Monojet blues Redux

[MS66]

Yet another episode of the monojet saga
Good Morning.
Three weeks ago, I acquired a fairly decent all original 1968 C-10 long bed farm truck with factory 250 L6, three speed, and a manual choke monojet "crab", #7028011.
It would start and run with the choke nearly closed just enough to limp it up on a trailer. One ear of the carb was broken where the baseplate bolts to the main body. When looking for a replacement carb to rebuild I found out that '68-69 used this carb. Before I sunk a small fortune into a monojet just to see how this engine runs with factory carb, I cleaned the parts squeaky clean, then stuck the broken ear back together with JB Weld "steel". Success. I put it together and it ran and idled great. Going down the road has a terrible part throttle lean surge that a little choke fiddling helped get past. The patch gave me a couple weeks to run it before it let go, which is more than I expected.
I'm still searching for a good 7028011 carb to work with if I find one reasonable, but I'm not against doing a swap to a better carb that is easier to tune with more drivability. Being super budget strapped is an understatement so putting the money towards a better end result sounds good to me.
If anyone in here has that carb, or a good monoject to get me rolling while I'm putting out fires all over this truck, please holler.
Now on to the main question, has anyone in here used the chy knee nonojet sold on the auction site, and how does it work for you? It looks like a copy of a later version somewhere around '72-'78.
Preciate it.

[Yamariv]

Not sure what I'm missing but why don't you get a $30 rebuild kit for the monojet instead of buying a cheap Chinese one?

When I got my truck, it barely ran/would only idle. I rebuilt the monojet which was pretty simple to work on and now the truck runs flawless. I'm actually blown away how well it runs in all situations, almost like it's fuel injected

[RustyPile]

Originally Posted by Yamariv

Not sure what I'm missing but why don't you get a $30 rebuild kit for the monojet ...............

I think this will answer your question..

Originally Posted by MS66

.............. One ear of the carb was broken where the baseplate bolts to the main body. .......The patch gave me a couple weeks to run it before it let go, .

[MS66]

Originally Posted by RustyPile

I think this will answer your question..

Haha, thanks Rusty! We must have been typing at the same time.
Dude, love your avatar truck! Same color as mine. Are you the one that did the Holley two barrel swap on a '68 250?

[RustyPile]

Originally Posted by MS66

Haha, thanks Rusty! We must have been typing at the same time.
Dude, love your avatar truck! Same color as mine. Are you the one that did the Holley two barrel swap on a '68 250?

Thanks for the compliment..
The truck's what I'd call a 50 footer.. After buying the truck from a resto shop, the PO let the truck sleep under a pecan tree for the better part of 15 years.. The paint shows this neglect..

As for the two barrel swap, No, not the one documented here, but I've done all kinds of carburetor swaps.. Like you, I've been doing carb work for over 50 years..

[MS66]

Originally Posted by Yamariv

Not sure what I'm missing

Maybe this is what you're missing; "One ear of the carb was broken off where the baseplate bolts to the main body."
I've been rebuilding carburetors for 50 years, consider myself to be above average at tuning. Thanks for reading.

[Yamariv]

Ahh, missed that part! I'd buy a real Monojet and rebuild then.

[Jason Banks]

I have a 1968 with a straight 6 and monojet also.

For several years now, I have had a "saved search" on eBay for carburetors....here's a link

https://www.ebay.com/sch/i.html?_nkw...2%29&_svsrch=1

I have bought many, most in the sub $50 range. I've never got anything much better than extra parts. I haven't tried to run many of them. Even one that was a NOS Reman didn't run better than the one that come on my truck, that the guy I bought it from had just rebuilt.

I'd try to pickup the cheapest you can just to replace the broken part of yours. Get a rebuild kit and just use what you need to get it going and try to improve from there. Or, if you have time try out the full rebuild. They're a very simple carb.

I'm not sure what the deal is with the "Autoline Carburetor C9044" Rockauto has it listed and Autozone has it listed as a reman for the 1968. Over the years, it goes in and out of stock. I've often been tempted buy buy one and see how they run, but I've gotten pretty good at keeping what I have going.

