Holley Carb questions and answers

[Michael C Henry]

I thought that I would bring all my burning questions concerning holley carbs and everything connected to one location. you guys have supplied answers and sources to many subjects like who does what, has or has done what, tools ,parts etc.I've learned a lot recently ,stuff I should have learned thirty years ago.
My situation while not unique is not common. I'm running inline dual fours, Holley1850's.They are a fit everything, short, and cheap carbrueter. I have them on a Dove tunnel wedge 2x4 intake manifold.It has open flange rather than four small holes for each carb. The standard practice is to leave the center three base screws out because they may fall into the engine, I can see that now.I didn't know this before.
The 1850 has vacuum channels underneith that arn't used and are outside the manifold mounting flanges. They make a plate to go between the carb and manifold with another gasket.I'm allready height chalanged and I do not need to rais the carb another 1/8". So I had the unused channels filled with epoxy.This operation was originaly done for me by Guessford Machine.
I milled off the choke towers my self because there was no butterflys in the carb anyway. I had several fires and backfires so the carbs weren't pretty. I had these old carbs gone through and redone .I ,at first couldn,'t beleive that they were the same carbs. after some examination I found some potential problems.
The current problem is that the white plastic float bowl vent baffel (whistles) had been removed. I have these on a big FE in a small car and I drive like you'd expect.I'm sure the fuel is sloshing all over the place. I've been told that the whistles are not to be used with the side hung floats. besause they may stop the float from closing the needle and seat, I have Nitrphyl floats . the secondary floats were altered By Quick fuel Technology for their metering plate kit to clear the replacable jets. The secondary float was altered and sealed with what looks like Epoxy. I plan on trying to alter the floats in the primaries by notching the tops to clear the whistles. I have now read that the nitrophyl floats absorbe gasoline over time and quit floating ( Car Craft Jan 05 pp37) . One question is the surface finsh on the black nitrophyl critical to keeping the gasoline out? Is ther a new better float material? Is ther a special epoxy?Any thoughts, remedies, sources , etc.?
Please add your questions concerning Holley's to this thead so I (and others) can absorbe the answers.You guys have helped a bunch.

[Michael C Henry]

What are the differences with duracon floats?

[Ron61]

Michael,

Rick Parker uses the whistles in his single Holly, and I believe he told me that he just trimmed a little off the end of the whistle to clear his floats. He has done a lot of work on the Holly and you might contact him as he really knows what he is doing.

Ron

[Michael C Henry]

What I was told they may keep the side hung floats from closing the needle and seat. the float would stop at the whistle and not rise to close the needle and seat . I read in Car Craft that the nitrophyl floats may absorbe gasoline causing them to sink. I'd think that someone would have addressed this before. I do not know over how long a period they were talking about.i don'tnow if they have improved nitrophyl since.

[Big-Foot]

If you do this "BEFORE" you expose the floats to fuel, it will work;

Carve out the section of the float that interferes with the whistle by using a dremel tool. Now, mix up a batch of the good (takes 8 hours to cure) JB Weld - don't use the 1 hour stuff - and carefully paint over the area you just carved out and have a little over the edge to "seal" the float. It will work. Nitrofill floats are impervious to just plain gasoline, but Octane Boosters are another matter.
Frankly - I would just trim the whistles a little and connect the two bowl vent tubes at the top with a short length of rubber tubing and put the vent holes in the top of the tubing. Well - That's my $.02 worth anways..

[Michael C Henry]

I finaly found the JB weld that takes forever to set up.at Loews.The floats didn't come ,backordered . The ProForm float adjusting tool came ,it is beautiful.
I found out the Duracon floats are the hollow plastic they become pink after use.. There seems to be a nation wide shortage of Holley Nitrophyl side hung floats. Jegg's said at least 15 of Dec .That is another two weeks.

[Michael C Henry]

The Nitrophyl floats are easy to notch.As I heard the Nitophyl material is impervious to gasoline.Then why the epoxy? Is the surface finish that came on the floats originally a barrier or is it the actual material it's self ? If the material is prone to saturation by octane boosters then a paint on coating sounds like a fix.Know of any?
The vant baffles that I ordered from Jeg's (26-40) were the longer 2" ones were a little short for my regular bowls I have.Trimming their length being too long was not an issue .The shorter baffles/whistles are # 26-89 and are 1 7/16" long . They angle down after leaving the rectangular socket .I tried the upward position and there is severe interferance with the top of the bowl even before full engagement. The slot in the top of the float needs to be deeper oposite the hinge and rear . As if the float would reach the roof of the bowl and never tooch the baffel .
The new Avenger carbs have a metal vent tube that connects the bowls and is vented with holes drilled in the top as it jogs side ways to miss the aircleaner studd and low enough to fit under the aircleaner.. I have the cast vents that are tapered and the primary taller than the secondary.

[Big-Foot]

Mike - The floats are supposed to be able to maintain their buoyancy (sp?) even if the surface is damaged. However, I have run into two of them now that were half sunk because they weighed more (hint - the only way they can weigh more is if they are laden with fuel). Upon examination with a magnifying glass, I found one of them had a small darker spot on the bottom and further magnification showed that the float had been contacting the bottom of the bowl and had rubbed a small bit of the surface away. The Droop tab had been mis-adjusted. The other one had a small nick in the side. This is why I recommend re-sealing any damage or modifications to the float.

Vent Riser Tubes - you can buy a short length of steel, aluminum or brass tubing from a hobby supply store and either swedge or epoxy the riser tube in place.

