Technical Triple Deuce Missing & Hesitating

I read your first post yet again & this really sounds like dirt in the fuel system.

Did you look inside the bowls on these carbs yet? If they sat around until gas dried up in the bowls, then little bits of dried crap are shaking loose randomly and plugging up the jets.

 

Swap out the coil.

 

Here's one of those electrical natured carburetor problems.

Missing and sputtering generally aren't caused by carbs. When a carb is involved, Missing is almost always an electrical problem. Fuel injection is a completely different matter. With a carb, a common plenum feeds all cylinders the mixture that's in the manifold. Some triple carb manifold can have irregular fuel distribution problems within the manifold.


This thread and your other one are interesting. You have a classic drivability issue and those are fun but can be challenging. Solid trouble shooting, definitive tests, and a good noggin will get you sorted out.

There's three reasons why plugs get black and sooty. Incorrect fuel fixture due to carburetor issues, not firing due to electrical issues including the wrong plugs, incomplete ignition due to compression loss.

My methods go for bottom up approach and easiest to eliminate first and that's compression. You have the plugs out any way right?

General tune up replacing all wear items and starting with a good base. Do the tuneup dance and get things where they are supposed to be. This would include knowing your distributor advance curve. Know your vacuum specs and compare those to actual part throttle engine vacuum measurements. Make sure that all matches.

At this point you will no longer be flying blind and can easily find your problems.

 

You need to get it on a dyno with both mixture and electrical diagnostic equipment
only sure way to find and fix the problem

 

My set up has no holes drilled in the center carb. I using a Comp Mutha Thumpr cam hyd. roller cam with 235/249 duration @0.050 with 1.6 rockers ( too much). I'm using a Mallory elec. dizzy set at 34 total with around 15 initial. You might need to check the float setting on all carbs. I had the outer carb bowls set too high allowing fuel to flow at idle and off idle. Sometimes the float needle valves would stick so I replaced them. I did raise the idle RPM to around 900. Try bumping the pressure to 4.0. What type of air cleaners elements are you using? I was using the cheap paper ones and they are restrictive even though they look clean. I purchased K&N ones and noticed the engine was breathing easier. Keep at it!

 

3 rochesters don't really need a regulator, they can run fine way up there, sounds like your secondary carbs are not closed enough.They have to be completely closed, no gap what so ever. Also are the secondary carbs "real" secondary carbs or converted?
JimV

 

Not using air filter. I have steel screens placed in the stacks.

 

I don't know if it is a "real"secondary carb. I didn't build the set up. How can I tell?

 

Really? The only way?

Im curious , Where does this thinking come from ? Why is taking the car someplace else and letting them figure out what's wrong the only way to get it sorted out?
It's not a mystical problem that requires a sorcerer or a medium to decipher a grey area or black arts. It's a mechanical engine with a black and white problem.

 

Choke horns or remnants of chokes on the end carbs

 

Yes.. It appears that the outside carbs were at on time primary carbs

 

You need to check the power valves in the carbs.

 

for the carb color to be at all meaningful the engine has to run at a constant load rpm for a while, shut off quick and clean. Otherwise it is an average of all running. Some tuners say the mixture ring is down inside the plug on the insulator and pretty much invisible on a used plug.The carb has several circuits to cover all operating conditions, with most overlapping with others to some extent. The idle mix screws to varying extent cover idle, transition throttle opening (but accel pump does much more) and running with throttle nearly closed. I'd start with looking at a fuel sample caught in a clean Pyrex cup taken today right from the fuel line at the carb. Any murkiness is water, and should go clear with a splash of isopropyl dry gas. Slightly crappy gas can cause some strange running, but probably not the sooty plugs you report.

 

if the shoe fits---get he center carb right it does not require a "special carb" any similar two barrel will work ---tune it as you would any car with a two barrel intake then work your way out---works every time...

 

This is what I called the "economizer". Different manufacturers call it different names, but most carbs have them.

 

Listen to Tommy here....And the guy that says some of your info is BS is also correct...Start with a "NEW" set of plugs with CORRECT gap...

 

At this stage he does not know if it is running rich or lean or both or has electrical miss fire or if the timing and advance are off
it is all just guess work it can be fixed by doing lots of test drives and adjustments yes
but on a dyno he can see what happening in 5 minutes then he can fix it himself knowing what happening

 

The secondary carbs should not have power valves just accelerator pumps. The holes above the butterflies are vapor relief holes, they won't be a vacuum leak (they are above the throttle blades) and won't change the idle.

 

I had a problem with surging with my tri-power set-up. It appeared home-made so I bought a base plate kit from hotrodcarbs.com and rebuilt my set-up. What a difference. The surging and missing stopped. My other car also had tri-power and the manifold was leaking, sucking fumes from the lifter valley.

 

you can tell by hole up near the top of the carbs were a choke butterfly might have been, Blanked out or idle screws missing or turned in tight & also the power valve inside the fuel bowl being filled.
jimv

 

The end carbs. will not have the idle mixture circuits. They will be plugged. I agree with 31Vicky with a hemi. You'll figure it out. A shop will cost you a shit load of money and you won't learn a damn thing. Once you solve this issue, you'll feel great and you'll be more confident to tackle the next issue. I rebuilt my center carb. The needle was sticking allowing the float to operate erratically. I made block off plate for both end carbs and tuned the motor on the center one first. Just like the a few of the others stated. A regulator is needed, IMO. I use a standard stock fuel pump. No fancy shit. Oh and inspect the carb. to manifiold gaskets.

