Tune-Up Turns Up A Problem - Same One That Killed Millions Of Cars Back In The Day 

Why not just disconnect the auto choke and hook up a manual choke cable?

When I worked at a Dodge dealership in the 70's and early 80's, plugged crossovers was a common problem. On Chrysler products, the crossover has to be open and the exhaust damper has to function correctly or the choke will never fully open. We cleaned many intake manifolds and rebuilt many exhaust dampers. It seemed to be worse on the newer engines with EGR. A rule of thumb was that if you touch the intake around the choke with a fully warmed engine, it should leave a little skin.

Tony gets it - it's the *stories* that go along with each and every one of these old cars that make them matter, make them interesting, make us love them. The history of each are what makes this a true hobby. - Ed on the Ridge

Years ago, when I started off in an engine machine shop, I had to tear down the engines to be prepared for overhaul. I know exactly what Uncle Tony's referring to when It comes to those passage ways basically becoming a black diamond. I Would just toss them in the big oven and literally bake them overnight @ 750⁰. When I came in the next morning they would be still pretty warm. Then the carbon just basically turned to powder. So it's not real bad to clean them but still a pain. Thanks for sharing!

I blocked off the exhaust crossover on my ‘70 Charger with the aluminum Edelbrock Six Pack manifold. Worth a few HP, and then installed a manual choke.

Had that exact problem, solved with a manual choke cable, easy peasy.

Most of us, in those days went to manual control. It only cost $2 and solved the problems. In 1970, I took apart a choke on a '63 Chevy 283 that had been assembled backwards at the factory(choke off when cold and choke on when warm) or sabotaged at the dealer. Ten minutes and it was working fine. Good Luck, Rick

Manual choke even easier than finding a new manifold. A small four barrel makes it run so much better even if you arent looking for more power. I had the same setup on my old 318, threw away the stock carb and replaced with a junkyard Edelbrock . It ran better at idle, started easier and had more power. I get keeping things stock but sometimes its just too stupid to do.

I remember back in the 90s watching my dad do the same thing with a infrared thermometer that looked like a space laser. He used to tune carbs by header temp and smell. Really glad you're putting this info out there as these seem to be the more arcane tricks most people don't know.

UT, I'm glad to hear about keeping the cars history intact. The scribbles ARE part of the cars life story. I have a 58 year old, inaccurate tach mounted with an exhaust clamp by the original owner of my cherished 1965 GTO. I'm also leaving it as part of the cars history and nod to the original owner.

This and the previous video is why I love this channel. You’re the best, Uncle Tony.

I always ran a manual choke when I blocked off the heat riser on a hot rod

Back in the day I cleaned out dozens of 318/360 heat passages on those things. Being in Canada, at -30f i did about 6 a week. I have seen the whole carburetor frost up, inside and out, especially when it was humid and cold, with the complaint "it keeps stalling" or won't idle when it's cold and damp.

Back in the day we'd cut up a coffee can to create block off plate for the crossover passage in order to keep the fuel/air charge cooler. Our Holleys had manual chokes anyway.

If I had a dollar for every hour I've spent chiseling carbon out of Mopar manifolds, I think I could buy another old Mopar. Then I could spend more time knocking carbon out of that one.😆

Stuck a manual choke on my '69 340. Solved. Now if I could only keep the eddy's fuel bowls from evaporating away after the car sits it would be perfection.

Having worked as a Emission/driveability tech back in the the day i ran into this problem a stuck heat riser valve in the exhaust was a major player in this i dont know how many of those i have replaced but it was a lot ! keep up the good work Tony !!

That alternator belt is loose. I solved the choke problem on my cars. I removed the damned things. I live in Phoenix, AZ, where chokes are not needed. Pump the pedal a couple of times, and the engine will start right up. I always warm up the engine before taking off. I have never believed in putting a load on a cold engine. EFI is more than 10 times more complicated than a carburetor, so there are a lot more things that can and do go wrong. The last several years I worked as a professional mechanic for a large government fleet department, I had to deal with thousands of check engine lights. Automatic chokes have always been an issue, but they are a simple and easy problem to get rid of. Either get rid of the choke altogether, or use a manual choke.

Never had that issue. I substitute one quart of Marvel Mystery Oil every oil change and put 4 oz of MMO to every 10 gallons of fuel, every fill up, for years, on all my vehicles.

maybe it has Intake Gaskets that are blocking that passage off.

Amc with the 2100 and 2150 carbs. Have a plate bolted to the side of the choke thermo spring with those black housings. That plate holds the heatercore hose directly from the intake/thermostat housing area. So this helps heating the choke up very quickly. With this. Ive never had issues running my 360s with rusted out broken heat tube risers on the intake. It heats up very quickly within seconds. Those heat riser tubes under the carb in the intake . Also helps create vapor lock. Some guy will take the intake off and block it off to fix vapor lock

I have a 1970 truck 318 in my Barracuda that has a water passage under the carb, rather than exhaust gas, so i had to go manual choke. Best part, its a forged crank w/ sodium valves!