[jumpsoffrock]

Originally Posted by Jason Banks

I have bought many, most in the sub $50 range. I've never got anything much better than extra parts. I haven't tried to run many of them. Even one that was a NOS Reman didn't run better than the one that come on my truck, that the guy I bought it from had just rebuilt.

I have an almost identical story to this for my Ford truck. I was really surprised and irritated at how hard it can be to find a usable use carb/core for sale.

[dmjlambert]

I suggest give a call to National Carburetors and see what they can do for you regarding the broken ear carburetor you have. Perhaps they have that part or can make it, and when they rebuild your carburetor they can replace it. I ordered a 1969 Quadrajet from them, and when I called them to talk about what they would send me and had a discussion with them, they offered to build a more modern Quadrajet from later year (1985-86) with linkages compatible with 1969, so I went that route. I like it quite a bit and the later model year carburetor was less expensive and had an electric choke.

[MS66]

Hey, sorry I didn't post a follow up on the Monojet until now. Paying $300 plus for a carb from National Carburetor wasn't an option.
I searched for weeks for a 7028011 carb for this engine. I found 3 of them, but not in the best condition for what they were asking for them, then no one would pop the top off of it to show what the bowl looked like before I paid top dollar for a pile of unusable oxidation.
At one point, after trying two different carbs off of "running" 250s "when they were pulled" that didn't run worth talking about on my truck, I had just about given up getting the truck ready to ride down to the MS. gulf coast for the annual Cruising the Coast week.
Another week went by when I finally found the exact carb that came on this engine. It looked promising. The seller graciously popped the top off and took pics of the bowl before we agreed on a price. We did the deal, ended up being around a C note, shipped. Another week goes by waiting for it to get here.
After tearing it down and some judicious cleaning it went together with the parts from my original carb. It fired up and ran like a top with some fine tuning.
Yes, success, a carb that worked. The 250 was stronger than ever now, ran like it should. That changed everything and got me determined to finish it for the cruise week. With the help of a friend, we built an exhaust system for it that exits right at the front of the rear wheel opening. I put a high flow cat off of an Impala SS in, then a turbo muffler welded to the cat, then routed it out in front of the rear tire. It is very quiet yet flows plenty air. The cat took the nasty raw gas smell out of the spent gas, purrs like a kitten, and actually boosted midrange response. This truck runs sweet.
That's when the headache with the fuel tank reared it's head. I had recently replaced the rusted out original tank with one I bought from a local rod builder that he had taken out of his wife's '72 C10. The inside of the tank looked clean enough to just blow out with the shop vac. What you couldn't see was the white dusty oxidation further up the walls of the tank. I was running it with less than half a tank when I was setting up the carb, but as soon as I went over half up past 3/4 tank is when it began to put a fine silty sediment into the carb. 3 more days of fighting that, ended up with a large Fram canister filter going into a clear glass filter, then into the original paper filter in the carb. All of this was after the mechanical fuel pump. Finally, rolling again. The paper filter in the carb filters much better than any filter I've had on it, so I keep a stash of them in the glove box. So far so good, I should be good until all the mess is gone out of the tank.
I was a few days late leaving on the trip, but it all went without a hitch. Truck ran flawlessly. I stayed on two lane and rarely got over 55 mph. The total mileage was 553, used roughly 30 gls of gas. Gas mileage was much better than I expected for the 250. I'm running 31x10.50r15 Wrangler ATs on the rear. That helped tame the 3.73s. All in all I'm super happy with the farm truck. Will be working on doing a DB/PS conversion soonly!!

[D.B]

