225 vacuum leak and stumble

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charger426

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Just picked up a 71 swinger and I plan on putting a big block in it. However, for the time being I want to drive around with the slant 6 thats in and enjoy the car some. I have a vacuum leak and a stumble off idle (only when I mat it). I think I have found the leak by spraying carb clean at different spot on the carb/intake. The leak shuts up when I spray carb clean at the #1 cylinder (first one, closest to the grill) intake port. I turned the car off and sprayed some break free on bolt and plan on trying to tighten it some in the AM. Any other ideas on how to fix this for free-cheep?
 
So I went out and and tighten the bolts and it did change it some but not enough to really talk about. But while I was under the hood I took the the air filter off and worked the throttle from under the hood. I noticed the accelerator pump wasn't working when I gave it gas. I've read that the accelerator pump on these carbs are vacuum operated and have a tendency to go bad. Does this sound like a likely problem to anyone else?
 
The accelerator pump is not vacumn operated, it's mechanical. If it's not working well the car will stumble on takeoff. Sounds like it's time for a carb rebuild.
 
So over the weekend I took a flashlight and watched down the throat of the carb ask I worked the throttle. Everything looks fine, ie nice strong flow of fuel down the carb. I've ordered an intake/exhaust gasket and plan on changing that out next since that's where my vacuum leak is.
 
demoman3955 said:
if its a vacumm leak, spraying the leaking area will change the idle speed of the motor more then the sound.
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Yep thats how I found it. Sprayed around the carb with carb cleaner and didn't change anything. hit the #1 cylinder with carb clean and it shut up right when I hit it, also lowered the idle some (just like if you sprayed down a carb while its running).
 
So I went ahead and changed the gasket and then the car wouldn't start. I pulled a plug and checked for spark...nothing. assuming that the point/condenser took a dump and noticing that the wires were date coded 4-70 I went ahead an did a complete tune up (cap, rotor, wires, plugs, points, and condenser). After that it would start but didn't want to run. So I checked the coil by pulling the wire from the coil off the cap and check the color of the spark, came back orangeish so I replaced the coil and ballast resistor since I know they tend to just go bad. Started better and ran a little better but was missing some. I sprayed some carb clean under the carb thinking the old gasket was hard and not sealing well, sure enough it sucked in the carb clean and the RPMs picked up. Changed the gasket and it started a ran but had a bad miss and wanted to die off idle.

So I double check my point gap, plug gap and tried to get timing to as close to TDC as possible able and not its hard to start and went it does start it wants to die. I'm at a loss and super frustrated with feeling I'm throwing money at this motor that I'm just going to rip out anyway.

Do you guys have any ideas???
 
Hmmm....so it was running basically OK, and then you changed the gasket and now it does not want to stay running? Seems like the gasket change is where I would focus.....Sounds like the ignition was a bit weak but not too bad.

Did you use any gasket sealer on it? I would apply a thin skim coat of blue RTV on the intake only. And how did you torque the bolts? In what pattern? And did you replace all the trigangular washers, the acorn nuts, bevel washers, and such EXACTLY as they came off? If not, then I would remove the manifolds and put everything back in the right order; that is kinda important.

When you pulled the carb to replace the base gasket, did you turn the carb over and let the fuel run out of the vent and see if there was any rust in it? I would not hesitate to pull the bowl off ot look inside for rust.

Have you adjusted the idle mixture screw in the base, once the car is warmed up? It could have been enriched a lot in the past to compensate for the vacuum leaks.....

Is this all happening cold? If so, is the choke closing when you push the pedal to the floor and release once prior to a cold start?
 
I'll assume you've double checked that the plug wires were put back in the right order.
Must be the umpteenth time I've typed the following...
All new parts in/on a worn out distributer is a waste of time and money.
A reman'd distributer will include all those parts. In some cases the result is like dipping the engine in the fountain of youth.
Also, Spark timing printed anywhere you read it ( like 10 btdc ) was based on real gasoline. You'll need to jack the base timing up to get a good burn from todays fuel.
 
At this point it doesn't even want to start so getting it to warm is kinda imposable. Before the last plug and point gap check it was able to run just with a missing cylinder. The choke will come on (close) when I hit the gas to prime the motor at start and would open up slightly once the motor was running.

I haven’t taken carb apart at all or turned it upside down. I know it is getting fuel and dispensing fuel but how effectively I don’t know.

I put all the washers back they way they came off (laid it out on the floor) but given the grease pen markings on the intake and exhaust I don't think they used the right washers throughout. Only two of the bottom set of washers had the triangle style washers when I thought they were all suppose to be triangle style. I also have a broken bolt on the middle bolt that holds the intake and exhaust together.
 
RedFish said:
I'll assume you've double checked that the plug wires were put back in the right order.
Must be the umpteenth time I've typed the following...
All new parts in/on a worn out distributer is a waste of time and money.
A reman'd distributer will include all those parts. In some cases the result is like dipping the engine in the fountain of youth.
Also, Spark timing printed anywhere you read it ( like 10 btdc ) was based on real gasoline. You'll need to jack the base timing up to get a good burn from todays fuel.
Click to expand...

