The Stovebolt Site Forums The Shop Area Engine Shop 1957 6500 fire truck w/261 - carb questions

Hi everyone!

New member from Sweden here, thanks for letting me join!

I recently purchased an old fire truck, a -57 Chevy 6500 heavy duty truck that has a 261 engine. The truck has been sitting for a long while, so I'm slowly working my way towards bringing it back to life. I have managed to get it running ever so briefly, but the carb is being... Uncooperative... I have tried taking it apart, cleaning it thoroghly and putting it back together, but sadly it had little effect.

Now, as I said I'm from Sweden so local parts are pretty much nonexistent and buying overseas tends to be costly with shipping and import taxes adding on to the initial cost of purchasing parts... I'm on a pretty tight budget as it is when it comes to this project, so I was wondering if anyone has tried any of the many chinese clone budget carbs available on Ebay and Amazon? I have seen some of them available from european sources which greatly reduces costs compared to buying and importing genuine goods from the USA, almost to the point where it becomes more economical for me to buy one of these clones rather than investing in so much as a rebuild kit for my original carb... Assuming of course that the chinese copy cats work worth a darn.

Here's an example of carbs I've been looking at:
https://www.amazon.com/Partol-Carburetor-Chevrolet-Engines-Barrel/dp/B073W9QM3K/ref=sr_1_1?crid=2GAQXCKA3VN7J&keywords=chevrolet+292+carb&qid=1671106300&sprefix=chevrolet+292+carb%2Caps%2C201&sr=8-1
From what I understand it's basically a chinese repro of a Rochester 1MV Monojet which were used on the Chevy 250 and 292 inline six engines, and I have heard that those are potentially worth considering as a substitute carb for my 261 engine.

So, what's the verdict? Has anyone actually tried one of these chinese carbs out, or are they generally regarded as trash and not even being worth the <$100 price tag? I have read a bunch of online reviews from people who have bought these clones, as well as watched a some youtube video reviews, and many of the people who took the plunge actually seem to have been pleasantly surprised by what they got. At least considering the price tag.

I'm not expecting them to be as high quality or perform as well as the real deal, but to me the main thing is getting my hands on something that will work better than what I already have without breaking my economy. If these chinese carbs at least provide decent value for money they might be worth to consider, at least for me. Any thoughts?

Also, apologies if the question itself is considered heresy. I assure you I mean no disrespect, I'm merely trying to learn more and explore what my alternatives are when proceeding with this project.

Here are a few pics of my truck in case anyone it interested:
www.youtube.com/watch?v=t6sOZhWUld8

Well met!

/Anton

What model carburetor is your original? If it's a Carter, you will be better off obtaining a correct, quality rebuild kit from The Carburetor Shop.

www.thecarburetorshop.com

I am currently battling problems with a Chinese knockoff carburetor on a 1966 Mustang. Utter crap. Float filled with fuel in just a year is one example of the poor quality. Like just about everything else that comes out of China, it is no good.

Anton, the link to pictures of your truck is a motorcycle website that requires membership.

First, have you cleaned every fuel line out, since you are turning it over, I presume none of the valves are stuck which often happens when burning antique fuel. Have you thoroughly cleaned the fuel tank, best to remove to clean even filling with rocks, tying it to a large tire and rolling around!

Those are normal procedures, if that is all done, then one can address the carb!

Ed

Thanks for the reply! The original carb is a Rochester model B, manual choke. Hence why I thought the Monojet, even if it's a clone, might be somewhat of an upgrade as it is a bit more modern in its construction.

As I said, I'm not expecting great quality from these things. From what I understand they can be hit and miss, sometimes you get a good one and sometimes you get a bad one. But for the price, maybe worth trying one and see if I get lucky? I dunno. The question is, will my original Rochester B outperform this chinese knockoff if I spend the same amount of money on it (plus the time rebuilding it) as the new one costs to buy?