 

You guys are awesome! I'm going to make block off plates for the outside carbs right now and start from there. Yesterday I changed the plugs to AC R45TS gap at .045 (from AC R44T gap .055) and runs better but not perfect. I will report my progress after I get the plates made and installed.

 

Drivability and chassis dynability (is that a word) are two very different things. No body "street drives" on dyno, its tuned for WOT with the goal of measuring or increasing peak numbers. part throttle drivability is of no concern nor is it even measured on a dyno. The drive train is rolled thru the trans gears until a 1:1 trans ratio and coasted down to a cruise rpm, then the throttle hammered to WOT from a rolling start. At least that's how they do it around here.

Tracking down a faulty component is not guess work at all. But you do need to know 2 things for the component, any component. First is its required input, second is its designed or requested output. Then you need to know how to measure those. If you have control over the above there is no guessing and no parts or $$$ throwing. Sometimes it's tricky to find or difficult to fix an intermittent problems because that requires careful thought. You can not judge the output without first verifying the input. It's that simple and you can get thru eating the entire elephant like that.

If 35fordrat brought this to me here's exactly how I'd go about it.
Bottom up - and this eliminates most guessing, time waisting, and tail chasing.
Most of all the frustration. Yes it takes time but its time well spent and gets the car on the road quicker.

1 - compression test
It needs to pass that with flying colors or there's no chance of it ever running correctly.

2- piston stop test
This verifies the timing marks as correct and those marks are very important later.

3- battery voltage and charging system. Both at the battery and the ignition system. (I had to learn this one the hard way but I never forgot it )

4- grounds and especially at the distributor base. Check for any resistance thru the ignition system.

5- fuel pressure at the carb inlet/s

That ^^^ eliminates all the ghosts and some solid troubleshooting can be done if it all passes.

Next would be a road test with some basic testing equipment hooked up. A driver helps but it's not essential.
Vacuum gauge at manifold vacuum, a voltmeter at the coil, and fuel pressure gauge.
Watch the gauges for inappropriate fluctuations. If you see any they need to be addressed.

Next would be a general inspection of all tune up components, and a check of the distributor bushings. Replace anything that fall under consumable and designed wear items that Look inferior or used into their designed life expectancy. It's very important to use quality parts here. Test any vacuum pots with a hand pump & check that there is the correct source for them from the engine.

Run the standard tune up and adjustment dance. Set the timing, here I like to set the total timing. If its not correct at start and idle I now know and without any guessing that the curve is off and the dizzy timing mechanism needs addressed.

Road test it again - note any changes observed

Hesitation, flat spots, coughing, poor throttle response, black smoke require looking at the carbs. Tuning carbs is like going to the eye doctor- "what's better 1 (changeklickityflip) or 2 "

Since this is a reworked tri power with custom linkage, all of that needs to be checked out.
Does that linkage work like its supposed to? Are the bases modified correctly, are the end carbs butterfly's sealed, end carb bases should be thicker and the butterflies more of an oval and thicker gauge, no fuel drips. That may require dis assembly if things aren't right. Generally I find that any exterior screw ups are a good indication that interior screw ups are going to be present.

Following the intake runners back to the carb may provide some clues. Like I said before tri power manifolds can have some internal distribution variance. Lets say you found 2 plugs rich on each side and 2 plugs normal. Well since you've done everything above you'd know that the manifold is an issue.

 

So I made plates and covered the outside carb ports. Engine runs better. I am going to highway drive in the morning. If it's gonna run bad, this seams to be the time it starts.

 

Good move. You will get it sorted out. Follow what 31vicky suggested above. No doubt you'll get it running good. My setup is a home built one that runs very good. I got it tuned out and running real nice and didn't have to drill any holes anywhere. Do you have a way to take a video (with audio) of your highway test drive?

 

FOUND IT!! Test on the interstate was flawless. No hesitation, no spitting, perfect throttle response! Got to the off ramp light and the engine idled correctly. Took off from light and acceleration was perfect. Yesterday, when I removed the outside carbs to put the plates on, I noticed black rings in the carb bores. It appears that the rings may be keeping the butterflies from closing all the way. I also noticed some gunk in the primary carb filter (line side). I cleaned it out of course. Also, do the Venturi gaskets look correct for the secondary carbs?

 

That looks like that brush on sealer stuff. I would clean it off and make sure the butterflies are centered and close as good as possible. Hold them up to a light source to see any gap and try to adjust it out. Your throttle plates look to be tri-power plates with thicker butterflies which is good. You should be able to get them to close enough to tune your motor to run great. My set up has standard base plates and yes they don't seal perfect but I'm still able to get it tuned out to run very good. What jets are in the secondary carbs?

 

35fordrat, those are the bowl to plate gaskets and they look like they are doing their job.

 

I don't know the spec on the jets. How is the best way to find out?

 

You can't always go by the number stamped on the jet. Best to measure them. I have several sets of torch tip cleaners that have a smooth section at the ends. I use them to measure jet size. Just see which one slips into the jet and measure with a caliper. At this point maybe you should just clean up the secondary carbs and take another drive to see how things go. At least now you know the primary is good and if it doesn't run right, you know its for sure secondary carb related. In other words try do make one change at a time then test. That way you'll know what the problem was when everything is good.