Holley Carb Blues

[TollyWally]

Last year the powers that be mandated additional ethonal in the gasoline sold in my fair state. This was the start of many related troubles. I went through at least 5 sets of filters last summer and thought I had the problem well in hand. I have a stock BBC with a spreadbore Holley 4100.

In the fall I went out and barely made it back in. I have already installed a dual filter system where I can switch from one filter to another while running. The fuel goes from these in line filters to the stock fuel/water seperator and finally to fine screens at the fuel bowl inlet.

When I got back I thought the needle valves that control fuel into the bowl were clogged. I pulled those and then stripped the threads adjusting them.
Sadly I was suddenly struck with some rather serious medical issues and couldn't get back to my boat for over 6 months. Yesterday I reassembled the carb and fooled with the float adjustment finally getting it so fuel wouldn't flow out of the level plugs on the side of the carb.

I ran it for 20 or 30 minutes at the dock yesterday and things seemed fine. Today I ran it for 20 minutes at the dock and then took it out for a run. I left the hatch cover and aircleaner off to I could keep an eye on the carb , check for leaks etc. After leaving the harbor I took it for about a 3 mile run at various speeds. It seemed to run pretty good but needed a little tuning of the air mixture screws according to my vacuum guage.

I came back into the Harbor and rafted up to enjoy a big annual Party for the fishboats heading north. Heading back to my dock after 4 or 5 hours rafted up it started fine and then died 150 yards from the raft. It was very hard to start, I got it to fire with ether and barely made it back to the dock.

Tied to the dock I investigated and found that gas was just pouring down the secondaries at idle. I'm wondering if my original problem 6 months ago was flooding instead of clogging. In any event I am a little puzzled as to what to do next. Money is a little tight after my illness otherwise I'd probably just have my carb rebuilt. I've never rebuilt a carb before, all though I am sort of willing to try.

So in summery I have
a tank crud problem
A carb problem
not quite as much money as normal to throw at this.

Suggestions and advice would be appreciated.

[CDK]

The most likely culprit is of course the float itself or the tiny valve that should perfectly close when the fuel level is reached.
If you have never dismantled the carb before, you need a good exploded view drawing to put it back together again. If needed, I can copy some pages from a book about overhauling carbs and post them here.

[Manie B]

I dont know the Holley 4100 - but i work on small carburettors every day of my life, i run a small tools plant hire business.

I would think that a "carb kit" in your country should be cheap and hopefully easily obtainable.

The biggest problems that i find is the fuel mixtures of today leaves a bit of residue, almost like a white powdery slimey film that clogges up the main jets.
We remove float bowls very often to clean out and also find many faulty float - needle and seat problems.

To me it sounds like you have a needle and seat problem which should be replaced and any internal "screens" that also block
The old Tillotson carbs are notorious for internal screens

I find that most any carb will run well if the above is ok
with us a badly worn carb is not a problem - it simply wont alow the engine to idle well, but when the trottle valve opens the engine runs perfectly on its main jets. A worn carb is still easy to start as we start our engines with the throttle half open anyway

hopefully this will shed a little light

[TollyWally]

Thanks for the input everyone.

CDK, I have a good exploded drawing but any information you might post will be appreciated.

Manie B, I replaced both needle valve assemblies but I will be checking everything out again. I imagine a career such as yours makes you pretty valuable in a mechanical pinch. Thank you indeed for shedding a little light. I love your signature

[thudpucker]

Tolly if you think the back float might have been the original problem, did you take a close look at the float to see if you dont have a pin hole(If its a Copper air filled chamber) or if its the Cork float, sometimes the clamp comes loose from the cork and the float will jamb up high holding the Needle open.

IE; I think you might have a mechanical problem with that back float.

Manie, have you come up with a Chemical that will clean that White gooey stuff out?
We have that with all kinds machinery all over the contry and nobody has mentioned any additive or wash for it yet.

[Manie B]

Manie, have you come up with a Chemical that will clean that White gooey stuff out?


What i have found to work for me is to strip the carb down and soak it overnight in petrol (gasoline) then brush very clean with paint brush, and blow out with compressed air.

Lately 90% of my problems are carburettor.
The problem is with the down turn of the economy rentals are low, i try to rotate my machines when and where i can, but it is not always possible. So i end up with machines standing for months and not going out to customers. I now make sure that when a machine comes back in, we run it until the carb is dry and then empty the fuel tank out. When the carb is left standing dry and empty there is definately less problems next time you fill up and start. Our sh1t fuel goes cloudy in the tank, if left standing for a couple of months. I am not sure why but it seems like the alcohol and fuel seperate - FACT IS the engine is a bitch to start with old fuel and runs badly.