Scribbles on the gauges...perfection. I agree, it fits the car and is part of its history.

That style choke uses a 12V wire to operate in addition to heat provided by the exhaust crossover in the intake manifold. There is a heating element next to the bimetallic spring that operates the choke. The post is still there, and the wire is broken off. A switched 12V power source will open that choke.

Uncle Tony, in the late 80's and early 90's i cleaned alot of those intakes. Theyd give those crappy jobs to the kids in those days! Manual choke is way easier 😅 Cheers from Junk's Automotive Indiana USA

This is why I always use a Manual Choke and completely despise an "automatic" choke and I'll go so far as to say that 90% of all classics you get your hands onto will have this issue. A machine shop can knock out that cross-over and it's not that bad on price, but it's included in all the rest of the bill when we take them an engine to make ready for assembly. Good stuff as always UTG.

Shelve that manifold with other antiques. Check the head ports place a performer manifold and carb. Yes I know it's a daily driver. But this engine deserves it make it happy!

Very true about blocking any manifold heat for an engine that will see a track. Cooler air is denser, which means more power, and in racing, you want to WIN by an inch, not lose by an inch. On a street engines, you WANT manifold heat, as a warm manifold means a stable air/fuel charge - in the winter, the gas will tend to fall to the walls of the manifold at lower speeds until you have been driving for quite awhile.

My '71 Fiat 124 had a factory manual cable choke. It worked perfectly. All my old motorcycles have manual chokes. Its somehow more satisfying when you have to interact more with the machine.

Someoe mentioned using a manual choke, good idea. I like being in control of such things!

The previous owner of my ‘41 Chevy tied up the broken end of the windshield wiper with a bit of string. This truck never sees the rain, so I have left the wiper and string as is. It’s part of the truck’s history.

Kathy is waiting for this car to be done so she can drive it. Tony is taking his time.

318s and 360s were terrible for that. I have done countless de-carbons on those, usually having to use chisels and old screwdrivers to chip out the coal-like carbon. Don't miss those days.

I ran into that with a 283 years ago. As it was my daily driver and already had an old wore out Rochester 4GC four barrel carb, I did the street aluminum intake and a 390 Holley w/ vacuum secondaries along with a manual choke. Problem solved, the Nova ran great and got good mileage. Those old 4GCs at that time were very hard to find, which is why I went with the Holley.

If the intake passage is clogged, so are the passages in the heads! Just changing the intake won't resolve that.

"a vicious circle" The algorithm brought me here after the previous video you mentioned. Thanks again.

Back in the late 1970's and 1980's I took many intake manifolds off on Chrysler engines because of what you are talking about I would clean the passage in the heads and I would take a small stiff rod and run it through the intake manifold and put the car back together and send it down the road as alot of people in my area had Chrysler products whether trucks or cars and here in southwest pa it gets cold in the winter so they had to have the choke working right!!!!! There was one Chrysler New Yorker 440 engine that wouldn't start one cold day and I took the Tow Truck to this Lady's house and put the jumper cables on it and I could smell ether bad, so I asked her Husband how much ether did you use and he said very little so I started the car and heard a boom and tin rattling and when I looked under the hood it blowed both valve covers off the engine so I towed it to the garage went to the junkyard and got valve covers and put them on and started the car and everything was ok, the car ran great!!!!!!

Tony, I had a 360 in a '74 Ramcharger that would turn the carburetor into a block of ice. It actually would build up 3/8" of ice in the summer... until the intake was changed. I could warm it up and shut it off for about 15 Minutes and the block heat would thaw out the carb. then it was pretty driveable.

Looks like a new camera or uncle kathy playing with the lighting in the editor. Nice! Looks good guys, nothin but gratefulness for basically free content!

Uncle Tony…..I cleaned the carbon on intakes when I was just starting out in a Dodge dealership. You remove the intake and heat the passage blocked with carbon with the acetylene torch, then turn off the gas and blow the oxygen on the carbon to accelerate the burn. It does smoke and stink up the shop, but they come clean as new. Working on cars 45 years ago was more enjoyable! Another quick tip: If you can hold your finger on the choke stat longer than the count of 3, it’s too cold 😳

My mother taught me my first mechanical lesson in the 70's when trying to warm start her Plymouth: "Put the screwdriver down the hole to open the butterfly valve." Thanks Mom.