Ah yes, I tried to insert an image link rather than upload directly to the forums since I didn't notice the option to attach files... Even still, I seem to have failed. Tried uploading a local file instead but I can't seem to isnert it into my post... Hope the new link works at least.

Anton,

I see you are on-line right now. I'm gonna re-title your thread here so it may draw more attention in Active Threads. I'm thinking readers may see "Amazon" and "eBay" and pass it by.

Will be back to help with posting an image.

Hi Ed, thanks for your input!

I'm using an auxillary tank with fresh gas fed by an electrical pump through an inline fuel filter, I've taken the original carb apart and cleaned it up, blew through all the internal channels and got everything moving freely again (almost everything that is supposed to move inside it had seized up) and I've also put a new ignition coil+leads on it as well as new sparkplugs. And I've made sure I have adequate compression and spark on all six cylinders. I feel like the carb has to be the culprit as everything else is in place, and the carb was in a pretty rough state when I got it off. I did clean it up thoroughly and got every internal moving component unstuck, and I have tested the functionality of the pump plunger and made sure everything is operational. It's giving fuel and the truck does start briefly, it just doesn't run properly or respond well to throttle movement, so I'm suspecting the carb is working somewhat but not well enough. Which is why I thought maybe the easiest step from here on out is get a replacement and see how the truck behaves with that. If nothing else it would serve as a diagnostic measure.

A,

Here's a series of posts with images to help you figure out how to post pictures.

Also, we have an IT Shortbus that have good activity to help you with posting pictures and other questions related to the site.

I appreciate the help, thank you! You may be right, I guess this is something of a "can of worms" topic... Again, no disrespect intended, hope it's not seen as blasphemous to raise the question. Just wamt to explore all my options is all.

One more post and you should no longer be moderated!

Thanks very much! I have tried following the step by step guide but I can't seem to get it to work... Once the file is uploaded I click on the picture in the attachment manager (the miniature thumbnail which says "Embed into post"), but all that does is insert the image link like this:
[img]https://www.stovebolt.com/ubbthread...umber/50446/filename/20221128_141830.JPG[/img]

The picture itself doesn't show up in the post, at least not for me... What am I missing?

Bushido -- Not blasphemous at all to ask questions. The only dumb/blasphemous question is the one not asked.

Still not sure what your problem is with the Rochester B. I've been running that carb on my 261 for years now -- works great. There are little things that should be addressed on a B that has sat awhile -- its not hard. The biggest problem I faced with mine was a pinhole in the float. Put a new float in it and no problem since. We have some excellent carb gurus here who can walk you through the usual suspects on your B. I would recommend chasing those down before throwing money at new carburetors.

Just a thought.

You have a brother Bolter in Sweden -- Karl. He's floating around the site somewhere ... He'd probably be a good resource for you, too. Maybe you guys could trade lutefisk recipes ...

Once you get a chance, it would be fun to give you the grand welcome in The Welcome Centre. That's the spot to tell us a little about you and your truck. With more pictures.

Another "fun" place is to plant your flag in the International Zone in the Side Lot area. See who else may be neighbors.

Obviously, most of your posts will be in The Shops area.

And ... maybe didn't notice, we have Stovebolt Volunteer Fire Department. Also, a bit of a "nitch" area (located under Big Bolts). We've got some energetic members of the SVFD.

Sent you a PM (for image problem). See the blinking envelope up near your name in the right hand upper corner.