I would suggest to boat owners (two OR four stroke engines) to install a fuel shut off valve on the fuel tank and to run the engine until dry. I feel that a "winterizing" approach is always better if a boat is going to stand long. Then keep fuel in 5 litre (one gallon) tanks so that you dont have too much fuel in your built in tanks. Extra fuel goes to your car anyway.










jeez when is this ecomony gonna pick up:(

anybody want to hire compaction machines :D

[mydauphin]

I have a construction business with multiple equipments of all types and the fuel quality is terrible. Two or three times my diesel trucks have had to get their fuel systems purge. Chainsaw have problem starting and gas won't perform properly. Between the water, ethanol, dirt, fuel supplier adding whatever to extend fuels. All my mechanic friends are making a fortune.

So some ideas to lessen problems.
Don't buy from the cheapest supplier. Buy Name brand.
Use something like Baja filter to filter going into tank
Install water separator,
Install another filter
Install visual filter on return line
Replace hoses if necessary to make it Ethanol compatible
Don't let fuel sit
Use smaller multiple tanks instead of one big tank
Running engine dry as stated above, though not recommended before might be a good idea.
If I am not going to run engine for a while I pour wd40 into carb , float area and cylinders.

I am sure there are others, but these come to mind

[Frosty]

Your making this hard for yourself.--Google holly carbs, there is more information on those than you could ever want.

[Jimbo1490]

Sounds like it may be one or more power enrichment valves stuck open. After you left the dock, you no doubt opened the throttles to get up on plane. This induces a sharp increase in manifold pressure which triggers the power valves to open. In normal operation these should only open briefly. If they are faulty, (if the have dried out hardened diaphragms, for instance) they may close too slowly or not at all, flooding the engine out. The power valves are located on the primary side metering block, which is between the primary side float bowl ass'y and the throttle body.

Jimbo

[PAR]

Some of this may be related to which carb you have, but most is probably ethanol related.

Ethanol has created a whole new set of problems. The rubbers, some gasket materials and coatings are being effected by this stuff. Coatings are being stripped, rubbers, plastics and gaskets melt, etc.

The first thing you should do is replace the fuel lines with ethanol suitable lines, then a rebuild kit for the carb. Rebuild the carb, including the diaphragms in pumps or power valve seals.

With close inspection you'll see little balls of rubber, plastic and gasket material, in the obvious collection areas, within the carb.

This is the carb, I'm assuming you have.

http://www.holley.com/data/products/pictures/large0-80552.jpg

It's the 650 CFM electric choke, vacuum secondary (universal application, replacement for the Quadra-Jet). If yours looks different, provide the model number (usually stamped on the primary air horn).

[Frosty]

You see the slider on the vacuum secondaries, you can but a small nut and bolt in there and make it into mechanical secondaries!!!!!!

[Jimbo1490]

You see the slider on the vacuum secondaries, you can but a small nut and bolt in there and make it into mechanical secondaries!!!!!!

Not a good practice without doing either or both of the following:


Substituting different (higher flow) power enrichment valves

Changing the secondary float bowl assembly to one that includes a second accelerator pump.



Otherwise, you will get a very bad 'lean bog' when you open the throttles.

Holley makes plenty of mechanical secondary carburetors, but they always (AFAIK) have dual accelerator pumps, dual metering blocks and power enrichment valves on both primary and secondary sides.

Jimbo

[PAR]

Damn, you beat me to it Jimbo . . .

[Jimbo1490]

Been round the block a few times with Holleys from little 2300's all the way to 850's and Dominators.

And they do like to leak. :D

Jimbo

[PAR]

Leaking has always been a problem. Hell, an 850 Dominator is a leak. A slow garden hose flow of fuel, into the intake. You can physically watch you gas gauge neddle move . . .

The optional accessory metering blocks can help. Use a Demon and skip the fuss . . .

[TollyWally]

I appreciate the input gentlemen,
With any luck I'll get to the boat Sat. Morning. I'm ready for a test run but I need a buddy to run along side me in case things go bad.
I've adjusted the float level and checked the seconday power valve gasket.

Par,
That is not my carb. Mine is a holley 4100, a spreadbore patterned after the Rochester. It does not have the detachable float bowls like the one you have a picture of. The top of the carb comes off and both float bowls are revealed.