Explains why my mechanic 35 years ago said I had to leave it overnight for a diagnosis. I started a different comment until you explained the conflicting advice to plug the heat crossover.

one of the other reasons it builds up is because of the ruff casting inside the cross over ports . I just plug off the ports and run a manual choke because the factory set up causes the carb to percolate durning the summer from the heat . If people wanted to spend the extra money they can send off the old cast intakes to a place that pumps in a putty with grit in the ports that goes through and cleans and smooths out all the ports . Cant remember the correct name but saw it several years back in a mopar car magazine

Manual choke, problem solved. I always run manual chokes.Manual choke kit, $20, New /Used intake $80-140.

Gold wing. ! You lucky dog . Has jar took a ride yet . Remember she is a big part of the uncle Tony saga !

I'd forgotten about having this problem back in the sixties. In every case, they were big sleds that never saw 3500 rpm or full throttle.

Add a manual choke knob to pull it open..

Maybe the intake gaskets are not correct and block off the passage. You have to do an autotopsy.

My first car 72 Nova 250 6 3 on tree I put a manual choke on. Pull it as you press gas down once and every time first crank vrrrooom . Funny nobody could start that car without flooding it.Best car I ever had .

Yep . As I recall , they were called Heat Risers ? Along with what you mentioned , the cold bottom of the manifold doesnt help vaporize the fuel / air mixture beforehand . When guys ask me what I like best between carburation and electronic fuel injection ? I say that each has a purpose for a given situation ...that avoids the argument . Using the Jeeps , the cars were limited off road . If the hill was too steep , the carb worked against you due to the float . Injection has no such problem .

Only thing I would do is fix the rust issues and drive it. It’s definitely a cool old car!

Tony...somewhat off topic, but I see this car has a clear glass fuel filter, of the type that can be disassembled for cleaning...PLEASE remove it ASAP and replace with a metal housing filter. I had a woman with one of these filters on a fake MG with a Volkswagen engine. She complained of a gas odor. I opened the access hatch and a QUART of gasoline poured out!!! The pot metal threads holding the filter together failed just enough to create a leak at the ends, but still passed enough fuel to keep the engine running. She was a frog hair away from a catastrophic engine fire!!!

Rev the motor up and slam the choke down a few times that might get the idle screws to respond better...I have no clue why this works on a carb but it does. Jamie did it on an Eldlebrock thet other day.

I once came across this fellow having trouble with his "hot" "63 Vette. He installed a rebuilt engine but could not get it to run cool around town; on the road OK but otherwise ran hot. Spending days on his problem, he changed the water pump, radiator, thermostat etc but no help. Showing me the problem, he started it up cold and within a short period, the engine was radiating so much heat, you had to back away from the engine. Looking down at the exhaust manifold, I spotted the heat riser and saw that it was installed upside down so as the engine warmed up, the exhaust gases increased into the intake manifold cross-over...

I love these "basics" videos! It's stuff I don't know, or have forgotten.

Yes, that was a common problem, but mostly a Mopar thing because of their choke functions. You also neglected to mention the other piece of the puzzle, the heat riser valve that makes more of those hot exhaust gases flow through the intake. I just freed one up on an old 318. It also has a thermal spring that opens it up as the engine warms up so you don't boil the gas in the carb. For all of you that think a manual choke is the solution, you don't know how to set up an automatic one properly and you don't know the pleasure of driving a car with one that works as it should.

Manual chokes were so much better. For many years, I would reach for the choke, automatic chokes sucked.

Great video and great explanation, I just install manual chokes on my old cars. Kinda off subject kinda on subject. My son once wrote I love Dad inside our china closet , My wife discovered it and showed it to me and asked what we should do. I said nothing that’s awesome!!

Another great vid and a very valid topic no one ever talks about. But in my experience working in an automotive machine shop, i have to disagreed that the intake is a throw away. i would chip out the big pieces clogging the entrance ports of the cross-over, remove the splash shield under the intake, then drop it in the hot tank. the intake comes out spotless every time.

Dear god please check the heat riser valve before removing the intake manifold.

I once had a plugged intake manifold from a 2 barrel 318 hot tanked in a bath of chemicals for a few hours and came out spotless. Simpler than changing the whole intake.

To keep the choke functional i have only blocked off the drivers side crossover.

Ford small blocks PUs had the same problem. One of the secrets of small block Dodges PUs was keeping that passage clean.

Check the heat riser valve also!

On these cars & all the ones I've owned that had carbs, I used a manual choke-always. No problems. If it came with an automatic choke, it was switched to a manual. It's not that hard to do. But your video is right on the money.

Those SB Mopars are famous for the passages filling with carbon. My old friend Jim used to soak the passages with diesel fuel and ignite the carbon. It would burn slowly and within a couple of hours clean as a whistle!