Yes triple check the wires based on the stock cap and wires I took off, and a diagram I found on the slant six forum. Car does have 66K miles on it and from what I've read/been told about the /6 the distributer shouldn't be worn yet. I know the plastic gear is a problem spot but when I the points I pulled the distributer and it looked fine.
 
charger426 said:
Yes triple check the wires based on the stock cap and wires I took off, and a diagram I found on the slant six forum. Car does have 66K miles on it and from what I've read/been told about the /6 the distributer shouldn't be worn yet. I know the plastic gear is a problem spot but when I the points I pulled the distributer and it looked fine.
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What you're looking for is variance in gap/dwell that comes from 3 places, worn lobes on the shaft that you could see, wear that allows the shaft to move varying the gap that you might see if you look for it, and that changing more as engine temp changes that you wouldn't see. Wanna look again ? LOL Good luck with it.
 
charger426 said:
I also have a broken bolt on the middle bolt that holds the intake and exhaust together.
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Hmmmm...sounds like I would focus there at least for the flat miss; kinda hard to expect the intake to seal right with a missing bolt, especially with a new gasket.

OK on all else, like the choke. Since it ran fairly decently before except for the one flat miss, I would not be focusing on the distributor yet, specially with that mileage. Could you check the timing with a light? If it is reasonably steady, then I would take that as a sing that the distribotor was in denct shape.

Has the car been run much in the last few years? I ask as it could well be there is crap in the tank that is not working its way into the fuel system.

How does the spark color look now that you replaced all those ignition parts? Just trying to rule that out before moving on. Odd that the ignition systme just crapped out with the gasket change.....did you do anything else during that process?

Have you done a compression check? Sounds like a 'bad miss' is a common theme here...
 
The bolt is one of the three that hole the intake an exhaust together not the intake and exhaust to the block. Would that bolt make a difference? I thought it bolting them together was heat exchange thing.

The car had sat in the guys garage for about 2 years and had about 1/4 when I bought it. I filled it up with some super and put a small bottle of Lucas in it. Other than the vacuum leak (which I'm assuming caused the stumble) it was running fine. The only reason I went down the road of doing a tune up was I didn't have any spark so I assumed the condenser went bad. Plus while I was on that side of the motor I noticed the wire were from 1970.

I haven’t checked the spark color since I changed the ignition parts so I couldn’t tell you the color off hand. But I agree with you that it does seem weird that the ignition system would just die and/or something else would just break/die because of a gasket change…..hence why I’m stuck.
 
OK, that bolt; I did not understand.

Well, I would check the spark color/length in open air so I could possibly eliminate that as a problem and move on to other things. With no spark, what you did was rational...I just have to wonder what happened in the gasket swap to make the spark die.....I assume that you were just working on the driver's side of the engine.

Well you do know that the BB build is going to take 2x as long as you think so this is all good!

Modern gas sitting for 2 years will be bad. It could well have been 1/2 of a tank when it was last put in the garage by the PO. Check the fuel and I bet you will detect a smell lilke some dawgs pee'd in the tank. I have damaged an engine (Jeep 151 ci) when starting and running some old gas. At least you put premium in it to dilute it some, but it can still do bad things.

How about carefully (like not inside the garage or right by the house) running the car out of a partial jug of new gas to the fuel pump and see how it does? Just an idea to confirm/eliminate the possibility of bad gas. I have only been on this forum for a handful of months but several problem cases of old gas have showed up in that time.
 
I just went back out and checked the spark from the coil and it was blue now and pulled the #2 plug and it sparked just fine. Also doubled check that I'm getting fuel by pumping the gas with my finger in the carb and it came out covered in gas. Really at a loss for why this thing isn't running.
 
Were the bolts that hold the intake and exhaust manifolds together loose when you torqued the manifolds to the cylinder head?

Did you get the gasket surfaces good and clean?
 
If I remember correctly yes they where loose but I'm not 100% sure as its been a few weeks.

Yes the mounting surface was clean.
 
charger426 said:
I just went back out and checked the spark from the coil and it was blue now and pulled the #2 plug and it sparked just fine. Also doubled check that I'm getting fuel by pumping the gas with my finger in the carb and it came out covered in gas. Really at a loss for why this thing isn't running.
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Just an FYI, having a spark jump a .035" gap in open air is meaningless since firing a compresseed fuel/air mixture is a whole different problem. But a chekc for a good spark across 1/4" or more is a good test. Sounds like the good tune up did what it should.

OK on the gas in the carb, but that is not the point. Bad, old gas mixed with good gas may or may not ingite well. That is the reason to run it out of a 1/2 jug of known good gas. The idea not to see if you are getting the stuff from the tank but if the stuff in the tank is dodgey.

I would:
- Remove and reintall the manifold with a thin coat of blue RTV on the intake; this is just beacuse the worst problems reportedly started when the change was made and maybe something is not set right. It might also not hurt to put a vaccum guage to check the manifold vacuum if it does run at all; that may to may not give meaningful info.
- I'd run a compression test in conjunction with the above; that should show any stuck valves.
- If a cylinder shows no//low compression, then pul the valve cover to see if the valves are closing and try to free them up.

Stuck valves seems to be pretty common on these when sitting for years or if gummed up with old gas.

If compression is OK, and the manifold seats good, then it is on to the carb for a rebuild.
 
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