I'd like a little input on a problem with Clyde that has been buggin' me.

I bought the truck in '96 with 38,000 miles, all original and OE. Any modifications are noted in the signature. Over the last eleven years I've owned it only during one period of time did it perform like I really felt it should. That was after the second carb rebuild (MC/Holley 4180) in '03 when I added a quick change spring kit for the secondaries and went to a little lighter spring.

The first time I took it out after that rebuild it literally scared the hell out of me the way it took off! Running solo it was hard to imagine it was the same truck. Imediately after that we did a trip to Chicago thru the steeply rolling hills of western Wisconsin. When set on cruise the old girl actually accelerated up the hills after the vacuum dropped to ~5", it took a breath and bellered! it's way to the top! Both my wife and I looked at each other rather wide eyed and smiled. We ran the freeway like the trailer wasn't back there.

After that trip the performance deteriorated and even after the last rebuild in '05 it never ran quite the same. My carb guy, one of the best in the Twin City area I'm told, said I had just gotten used to the sound so I wasn't hearing it anymore. I have a hard time accepting that as the reason. I've driven trucks and operated machinery all my life and listen to what's going on. I'm not sure the '05 rebuild ever got a chance because on the first trip out I hadn't gone three miles when I was merging into freeway traffic on a hill, had just put my foot into it and the crappy NAPA fuel pump we had to install in Colorado to get home couldn't keep up with the carb demand, leaned it out and I got a tremendous backfire. It starts and idles well, no sooty tailpipe ... it just doesn't perform like a 460 should. The distributor was rebuilt and recurved after the second carb rebuild in '03.

We're starting to prep for our bi-annual trip from eastern Minnesota to southern Colorado coming up in late May. Since our last trip in July 2005 we upgraded from ~7900# 24' fifthwheel to a 26.5' that rolls down the road at ~10,000#. I felt that the elevation and long grade performance with the old trailer was acceptable but weak with any head or cross winds. In view of this last year I swapped the original set of open 3.54's for a set of limited slip 4.10's hoping for a big difference. To date I'm disappointed. I still keep thinking about the bellowing beast that I had and has disappeared on me. Throw that missing performance in with the 4.10's and I shouldn't have any problems. As it is now I'm a little concerned about making the trip.

My carb guy said the 600cfm 4180 is the perfect carb for my usage and technology wise not much has changed enough to justify buying a new one. He also related that if the secondaries weren't working my top speed would be limited, which it isn't, that my frequent rebuilds are due to todays gasolines and the fact that I only put on 3-5000 miles a year and the truck sits alot. I've installed a fuel pump shut off switch and run the carb dry before I store it any period of time. I don't drain the secondary bowl, just the primary.

As far as I can see I have a carb problem. It's now due for another rebuild (or a replacement) before the long trip and I'd like some other opinions on just what is going on here and what I should do. Some things I've thought of but don't have enough experience to answer:

Is there something my carb guy may be missing?

Am I getting a sludge buildup in the secondary bowl so the performance deteriorates?

Are the backfires damaging something that can be prevented. I understand there is an upgrade kit available for this carb.

The front tank has a new OE fuel pump and I detect no difference in performance between the two.

I maintain I should be hearing ... and feeling the secondaries.

Should I be looking for something other than the carb as a problem?

What the heck is going on here??

Any comments and suggestions are appreciated. What fun is a 460 that doesn't perform like the beast it is?

 

never drain a carb use gas stabelizer.stabil is good u will neverv get all the gas out of the card and it drys and then u turn the gas on and fill it with that crap

 

You should be hearing and feeling the secondaries, I can on mine. With a 4:10 gear it ought to pull like gangbusters, mine does with a 3:55. I tow a 30ft Wilderness 5th wheel, 8800lbs empty, 10100lbs loaded. I weighed to whole rig on a truck scale in Millersville MD at 16120lbs. a number of years ago. Check the secondaries with the engine off, open the throttle fully, then move the secondary throttle shaft to open, make sure it isn't sticking and returns to closed. Check your timing chain for slop, take the distributor cap off, turn the engine until the rotor moves, then go back until it moves the other way. If there is an appricaiable amount of slack, then you are getting more than the normal 4 degrees retard on your cam.