Originally Posted by MS66

Hey, sorry I didn't post a follow up on the Monojet until now. Paying $300 plus for a carb from National Carburetor wasn't an option.
I searched for weeks for a 7028011 carb for this engine. I found 3 of them, but not in the best condition for what they were asking for them, then no one would pop the top off of it to show what the bowl looked like before I paid top dollar for a pile of unusable oxidation.
At one point, after trying two different carbs off of "running" 250s "when they were pulled" that didn't run worth talking about on my truck, I had just about given up getting the truck ready to ride down to the MS. gulf coast for the annual Cruising the Coast week.
Another week went by when I finally found the exact carb that came on this engine. It looked promising. The seller graciously popped the top off and took pics of the bowl before we agreed on a price. We did the deal, ended up being around a C note, shipped. Another week goes by waiting for it to get here.
After tearing it down and some judicious cleaning it went together with the parts from my original carb. It fired up and ran like a top with some fine tuning.
Yes, success, a carb that worked. The 250 was stronger than ever now, ran like it should. That changed everything and got me determined to finish it for the cruise week. With the help of a friend, we built an exhaust system for it that exits right at the front of the rear wheel opening. I put a high flow cat off of an Impala SS in, then a turbo muffler welded to the cat, then routed it out in front of the rear tire. It is very quiet yet flows plenty air. The cat took the nasty raw gas smell out of the spent gas, purrs like a kitten, and actually boosted midrange response. This truck runs sweet.
That's when the headache with the fuel tank reared it's head. I had recently replaced the rusted out original tank with one I bought from a local rod builder that he had taken out of his wife's '72 C10. The inside of the tank looked clean enough to just blow out with the shop vac. What you couldn't see was the white dusty oxidation further up the walls of the tank. I was running it with less than half a tank when I was setting up the carb, but as soon as I went over half up past 3/4 tank is when it began to put a fine silty sediment into the carb. 3 more days of fighting that, ended up with a large Fram canister filter going into a clear glass filter, then into the original paper filter in the carb. All of this was after the mechanical fuel pump. Finally, rolling again. The paper filter in the carb filters much better than any filter I've had on it, so I keep a stash of them in the glove box. So far so good, I should be good until all the mess is gone out of the tank.
I was a few days late leaving on the trip, but it all went without a hitch. Truck ran flawlessly. I stayed on two lane and rarely got over 55 mph. The total mileage was 553, used roughly 30 gls of gas. Gas mileage was much better than I expected for the 250. I'm running 31x10.50r15 Wrangler ATs on the rear. That helped tame the 3.73s. All in all I'm super happy with the farm truck. Will be working on doing a DB/PS conversion soonly!!

Wow, that is cool. Thats a long trip, 553 miles. Way to go.

['68OrangeSunshine]

Nice '68. Camper cap is cool. But why would you put a catalytic converter on a vehicle that wasn't designed for one? No state requires them for emissions on this Vintage.
Now you can't put ZDDP in your oil. Without the proper amount of Zinc, the Lifters will wear out the Cam prematurely.
It's your truck, but L6s run better with fewer complications.
I quit using a Monojet on my 292 in 1978. Offy intake, 4 Bbl carb, and Clifford headers. Not cheap then, but by today's prices that set up will cost a small fortune now.
The ''white dusty oxidation'' you mention is Tetra-Ethyl Lead deposits. A key metal-on-metal cushioning agent present in all American gasoline until about 23 years ago, when it was removed for environmental reasons.
I like the fact you have a proper White-Faced '68, West Coast Jr mirrors, stock rims, and an L6 motor.

[MS66]

Originally Posted by '68OrangeSunshine

Nice '68. Camper cap is cool. But why would you put a catalytic converter on a vehicle that wasn't designed for one? No state requires them for emissions on this Vintage.
Now you can't put ZDDP in your oil. Without the proper amount of Zinc, the Lifters will wear out the Cam prematurely.
It's your truck, but L6s run better with fewer complications.
I quit using a Monojet on my 292 in 1978. Offy intake, 4 Bbl carb, and Clifford headers. Not cheap then, but by today's prices that set up will cost a small fortune now.
The ''white dusty oxidation'' you mention is Tetra-Ethyl Lead deposits. A key metal-on-metal cushioning agent present in all American gasoline until about 23 years ago, when it was removed for environmental reasons.
I like the fact you have a proper White-Faced '68, West Coast Jr mirrors, stock rims, and an L6 motor.