Speaking from 60-something years of rebuilding carburetors, I've come to believe that very few people spend enough time cleaning a carburetor before reassembling it. A carburetor is really a pretty simple device- - -just a casting with a bunch of precision-drilled holes, so unless it's been on the business end of a sledgehammer, there's not a great deal to go wrong with it. The trick is to get those holes CLEAN! At one time, there were chemicals available that could soften the deposits, and high pressure air could then be used to dislodge them. Nor so these days! The environmental wackos have outlawed anything that has much of a chance of doing an effective job of cleaning a carburetor. Jon (Carb King), our resident carburetor guru has come up with an alternative- - - - -boiling water and dishwashing detergent. Dismantle the carb, boil the parts in a strong detergent solution for a while, and follow up with a rinse in clean boiling water. Then use a needle-point air nozzle and blow an outrageous volume of air through every hole to clear out the deposits the detergent softened up. Reassemble the carb and make all the assembly adjustments needed to put it back into as close as possible to "new" condition. The above process should put around 90% of the carbs you encounter back into acceptable running shape, certainly better than some offshore piece of junk. Good luck!
Jerry

Hi Anton,

Your carburetor probably has a lot of issues such as a malfunctioning accelerator pump, probably a warped body, and other issues common to the Rochester B.

Even so, I would properly rebuild the Rochester B with the best kit available before I purchased a knockoff from the slave labor factories in China.

I had two Chinese fuel pumps fail to work straight out of the box (well one lasted a few hundred miles) and am currently dealing with a substandard Chinese Carter knockoff on another vehicle.

Carbking will probably be by soon enough to give you some guidance.

Welcome to Stovebolt!

I would suggest first to detail what is happening; maybe some here could offer some testing tidbits to refute your thought that the carburetor is the culprit.

MANY ignition issues are diagnosed as carburetor issues.

As an example, if the plates in the distributor are "frozen" from non-use, and the distributor will not advance; the engine will not increase RPM, and may stall.

I would concur with all here who have suggested trying to troubleshoot your original carburetor first.

Just one thing to consider: Even if the Chinese knockoff is the finest carburetor ever made (it isn't!), what happens if you get a bad tank of gas and need to rebuild the carburetor? Pretty sure the folks that sold you the carburetor would be happy to sell you another carburetor, but not a kit!

I have had some sent to me for rebuilding, and even if I still rebuilt carbs; the machine work that would be necessary would be worth more than buying another DOZEN of the imitation carburetors.

As to parts for your original: the U.S. has sent 1000's of vehicles to NATO countries. Maybe look for a European vendor of military surplus parts.

Again, welcome!

Jon

Appreciate it John, thank you!

Honestly I don't know either. This isn't the first carb I've tried bringing back to life, I have followed the same procedure as I usually do of thoroughly disassembling, cleaning with solvents as well as elbow grease and high pressure air... Just can't get it to behave. And since I have eliminated basically every other starting issue that I can think of, I figure it has got to do with poor air/fule mixture supply... That's the main thing I can think of at least seeing as the engine fires but doesn't run well/for any extended period of time.

I started looking around for refurbished carbs, rebuilding kits and so on, and it was then that I realised the internet is full of these cheap chinese knockoffs with surprisingly positive reviews... I figured maybe there's something to them after all, if not every single comment and review is negative then maybe they are actually a decent budget alternative? It is not only about saving money of course, but my curiosity about these cheap carbs plays a part as well. are they simply too good (cheap) to be true, or do they actually work? I'm interested in finding out what's what, hence why I asked the question. Who knows, I might buy one just for the sake of trying it out and let you all know what I make of it. Either I come back with reassurance that these things are indeed utter crap, or we might be pleasantly surprised...

Thanks for the tip! Hope we run into each other then! Lutefisk is childs play, wait until we bring out the surströmming. That'll have you running in another direction for sure haha!

Thanks for the info Peggy, I'll be sure to do that! Still finding my bearings here so apologies if I jumped the gun and went straight to asking questions without proper introduction.

Oh. Certainly no problems. I'm the Admin person so I meddle in little way.

Thanks very much for your input! I certainly can't claim anything like 60 years experience, but I have brought a couple of carbs back from the dead successfully and I thought I got this one pretty well cleaned and put back together as well... Yet still it won't play nice. The boiling water trick I haven't tried, might have to give that one a go.