 

I had the same problem after installing a rebuilt carb. on my 1986 F350 with 460. I couldn't hear the secondaries open and, after much agonizing, discovered that the carb. base gasket didn't exactly match the carb. The secondary butterflys would hit the edge of the gasket just as they were beginning to open.

You might try operating the secondaries manually with the engine off and look down the throat of the carb to make sure they are actually opening.
Jim P.

 

It's not a matter of stale fuel, I use Sea Foam for over winter storage, it's fuel evaporation.

The problem I was having was that after not being driven for a few weeks (only 3-5,000 miles a year and that's usually trips) the carb would dry out and leave varnish in the bowl, generally gumming up everything. It was my carb guy that suggested this. He has one customer with a situation like mine that drilled and tapped drain plugs into the bowls. An alternative suggestion was to crack the bowl retainer screws enough to let the gas leak out and then retighten them. I didn't want to drain gas on the manifold so I chose to try the "run dry" option. I have since the last rebuild in '05. If I do another rebuild on this carb I'll have him "autopsy it" to see if gummy residue is still a problem.

I've got to say I hadn't considered the possibility of a clearance problem. In my researching I remember reading that there was a gasket mismatch problem in some Holley applications. Will have to check this out! Thanks for suggesting this guys. It sounds like it may be a common problem.

 

Well, I checked for restrictions as both Bill & Jim suggested and after removing the spring from the vacuum chamber, holding the throttle wide open and moving the secondary plates there was no binding. I did notice a little resistance about half way before I removed the spring, but I'm thinking that's just the diaphram and if it were operating on vacuum it should be ok ..... ???

As I was fooling around with this I decided to get something done that I've wanted for a long time. An indicator that will show when the secondaries start opening and with any luck I can get it to show me when they're wide open too. That will tell me A LOT about what's going on under the hood that you can't see in operation.

If this indicator setup works it should help me keep my foot out, operate at an economical speed. Hopefully even get a chance to "test fire" it today.

 

A bad power valve can cause serious problems. You can check the power valve without removing the carburetor from the engine, just remove the front (primary) float bowl and unscrew the power valve. Apply oral suction to the threaded end of the valve; if you get flow then the valve diaphram is ruptured (usually due to a backfire through the carburetor). Different 4180C carburetors for different vehicles use different 2-stage power valves
that operate at various vacuum levels. My '83 (10,000 GVWR) with 460, C6 and 4.10 uses carb E3TE-9510-RC List # 50003. The power valve is Holley # 125-216 (Walker # 70-29). The first stage operates at 8" Hg. and the second stage at 1.5" Hg. Yours is likely close to that.

 

I think I'll put that on my "list of things to do tomorrow" Ken. I'm getting pretty disgusted with this carb business. Rebuilt in '97, '03 and again in '05. If I do it again and add the blowout protection kit it will darn near equal a new 4160. Mine is an E3TE-9510-RD List 50003-1 4180. A likely progression from RC (83) to RD (84), eh?

I mounted a micro switch to show when the carb starts to open (still have to work on the full open indicator), but it doesn't even look like the secondarys are opening. Hard to tell without a load. Thinking about putting a lighter spring tomorrow and see if that makes a difference. Maybe I have a diaphram problem ... Has this been a problem for anyone??? Blocked port or passages ???

For what it costs to professionally rebuild one of these things I'm giving serious thought to just picking up a new Holley 4160, Truck Avenger or maybe step off the Holley dock entirely and try something else.

I did a Carter AFB many! years ago and swore off four barrels. What does it cost for kits and such on a "do it yourself" basis? Middle of May is fast a comin' and I have to be "bullet proof dependable" by then.

I appreciate any input .... keep it comin' guys! Maybe we can all learn something ...

 

Draining the fuel is good in theory, but you still have the problem of the gaskets and diaphrams drying out, shrinking, and getting hard. The best you can do is keep stabil in the fuel, and go out and start it up every couple of weeks and let it run till it warms up.