Wow, sometimes I wonder why I post things in public.
I post something feeling good about resurrecting an original farm truck from sure death in the condition it was in and heading into oblivion, then I get chastised by the guy that should be happy about it. WTF, sunshine you having a flashback?
I mentioned why the cat is on it, have you ever poked your head inside a camper shell full of gas fumes from corn fuel lately?
The tank is an aftermarket replacement tank about 6 years old, it wasn't even around when lead was a thing 40 years ago.
The wheels on the truck in the second pic on the beach aren't factory, only the 2 year hubcaps are at present.
Thanks for appreciation, and the vote of approval for keeping it real with your rant about the Monojet vs. a $2000 Clifford, Offy, Holley intake and exhaust system on your 292. You make me feel inadequate for keeping this one family, original 59k mile truck running.
BTW, am I supposed to be impressed with this comment; "I like the fact you have a proper White-Faced '68, West Coast Jr mirrors, stock rims, and an L6 motor." after the needless beat down you put on me? Where is the dick swinging emoji? smh

['68OrangeSunshine]

Originally Posted by MS66

Wow, sometimes I wonder why I post things in public.
I post something feeling good about resurrecting an original farm truck from sure death in the condition it was in and heading into oblivion, then I get chastised by the guy that should be happy about it. WTF, sunshine you having a flashback?
I mentioned why the cat is on it, have you ever poked your head inside a camper shell full of gas fumes from corn fuel lately?
The tank is an aftermarket replacement tank about 6 years old, it wasn't even around when lead was a thing 40 years ago.
The wheels on the truck in the second pic on the beach aren't factory, only the 2 year hubcaps are at present.
Thanks for appreciation, and the vote of approval for keeping it real with your rant about the Monojet vs. a $2000 Clifford, Offy, Holley intake and exhaust system on your 292. You make me feel inadequate for keeping this one family, original 59k mile truck running.
BTW, am I supposed to be impressed with this comment; "I like the fact you have a proper White-Faced '68, West Coast Jr mirrors, stock rims, and an L6 motor." after the needless beat down you put on me? Where is the dick swinging emoji? smh

OK. Sorry if I hurt your feelings. I was only concerned with the Catalytic Converter issue. Old School engines [w/o roller-rockers] need ZDDP to minimize friction that can flatten cam lobes in your engine. The Zinc from motor oil in the last 30 years has been gradually weaned out because the platinum in Cats is ruined by Zinc. You have to go out of your way to find ZDDP. Valvoline VR1 has a proper dose of it. Riselone [sp] sells a ZDDP additive, STP for 4 cylinders has ZDDP, but off the shelf autoparts store motor oil does not have Zinc any more.

As for the L6 High Performance parts spiel, I didn't mean to brag. I had no idea that stuff had gotten that expensive. I ''squandered'' a student grant at the speed shop, 45 years ago. Probably spent about $300. My goal was to make the Factory 292 run a lot faster. I lived 10 miles north of campus, and had to make a left onto a high traffic road [US 89] into town. Miners from Mammoth had gotten off the night shift, and by the time they were in my neighborhood, had time for about 3 beers and built up a good turn of speed.
It was Speed or Die.
When the school administrators learned I hadn't bought encyclopedias and pencils, they weren't impressed. To them it was all Chrome and Raccoon tails.
Anyway my investment paid off, as I was able to get the Offy intake and Clifford headers hot-tanked and bead blasted [headers repainted] after a 25 year run, and mounted on my 2005 292 rebuild. The Holley R8007 390 CFM 4160, did not last, and I had to buy an Edelbrock 1404 500 CFM carb.

I was wrong assuming you had a vintage tank with TEL deposits. The white spots are definitely corrosion.
Hard to asess a fuel fume issue 3 quarters of a continent away. Could be you're running too rich. Could be there are leaks in your exhaust pipes. Could be the tailpipes exiting before the rear wheels are not ideal for an enclosed cap above them. IDK.

Sorry for any perceived slight or insult. Not my intention at all. This website is generally positive, and all the members usually get along and help each other. Ones that don't get banned.

Enjoy running your '68, and don't listen to me.

[54blackhornet]

MS66 you did good ! That pickup looks awesome. I don’t believe Sunshine was trying to hurt your feelings one bit ! But installing a Cat on an older engine is out of step with us older folks. You really should not have much of a fuel smell if everything is working correctly. I have a non EEC C/20 and never smell anything. I have replaced all the rubber fuel lines and had the DuelJet rebuilt. Anyway I really appreciate you sharing the story of bringing another vintage pickup back to life. Do you sleep often in the bed ? I see a comfortable looking arrangement..Jack

[MS66]

Originally Posted by '68OrangeSunshine

OK. Sorry if I hurt your feelings. I was only concerned with the Catalytic Converter issue. Old School engines [w/o roller-rockers] need ZDDP to minimize friction that can flatten cam lobes in your engine. The Zinc from motor oil in the last 30 years has been gradually weaned out because the platinum in Cats is ruined by Zinc. You have to go out of your way to find ZDDP. Valvoline VR1 has a proper dose of it. Riselone [sp] sells a ZDDP additive, STP for 4 cylinders has ZDDP, but off the shelf autoparts store motor oil does not have Zinc any more.