I'm not giving up on the original carb just yet, but I'm still interested in those chinese knockoffs. The online reviews actually do seem overall positive which is surprising to me as I too would have assumed they are utter garbage, and yet people seem to have them up and running on various models of cars straught out of the box. I mean... If all of them were [censored], surely that would reflect on the comments and reviews online? So How come an amazon carb seller kan get a +4 star rating on their products from several hundred independent buyers if the product isn't at least worth the money? I find it intriguing in and of itself, and even if I would manage to get my original carb up and running I am tempted to get one of these knockoffs an s see for myself what it's like. Might be surprisingly good, or expectedly crap. But one never knows without trying...

Appreciate your input Otto, thank you!

When I first got the carb off the truck it was completely seized, nothing worked, no moving parts were moving and no fuel was being delivered what so ever. After I cleaned it out I managed to get it to deliver fuel, the pump works, the power pistone moves freely, it doesn't flood or leak... In my mind it should be in working order, but it isn't. Well, something isn't at least... No idea why though.

Thank you very much Jon, and thank you so much for your input! I really appreciate it!

I will try my best to elaborate:

First of all, I am in no way doubting the fact that a properly functioning original carb would outperform any chinese copy every day of the week. That is a given. What I am pondering is simply, can I get my original carb back to functioning as well as a chinese copy for less money/labor than a chinese one costs. Will the performance of the chinese one be so bad that it doesn't even work, or will it work better than whatever the state my carb is currently in and can be after spending that money and work rebuilding it... It's mainly curiosity at this point.

Secondly, I have go the engine "running", but not well. For lack of a better word, it is extremely temperamental... I'm having to really work with both throttle and choke to try and maintain some kind of life from it, and she's sputtering and shooting from both the carb and the exhaust... I've had it running like this for long enough to work up a decent engine temp, and yet it still won't run properly. Hope this makes some form of sense, if not apologies for my poor explanation...

You raise a valid point about the longevity and maintenance of the copies, one I admit I had not considered.

I have tried sourcing parts locally to the best of my ability, and I'm not done looking. But for now, it's not looking good I'm afraid... I'll keep looking, and I will try to rebuild my original carb once more. But I'm still curious about how good or bad those cheap copies can be... As I said, might get one simply for the sake of testing it out. At the kind of money they can be had for, I don't really stand to lose much but might very well gain some interesting and useful knowledge in the process...

Thank you very much!

Based on your answers, I am not convinced you have a carburetor problem; but guess you won't know until you try something else.

Jon

I understand... Perhaps not, I am no expert. I just have a hard time seeing what else it could be... I have spark, compression and clean fresh fuel reaching the carb, and the carb is pumping fuel with each throttle move... I don't think it's a timing issue since the truck drove to where she was sitting and hasn't been tempered with since, so that shouldn't have changed... Any suggestions on what else I can try would be greatly appreciated as I keep suspecting the carb. What else could be a likely culprit?

Your condenser could be junk (even if brand new - most are). If you put a new one on, put the old one back on and see what happens. Make sure your vacuum advance is functioning.

Check for vacuum leaks around the carburetor and manifold and both ends of the windshield wiper vacuum hose by spraying choke cleaner around those areas while it's running. If the RPM changes, you have a leak in that spot. Use a bottle of propane gas to do the same thing.

Look down the throat of the carb while its idling and see if fuel is dribbling off the center venturi. Fl;oat level could be too high flooding the engine.

Thanks for the input!

Would a junk condenser still provide a nice clearly visible spark? I would've assumed I would find out if there was an issue with it while checking the ignition system over and I didn't see any signs of it going bad, spark seems strong and stable... And the engine does ignite and run for short periods, just not very stable...

I did try to check for vacuum leaks using some of cold start helper spray, it made no noticable difference as far as I could tell but it's hard to say since I can't get it to idle or maintain constant revs reliably...

