

[frozenrabbit]

302 is cheaper, quicker, and WAY more horses. Can most definitely be done for LESS that the cost of adding EFI conversion alone.

Mid 80's H.O. 5.0 Mustang WITH factory EFI even, or from a Lincoln LSC, which is a little more likely to be less thrashed than a Mustang 5.0. A Mustang 5.0 is also going to come with that t-5 conversion, factory.

EFI, boost, NOS, and ethanol ain't gonna get a 6 there. And then, you couldn't even actually daily drive it.

 

[StarDiero75]

You probably just need a better core to rebuild. Or get a professionally rebuilt one.

Efi is great. I love mine compared to the Holley. But, you have to remember you have the added expense of a fuel pump or tank.

I have had "professionally rebuilt" carbs before and they've been just as crappy. And you may be 100% right, i am known to be an unlucky person with car parts and I probably just have bad cores.

The kit I'm getting has the fuel pump included. I already have a prefect place to mount it.

 

[StarDiero75]

Ran an Autolite 1100 for 8 years with zero issues. Load-O-Matic dizzy, with points, not even running a Pertronix.

That was one of the worst carbs I ran. I had that same setup and it ran great for 1 month. Then out of nowhere it trashed itself. Looking back, the canister on the vacuum advance probably ruptured. But I went to a Holley 1904 off a 215 and that was the best carb I've ever had. Just put that same carb on my 63 and it still runs like a dream.

 

[StarDiero75]

302 is cheaper, quicker, and WAY more horses. Can most definitely be done for LESS that the cost of adding EFI conversion alone.

Mid 80's H.O. 5.0 Mustang WITH factory EFI even, or from a Lincoln LSC, which is a little more likely to be less thrashed than a Mustang 5.0. A Mustang 5.0 is also going to come with that t-5 conversion, factory.

EFI, boost, NOS, and ethanol ain't gonna get a 6 there. And then, you couldn't even actually daily drive it.

I have been well aware of thag from the start as every inline 6 guy knows. I have a 289 in the garage that needs rebuilt and I've really thought about it from time to time. My car is essentially built for it already, i got the 8inch, 68 disk spindles and v8 steering/suspension, sub frames. She's ready for a V8, but I'm not at that point yet. I like rooting for the underdog and seeing what I can do with it. I have a 250 that I plan to boost and see where that takes me. And one day I'll finally build a V8 Falcon/Maverick with that 289 and its gonna be one badass car, but the Ranchero won't be a V8 car. Its meant to be something different and special. I'm not after balls to the wall power. just something that catches eyes at shows, stands out, is different, and still peels the tires while getting me 20+ miles a gallon.

 

[frozenrabbit]

In no way am I looking to discourge you, just seems like you are going thru A LOT of configurations, various mods, upgrades, extra steps, time, and money to get it to what ever you are wanting it to be.

 

[StarDiero75]

In no way am I looking to discourge you, just seems like you are going thru A LOT of configurations, various mods, upgrades, extra steps, time, and money to get it to what ever you are wanting it to be.

Yes you are right, but really the only thing I've been fighting this whole time is the carb. Worst case scenario too with the motor, I get rid of it and put the 289 in. That 2300 EFI will go right onto that no problem so its not a waste as I see it. Its just been a pain in the ass messing with broken 50 year old parts.

 

[Econoline]

That's the way I see it. If you've got the funds and the desire, you're not going to regret going with the 2300 tbi, it could always be swapped into another engine or car.

 

[bubba22349]

Yes you are right, but really the only thing I've been fighting this whole time is the carb. Worst case scenario too with the motor, I get rid of it and put the 289 in. That 2300 EFI will go right onto that no problem so its not a waste as I see it. Its just been a pain in the ass messing with broken 50 year old parts.

People come to this site all time with carb issues or vacuum leaks yet the Ford small six log head has only a few places that you can have a vacuum leak far fewer than most any other engine. Yet when you ask them to check the carbs throttle shaft for leaks it’s like pulling teeth to get them to look there. Chance are far more than 50 / 50 that any carb that is this old will be the likely source of the vacuum leak and with a loose throttle shaft as the cause. I have even installed many brand new Weber carbs were the throttle shafts were then worn out in only a year or two, check to country of origin some are of very poor quality. So for others site members that might see this post and having vacuum leaks please check out those throttle shafts it doesn’t matter which carb it is for a possible source of your vacuum leaks the tolerance isn’t supposed to be very much clearance.

Ryan I know that you are plenty capable of being able to make this simple shaft repair since you machined your own head to do the 2V swap. but it looks like you have made your choice now. Best of luck I am sure the EFI will be a nice very nice upgrade.

 

[StarDiero75]

People come to this site all time with carb issues or vacuum leaks yet the Ford small six log head has only a few places that you can have a vacuum leak far fewer than most any other engine. Yet when you ask them to check the carbs throttle shaft for leaks it’s like pulling teeth to get them to look there. Chance are far more than 50 / 50 that any carb that is this old will be the likely source of the vacuum leak and with a loose throttle shaft as the cause. I have even installed many brand new Weber carbs were the throttle shafts were then worn out in only a year or two, check to country of origin some are of very poor quality. So for others site members that might see this post and having vacuum leaks please check out those throttle shafts it doesn’t matter which carb it is for a possible source of your vacuum leaks the tolerance isn’t supposed to be very much clearance. Ryan I know that you are plenty capable of being able to make this simple shaft repair since you machined your own head to do the 2V swap. but it looks like you have made your choice now. Best of luck I am sure the EFI will be a nice very nice upgrade.

Very well put Bubba. Its not normally a place you'd think to look. Typically vacuum leaks aren't on the carb, they're around. ALWAYS CHECK THEM. I never did before this. I wish i did sooner.

Thank you. I know i am capable of doing this but even when I'm done, i still have a carb that leans out nasty when i take left turns, i still have a carb that richens up hard when i take right turns, i still get vapor lock, I still get all the fun of a carb. On a car I don't plan to ever sell, and to complete my vision for building one of the best 200s around, i think this is the right track.

 

[StarDiero75]

I'll post when I get the EFI on. Just got the taxes!

 

[bubba22349]

Ryan yes I think EFI is going to be a good investment on your Ranchero since you plan to keep it. I sure regret selling my last one years ago they just aren’t as easy to find now especially for a cheap price.

 

[mustang6]

Ryan I’ve also been thinking of getting one of those for a long time. I’ll follow your build, and you might motivate me to do it!