When I was a teenager and the only dirt bikes were 2stroke and when they gummed up the exhaust badly with carbon and I can't remember what we used to soak out the carbon buildup in the pipe because as teens no one had any money to buy anything but gas and Tyres 😅

Was a dodge dealership in a little town in Virginia called Gretna, when they went out of business one of the mechanics leased the building and ccontinued to service cars that were sold new there, also sold lawnmowers ,weed eaters, chain saws, we used to do tuneups, and preventative maintenance, like putting in timing sets I've pulled many intakes and cleaned out the crossovers, a small chisel would break through it initally, it got easier after that, but I'm with you ,iwould toss that intake and at least go back to a 72 or older that had no egr or electrically assisted choke,which will look more stock

At 9:15, I think you mean a "runaway condition", also can be called a "positive feedback condition". As an engineer I have encountered runaway failures that need redesign to prevent. Sometimes designers know of an issue but they don't fix as it is expensive, and the issue will not be noticed until later life, so managers say ignore it. A great video explaining this issue. I am amazed on the things I still do not know. Thanks. Cheers Tony!

Love the scribbles background lore of the ‘cuda! Also sounds like a similar problem on a rule injected Nissan maxima I had with the EGR piping becoming completely clogged. Ran terribly when I got it but it ran better and better the longer I had it!

Never have I EVER heard this exhaust carbon buildup being an issue for choke issues. Thank you.

This is the material that makes this channel interesting. Tony is a great teacher of old moparology

*"Vicious Cycle!"*

Tony, spend your time repairing the rust on the car for when you sell it... Do good quality work through out the entire car. etc etc. I'm looking forward to purchasing that car for a future project. 🙂

That intake may have been a throwaway 40 years ago, but not today. It is NOT that hard to clean out the hardened carbon. I’ve done it on three 318s and it isn’t that difficult. But it makes a massive improvement in driveability.

Air cooled VW's are very prone to the carb/intake heat runner getting clogged with carbon. Gotta take it out and heat it with a torch, then run an old clutch cable through it while chucked into a cordless drill. Works almost every time!

With the cast iron intake manifolds, I could always fire up the torch to get the carbon out of it. It makes lots of fun sparks, too. Just do it outside, the hell away from everything else. Use appropriate shielding or do the hot ember dance. The aluminum manifolds weren't as easy.

That's a big temperature difference. I like how you use a fancy digital IR thermometer to pin point an old problem. I look forward to the fix.

What about the adjustment on the choke pull off rod? It should be able to open the choke fully after a few blips of the throttle. In the summer you just need the choke to start not to stay on.

Love how you got your name for Scribbles!

I daily an 86 Nissan D21 with Z24i engine. I have hot start issues. The tbi seems to be over fueling on hot restarts. I know it could be a few things I just wanted to share some of the weird stuff. The coolant runs through the tbi and it has a wax pellet choke. It has duel sparkplugs with a flow thru hemi head and is cam on bucket with adjustable tappets. People look at me funny when I try to tell them about it.

I had a 69 Charger with a stock 318. It DID NOT have an electric choke of any kind. It was set up the same way as Tony's Barracuda, and it worked fine.

Scribbles was almost a Write-off 😮 👀. This is why routine maintenance is good thing on just about everything & anything.

I put manual chokes on my 68 and my 74 Plymouths back in the day. My brothers 65 Econoline came from the factory with one.

Outstanding information Tony. I'm dealing with a 76 gm 250. What a pain in the arse it has been.

You are looking for the term, "Vicious Cycle."

Awwww!!!! I can see you have a soft spot for the kiddos, Uncle Tony!!! Right on man!!!!

When you find another intake manifold do a video of the carbon build up inside the heat cross over Uncle Tony.

Back in the day, I cleaned out many of the intake manifolds that caked up with carbon in the heat crossover passage. Used a hammer and small chisel. Once done, the choke functioned as designed. An intake manifold was too expensive to throw out if it could be saved. Typically happened on Chevy small blocks.

I couldn't find books in the library to help me with these problems. Now we have youtube.

Or has gasket with the heat crossover blocked off which I bet it has. Rarely were crossovers blocked off by soot.

THIS, is why I’m here.

Thank you for this! My 62 Bel Air which is a 235ci has this exact problem and was struggling to figure it out.

I love the scribbles! I would pay extra $$ to buy something with that personality. Much love UT and UKB

every day we learn something new, old school style,,,

One more thing for me to check on my 318 pickup. Seems like I could never get the choke to stay adjusted.

My carb'd jeep 6 has an electrically heated coil in the intake, I have a new respect for it

i know someone with a motorhome with the same symptoms, ill have to go back and see if this is whats going on. thanks tony

As a mechanic in the 80's I had a car come in with a 440 and anti-foul plug extenders on all 8 cylinders. It had rings so bad it would use a quart of oil a week. I would have loved to tear it down and seed how bad it was inside.

Not an issue on any of my classics as they have SUs with manual chokes, but I sure appreciate the information. Thanks.