Something simple to check is get someone to hold the pedal to the floor inside the cab, and you check to make sure the carb is wide open. Sometimes things happen like new carpet, etc. that can change things.

Also remember your carb has vacuum secondaries. If the engine is pulling hard at a fairly low rpm, the secondaries will not open. They operate on the air rushing down the throat of the carb, so they will not open till the rpms climb enough, and the engine can actually use the extra air and fuel supplied by the secondaries. So you may want to check and make sure the c6 is kicking down like it should be.

By the way, you may be able to hear the secondaries kick in, but if you "feel" them kicking in, what you are feeling is the engine bogging a little bit because they are opening a little too quickly.

P.S. If you want to play around a little bit, remember I didn't tell you this but, if you look on the driver's side of the carb, you should see a half-moon slotted piece on the secondaries, and a linkage rod running from this slot up to the primary lever arm. This little setup is to force the secondaries shut when you let up on the gas pedal. What some people do(which is a big no-no but oh well) is take a small screw and nut and bolt them through the slot next to the linkage. If you do this, it forces the secondaries open. I am suggesting this only if you want to experiment temporarily. If you leave it like this, and feed the engine carefully, it will work, but if you slam the throttle open, you may get a backfire up through the carb.

 

A lot of good thoughts. I didn't see where a blow out protection device was installed with all the rebuilds. Without it any backfire will blow out the POWER VALVE. On the 4180 they didn't come from the factory with one. I use a Centrex type. They are very easy to install no drilling. Just unscrew the front screw on the bottom of the carb and screw in the Centrex device. You can buy online from centrex.com
Just a thought.

I only drive my 86 F250 4x4 460 about the same mileage as you. I try to start and run it every week a few miles just to keep the gas from sitting to long.

 

Put a paper clip on the rod that activates the secondary throttle butterflies. Put it up against the bottom of the secondary vacuum diaphram operating assembly so you can tell how far the rod moves and thus how much the butterflies opened. It may take a little experimentation to get the right shape/tension of the paper clip. I used needle nose pliers to bend a slight "U" in one side of the paper clip. Took me about three or four tries to get one to stay on the rod and hold its position. This is a good indicator of how the secondaries operate under load. I only use Holley or Walker carburetor kits/parts. Over the years I've had too many problems with others. I think a 4180 kit would be about $45-55. Age/heat cause diaphrams to go bad. OBTW, I am not the originator of the paperclip idea, I think I first read about it in an old manual about 30 odd years ago. Since I usually can't find carburetor parts like I want around here I order from http://www.swapsupply.biz/ .

 

A kit for a 4180 is around $100. I have accounts with both NAPA & CARQUEST my cost 3 years ago was $91. I went to a 4160 after the first rebuild. By buying a new Holley 4160 600 CFM for $234 I didn't have to worry about POWER VALVES. After 1992 Holley installed BLOWOUT PROTECTION on all of their carbs. The 4180 has a 2 stage power valve and they aren't cheap either $30 each.
After reading this post I had to go out and start my ole F250 and let it run awhile. I'm getting close to the day we will pull our travel trailer to Southern Nevada. It's a 450 mile trip. We live in our RV full-time. The ole F250 is ready to go to work.

 

Looks like SouthWest Auto Parts gets $74.81 (plus shipping) for a Walker #15893C repair kit for a 4180C but I'd verify before ordering. What makes me really wonder is why so many rebuilds are necessary. I've never had to rebuild a carb with less than 75k miles except my current 4180C which had been butchered by the previous owner. It had suffered such indignities as stripped fuel inlet threads, drilled out main jets, wrong power valve, broken choke housing, etc.

 

You have been lucky. I have talked to other people too, and it is a general consensus it's the fuel today.

I have quite a few old cars sitting around, and always have carb problems after they sit. Lawnmowers, snowblowers, chainsaws and weedeaters don't seem to be exempt either.