[Michael C Henry]

The epoxy is realativly thick .Is there a thinner coating that could be painted or sprayed on?
Now looking for a tubing bender that will make a fairly tight bend in a 5/16" tubing.
The tools from Willies came . The float tools were almost the same .The bodys looked the same except the checkering was different and and Willies had the hex socket points were radioused. The knobs were made differently . The ProForm inner screw part has a hex head on the steel shaft that the plastic knob is atrtached to .The Willies tool the shaft has a knurled end that the knob is pressed into. But on the table they look almost the same.The power valve tool worked as advertized.

[Big-Foot]

Hi Mike, The JB Weld will look pretty thick, but it flows out as it cures. I would probably paint it on using a flat toothpick and juct carefully control the amount you put on. If in doubt, try mixing some up and test it on something else. It's good tough stuff and I know of absolutely no other epoxy that is as strong and fuel proof like that stuff..
It could be called Liquid Duct Tape - it is that good!

[Michael C Henry]

Do you realy blame a small rub area for fuel saturation? I tried to klean up the runs and such,but if it is that critical maybe just paint the whole thing with epoxy?
I've got one of the vent tubes promoted. I cut off th cast vents. The tall one is now the same heigth as the short one.Drilled the cast vent stacks and installed short pieces of SS 5/16" tubing. The crossover tube is connected by short pieces of blue silicon hose.That way it is removable .It all has to fit under the Stelling ang Helling air cleaners.and the squirter is accessable.

[Big-Foot]

Originally posted by Michael C Henry


Do you realy blame a small rub area for fuel saturation?

What would you conclude from the following;
* Float weighed something like 5 or 6 grams more than a new one of the same mfgr.
* No flaws in the float except for the mark on the bottom where it had been rubbing/banging the bottom of the float bowel
* under magnification, you could see the open cells of the foam in the rub area.

I tried to klean up the runs and such,but if it is that critical maybe just paint the whole thing with epoxy?

I suppose you could do that, but you would also add considerable weight to the float in the process. If you are careful with the JB Weld epoxy, you will add negligible weight to the float.

Quite honestly - I think that you would have the matter well in hand with just using the little brass baffles and the vent tube extensions and silicone tubing.

[Michael C Henry]

If the float is sealed by the surface coating why cann't we recoat it with the same stuff?Some kind of spray or dip. As I remember it someone said it isn't so much the gasoline that penatrates as the octane boosters. and I have no idea of how log a time we are talking about.
I got the 5/16" SS tubing all cut and bent . I cut the cast vent stacks down .ended up drilling with (O) drill bit . fits snug . Last hole the bit caught picked up the carb body and bent the bit. I tried to straighten and it broke. I'm now looking to buy a new (O) bit Monday . I decieded to go with a one peice tube bent out to clear the accelerater squirter access. Then the Craftsman moto tool gave up and I had to buy a cheapy tubing bender from Harbor Freight. The second bend to kit it around the squirter close to thfirst bend downward was the hardest.

[Big-Foot]

Sounds like you have had your hands full with this project Mike.

As far as sealing the floats with something else - I guess it would be a trial and error process, but whatever you chose, it has to be able to put up with being immersed in fuel for months on end..

Octane boosters are bad for anything that isn't metal. Most of them used some form of Acetone or close chemical compound. If you ever need some glue to hold two pieces of plastic together, just use a dab of acetone between the two pieces - Instant weld..

[Michael C Henry]

In the book "holley Tech" pp14 lower left corner .They show Don Kelly of Braswell carbrueters, spreading epoxy on a float with a can of LocTite #445 in the picture. What is that about?

[Big-Foot]

445 is a fast curing epoxy. I think I would probably spread a little on a scrap of aluminum foil, let it cure and put it in a glass jar with some fuel in it for a few weeks to see if it softens or disolves.
You may want to contact Braswell to see what they have to say about it.
Loctite makes some fine products - not a doubt in the world - however, I have used JB weld in high temp and fuel contact situations without any issues at all for many years. JB Weld costs a few bucks, I am sure that the Loctite would be substantially more expensive.

[Michael C Henry]

I installed the carbs and roughly adjusted the float levels. Started the engine in my little garage. I'll have to wait till the weather clears some to get it outside and rum it at length.
With the carbs tipped down at the front primaries high to the rear. Should I set the float level in primaries low at the site screw?

[Big-Foot]

Hi Mike,

Set your float levels at a warm idle and have the fuel barely at the bottom of the site screw hole. Matter of fact, I set it so I have to rock the engine slightly to get fuel to slosh out of the hole.

[Michael C Henry]

The rocking the engine is my usual way.It is hard to see the actual fuel level unlees it is running out.I want the outside dry and fuel to appear when the car is bumped. With the carbs tipped like they are the rear primaries it should take a bigger bump so fuel isn't so high against the metering block.The actual engine is almost level front to back but the manifold carbrueter mounting plane is higher in the rear so the carbs are tipped down at the front( secondaries forward and primaries to the rear). My opinion wiith my previous experience and problems.

[Michael C Henry]

Ok I'm stumped .Nice day I got the car outside warmed her up set the floats idles ,etc. ten minute warm up and drive towards the freeway .As I approach the freeway ,it's missing.It gets worse as I limp it home. The venturies aren't fuming anylonger.What next? I have the primary idle screws just barely open secondary stop screws are just barley off their stop idle is around 700-800. carries 9 inches of vacume at idle .4.5 pvs cruis vacume is 10 and above can actually accelerate without droping below 9..It felt great at first but that went away quickly.I need to take it to sombody and say here fix it.