Again I appreciate the input and will be seeing what there is to see Sat. morning.

Carbs seem to be my special nemisis right now. I am helping a guy who keeps his boat at the same dock with his carb problem too.

[Jimbo1490]

That sounds like a 4100 Motorcraft/Autolite (http://www.carburetor.ca/carbs/HTML/gallery/Ford/4100/Ford4100-1965.jpg), NOT a 4100 Holley. That's actually a better carb than the 4100 series Holley. Does it look like the one I linked?

Darn confusing that they have a similar model number, huh?

Jimbo

[TollyWally]

Jimbo.
This baby is a holley. It is the stock carb on a mid 90 Volvo marinized BBC crate motor. The top comes off like your picture but it has the needle valve adjustments for the float level on the top at each end. The fuel comes into the float bowel high. Choke and vacuum advance for secondaries is a little different. Despite my best intentions I didn't make it Saturday. Hoping for tomorrow.

[PAR]

It sounds like the Holly casting of the Quadra-Jet (they bought Rochester), which I don't have an image of, but know the carb.

[TollyWally]

Interesting Par,
I knew that it was patterned off of the Quadrajet but I didn't have any idea Holley had bought them out. Somewhere In my research travels I've seen mentioned that the base bolt pattern or whatever? matches the Quadrajet flange pattern. I don't know much about Rochesters (or any other carb for that matter :) ) but most of the other features like the fuel line location, float level adjustments, float level sight screws look like pure Holley to me. But who knows. I learn a little something from each guys input, thanks fellas. I'm headed for the boat in about 2 hours, hoping for a little luck.

[PAR]

http://image.chevyhiperformance.com/f/8869695+w750+st0/p114965_image_large.jpg

Two Rochester carbs, both automotive, but similar, except for marine upgrades. Electric choke on the left, well tube, mechanical on the right.

It's an easy carb to work on, tune and rebuild.

[thudpucker]

Good photos. I had three GMs with Q-jets and liked them.
My work partner had a 65 SS that burst into flames out on the freeway. The FD said it was the Q-jet. Must have been one with those flimsy rubber diaphrams.

[TollyWally]

Thanks for the photos Par,
My Holley doesn't look much like those carbs except for the spreadbore similarities.

I pulled the top yesterday and double checked the float hinges etc. The fuel in the bowl looked suspicious. I'm beside myself with irritation over that fuel, I have less than a half hour on the multiple filters in the system. I tore the gasket on the top too. It is new but I have had the top off several times. She started fine and idled ok for about 15 minutes. Today I am going to mount a kicker motor, if that works out I'll test her under load and be able to make my way home if things run amuck. Again thanks for the input and wish me luck boys!

[Jimbo1490]

TollyWally,

I don't recall ever seeing a Holley carb that had a float cover as you describe rather than float bowls mounted on the ends. Holley has purchased several carburetor manufacturers over the years, so this may be another manufacturer's carburetor wearing a Holley badge.

PAR,

You have a 4M and a 4ME there. The last several I've rebuilt were the newer M4ME with the APT metering circuit. Those Rochesters were near the pinnacle of carburetor development. This is partially why GM switched to EFI so late; they did not need to make the switch because their carbs, unlike many others, actually worked well and met the newer emissions standards. They are much easier and less tedious to tune to a given engine than the Holleys becuase you don't have to keep changing jets, just move/change the metering rods.

The carbs on the 80's Hondas were notorious for their overcomplexity and ease of going out of whack so that the car would fail a smog test, despite the engine being sub 2 liters displacement.

Jimbo

[TollyWally]

Well got the kicker mount installed and the kicker in place. Tomorrow fresh fuel for the kicker, if she runs then out for a test on the big boat motor under load. I'll try to upload a pic of my carb.

[El Sea]

TollyWally,

Sounds like ethanol.
We clean fuel tanks daily and currently every boat that we have serviced has had what I refer to as being 'ERI', Ethanol Related Incident. Pumping out the old fuel and replacing with new will not cure the issues. You need to remove all of the sediment from the tank and treat the fuel before the phase separation takes place and before the ethanol attacks your fuel system components. Ethanol love to destroy rubber, plastic, o-rings and pumps.

Luther Carrier
www.absolutetankcleaning.com

[PAR]

I'm seeing the same thing and suggested so in an earlier post. I'm getting a fair amount of work from ethanol.