As for the L6 High Performance parts spiel, I didn't mean to brag. I had no idea that stuff had gotten that expensive. I ''squandered'' a student grant at the speed shop, 45 years ago. Probably spent about $300. My goal was to make the Factory 292 run a lot faster. I lived 10 miles north of campus, and had to make a left onto a high traffic road [US 89] into town. Miners from Mammoth had gotten off the night shift, and by the time they were in my neighborhood, had time for about 3 beers and built up a good turn of speed.
It was Speed or Die.
When the school administrators learned I hadn't bought encyclopedias and pencils, they weren't impressed. To them it was all Chrome and Raccoon tails.
Anyway my investment paid off, as I was able to get the Offy intake and Clifford headers hot-tanked and bead blasted [headers repainted] after a 25 year run, and mounted on my 2005 292 rebuild. The Holley R8007 390 CFM 4160, did not last, and I had to buy an Edelbrock 1404 500 CFM carb.

I was wrong assuming you had a vintage tank with TEL deposits. The white spots are definitely corrosion.
Hard to asess a fuel fume issue 3 quarters of a continent away. Could be you're running too rich. Could be there are leaks in your exhaust pipes. Could be the tailpipes exiting before the rear wheels are not ideal for an enclosed cap above them. IDK.

Sorry for any perceived slight or insult. Not my intention at all. This website is generally positive, and all the members usually get along and help each other. Ones that don't get banned.

Enjoy running your '68, and don't listen to me.

Right on. Thanks for the reply.
I put it back as close to how it was designed to run as possible so I can live in '68 again. The speed parts comments aren't relevant to what I'm doing on this truck is the reason I hit you with that. I've modified (ruined? LoL) everything I own for the last 50 years, now I want to enjoy them like they were designed, and how they were meant to be driven. For all the time and BS I went through to make this thing back to factory I could have done an LS swap. Crazy as hell ain't it.
I'm well versed in what ZDDP is and why we need it. No amount of ZDDP is going to ruin this cat the way I drive, it won't see 2500 miles a year. Plus the fact this engine is tight as a drum, registering 135-140 on every hole. The engine is mint, truck was never abused. The original oil bath breather has to be the main reason for the good ring seal and no guide wear.
BTW, don't think I haven't been down the 6=8 rabbit hole before and certainly have the same thoughts again. Right now, I'm loving the way this truck runs and operates.
Later sunshine... lol

Originally Posted by 54blackhornet

MS66 you did good ! That pickup looks awesome. I don’t believe Sunshine was trying to hurt your feelings one bit ! But installing a Cat on an older engine is out of step with us older folks. You really should not have much of a fuel smell if everything is working correctly. I have a non EEC C/20 and never smell anything. I have replaced all the rubber fuel lines and had the DuelJet rebuilt. Anyway I really appreciate you sharing the story of bringing another vintage pickup back to life. Do you sleep often in the bed ? I see a comfortable looking arrangement..Jack

Thanks man, I'm loving it!!
I know. He went off on the cat right away. I know why he did, because EVERYONE cut them off their trucks first chance they got to get more performance and get rid of the rotten egg smell. lol
Believe me, it is sort of a backwards way of thinking on these old trucks, but it's working out perfect for me. I do stuff like this that gets people to think. So far every one of my buds have liked the results. Even though, just like 95% never would have thought to do it. The truck never ran, "smelled", or sounded better.
When I got the truck it didn't have any exhaust on it. First thing, I had to pull the manifolds off to machine the two broken flange studs out of it. I'm still getting metal slivers out of my fingers from the carbide end mill I used to cut them out with.
The bed is comfortable for me. I like firm bedding, works out great. I just put all that together the day I left going to the Cruise down on the coast. I kid you not, I found the camper cap in a farmers field the day I was supposed to leave, two Saturdays ago.