I believe if this was my truck/rv, I would also have to consider a new aftermarket carb, especially for the price. But before I did this, I would have to lift the hood and do a survey of all the hoses and stuff, and have a plan for each one, since the new carb won't have as many connections.

 

I've spent the last couple days doing a lot of researching. The input and knowlege I've gotten from this forum is, as usual, highly valued. It's like being able to go down to the local watering hole and tell your problems to a bunch of friends that share the same problems. Thanks again guys!

I went out to the "barn" today with the full intention of tackling this problem. Before I sent the wife off on her quilting excursion I had her help me verify colors on the set of secondary springs I have (little color vision thing going here) with the plan to stick in the long yellow after checking the power valve. Never did get the power valve out but managed to "booger up" the fuel tube to the back bowl and now I've got a leak So much for any further testing. I shut off the lights and went to the Men's Mall (Fleet Farm, Menards and Home Depot) looking for consolation and some away/thinking time. I also had a couple beers when I got home before I composed this .... wish a few of you could have joined me

In summation, all things considered, etc.:

So far the three rebuilds, necessitated over the years by blown power valves, accumulating varnish from evaporation during storage, crappy gas, and no doubt a little of my own stupidity somewhere along the line, have some to a grand total of $586.28. Fact.

The multiple sites I've visited (Binder Bulletin, the IH people, has a real character who seems to know more than a little about carbs) have led me to the conclusion that the 4180 is a "ragged edge" emissions transition carb without a whole lot of self redeeming virtue that would make it stand out in a crowd ... and mine is in need of help. Opinion.

If I'm going to rebuild this 4180 again it is definitely going to get the power valve protection upgrade that my carb guy talked me out of last time (?????). That combined with the regular rebuild is going to push me over the price of a Holley reman (65-80457) http://www.nationalcarburetors.com/h...px#bookmark2or
or even a new (0-80475) 4160 http://gatorperformance.com/product....4&bestseller=Y.
What am I doing even considering another rebuild of this thing? Conclusion.

I don't have to work until afternoon tomorrow so I'm going to take a swing over to see my carb guy in the morning. If he can even come close on price I'm going to have him order one in for me. I like to support local business whenever possible so they can be there when I need them for service and questions. If he's too far out of the ballpark ... I tried. I'm swapping over my quick-change secondary kit.

I've also looked at the 670 cfm Street Avenger but is it really worth a couple hundred bucks more ???? Question.

Now to figure out how to keep a new carb from gummin' up inside. Stabil has been mentioned a couple times. Will that stop evaporation or simply keep the fuel from going bad? Personally I'm a Sea Foam fan but I don't dump in a can a tank every time I refill them. Most of you guys have an advantage on me that you can run your trucks year around. Clyde sits from November thru March usually ... ugly white stuff out on those winter roads up here.

I know I didn't hear about the "cheater screw" from anybody here of course, but I tried it on my last trip before the '05 rebuild and it made no difference. I'm thinking it's because the secondary jets are actually gummin' shut due to evaporation varnish. Possible ???

I worked as an ag engineer for a seed company buying and maintaining a lot of big block Fords and Chevys in the late 70's and 80's before FI. I just don't remember rebuilding more than one carb and IIRC that was well over 100K when we did it. The 460's were my favorites (can you tell?), we had some runners and we had some dogs but for the most part they did a hell of a job pulling 3600# trailers with as much as 13,700# combines ... weight and wind resistance. All OE. That's all I want, a good dependable pull.

Re: Frequent Rebuilds
According to my carb guy, and a few others I've read, it's not at all unusual nowdays to have to rebuild every two-three years due to storage, varnish, cruddy gas, drying gaskets, chemical reactions .... a whole bunch of reasons. Back when I was herding a bunch of carb'd big blocks we used them every day and had good cheap fuel to feed them. No problems.

One guy I read was depressing. He said carbs were obsolete, parts for all but the popular ones were disappearing and there was little reason to innovate materials just to deal with collectors problems like I mentioned above. I sure hope it's better than that!

Still looking to learn things and certainly appreciate any help I can get to keep old Clyde productive and happy. Dialog is good!

Now I hope this new carb does the trick!!!