I don't think it's a flooding issue, haven't seen any classics signs like wet sparkplugs or felt a strong smell of gas or anything... Looking down into the carb it produces a nice squirt of mist when opening the throttle, and I can hear it squirting when closing the choke...

Maybe I should try boiling the carb and blowing it clean once again, probably doesn't hurt anyways and it might dislodge some stubbord gunk that I have managed to miss.

Possibly. I had a new NGK condenser that gave up at about 1500 miles. Car started and ran sort of ok but rough. As soon as the pedal was pushed it started backfiring, coughing, sputtering, etc.I checked timing, timing chain slack, etc. thinking I had jumped a tooth on the flywheel or something because it couldn't possibly be the new ignition parts, could it?

Of course it was. More Chinese garbage.

I've since installed one of Jon Goodman's 200,000 hr condenser in every vehicle I own.

https://www.stovebolt.com/ubbthread...native-condenser-update.html#Post1388813

Check the wires going to the dizzy and check your points to make sure they aren't floating.

If you take your carburetor apart again, check the base and the main body for warpage at the mounting flanges on a sheet of glass.

Roger that, perhaps I thought myself done with the ignition system prematurely... Gonna have a second look at that and see if I missed something.

Thanks for the tip, I'll look into those for sure!

And thanks for the advice, will do!

One of the reasons I'm assuming this is carb trouble is because I've had similar symptoms before when I was working on an old cadillac 472. It behaved exactly like my Truck, it started but only kinda and wouldn't run properly or for extended periods of time, being extremely jittery with the choke and throttle. Then as now I thought I had checked everything else and decided that it had to be the carb. Did a quick swap for an old Edelbrock 1407 and a homemade adapter, it fired right up and ran as good as anything. I may be slightly stuck in the mindset "behaves the same, must be the same" so apologies if I come across as stubborn or narrow minded. If I had another suitable carb for the truck lying around I would simply try that, but I don't. Hence why I started glancing at those cheap chinese replicas...

Have you put a vacuum pump on the distributor vacuum diaphragm to confirm it's working?

Mike B

What is your fuel pump pressure at the carburetor?

The 216 should be 2-4 psi. I'm not sure what the specs are for the 261 but it's probably no more than 6 psi

Too high fuel pressure can cause the fuel bowl to overflow and flood the engine at all speeds.

You might also want to check the mechanical distributor advance mechanism?

If it has been sitting for a long time, grime and grunge may be causing them to stick and operate erratically (if at all).

Haven't tried that yet, will do and report back! Thanks!

Good question, I'm using a small electric pump but sadly is has no numbers on it... I doubt the pressure is too high though as you can hear it starting to struggle once the carb fills upp, and I haven't really seen any signs of flooding either.

Do you mean the movement of the distributor itself? It moves freely, easy to twist by hand so as long as the vacuum diaphragm is intact it should be working I think... Or is there another advance mechanism?

I have roots from your country.
That carburetor is not fun to deal with.

Look at this.
https://www.stovebolt.com/ubbthread...b-and-bc-work-revisited.html#Post1456274

It needs good intake vacuum, to keep the power piston held up and not allowing it to go over rich, as well as the power piston and feed to it not leaking, and also not plugging up the port at the bottom of the carb flange.

Hello! That's cool! Talar du Svenska?

Huge thanks for the link, I'll dig through that tomorrow (or later today, it's 4 in the morning over here) and see if I can find anything relating to my issues!

Yes, there is a mechanical spark advance that's separate from the vacuum system. It moves the rotor and point cam clockwise to fire the spark sooner according to engine speed, not load. You should be able to grab the rotor and turn it a few degrees clockwise against spring tension, and it will snap back to its original position when released. The parts of the centrifugal advance are located below the breaker plate where the points and condenser are mounted.
Jerry

Jag talar inte svenska, Just hope none of this is a bad word or something.
You will have to slowly train us all.

Thanks for the explanation! I can grab and rotate the distributor easily, and it springs back no problem once let go.