C2 - Holley 3810 Advice

[67ragtop]

I had my original Holley 3810 rebuilt 9 months ago but it never worked quite right, even after several trips back to the shop. It would leak fuel into the manifold after it had been run and parked. This would not only stink-up my garage but made it difficult to start, most likely not good for the motor & maybe even some safety issues. Using that strategy and a desire to keep things original, I justified the $$$ for a new Holley 3810.

Everything seemed fine for the first 1,000 miles. A few weeks ago the same old problem came back. It started off with a slight smell but is now quite strong. There are no signs of any fuel leakage above the butterflies yet the manifold is very wet inside. Now I'm wondering if this was a common problem with the 3810 or is there something else wrong? There doesn't seem to be any pressure in the gas tank when removing the cap and the fuel pump was replaced.

Since my car is original (67 sb 350hp), I really didn't want to make any modifications fitting a new style carb to it but I'm thinking I may have to go that route. Is there a better choice available with minimal modifications?

Any advice or recommendations would be greatly appreciated.

 

[IH2LOSE]

I am not so falmilur with your carburator.but I honestly feels holleys in general stink.The average shop can not rebuild the carbs so well they just dont have the proper tools.

There is a fellow named Jerry Luck out of hazelwood MO 314-895-1551 this guy rebuild carburators he machines all of the surfaces true and flathe realigns the bores proper when his is done with you carb it is better then new ( I really mean better then new he re machines everything.He aslo can recolor/replate it to ncrs specs.

there is also anothe fellow name jery macneish http://www.z28camaro.com/restosvcs.html

allthough I never used his carb service I did have hime restore some aluminum parts and they were PERFECT!

Good Luck

 

[allcoupedup]

Are the floats levels adjusted properly?
Brian

 

[67ragtop]

I am not so falmilur with your carburator.but I honestly feels holleys in general stink.The average shop can not rebuild the carbs so well they just dont have the proper tools.

There is a fellow named Jerry Luck out of hazelwood MO 314-895-1551 this guy rebuild carburators he machines all of the surfaces true and flathe realigns the bores proper when his is done with you carb it is better then new ( I really mean better then new he re machines everything.He aslo can recolor/replate it to ncrs specs.

there is also anothe fellow name jery macneish http://www.z28camaro.com/restosvcs.html

allthough I never used his carb service I did have hime restore some aluminum parts and they were PERFECT!

Good Luck

I have a drag racing friend that feels the same way about Holley's.

After several attempts to fix my original, I believed there was something warped causing the problems. A brand new carb however, should not have that problem.

I've used Jerry M. to restore my aluminum valve covers and I agree, he does great work.

 

[67ragtop]

Are the floats levels adjusted properly?
Brian

Brian,

I really don't know. When I took the original back they suspected the floats might be causing the problem and adjusted them (twice).

I'm assuming the new carb came from the factory correct?

Mike

 

[allcoupedup]

Mike,
It's an easy enough check. With the engine running, remove the plug - when set correctly the fuel should be just barely dribbling out of the hole. I usually place a paper towel under the plug sp it doesn't run all over.

Give it a try!
Brian

 

[MMM]

I recommend setting the floats a slightly low. You are experiencing heat transfer from the manifold to the carb (heat sink) after you shut the engine down. This heat causes the fuel in the bowls to expand and consequently both leak out of the carb and into the engine through the venturis.
Holley floats are best set on the car with the engine running, at operating temperature and the choke off. It is messy job thought and I never felt safe doing it (but I always do it that way). It is not the fuel sloshing out of the float level hole that bothers me, but the fuel that sprays from the screw that locks the adjustable needle valve in place. Never figured a way to do this neatly and I fear atomized gasoline over a hot and running engine. Adjust the floats so the fuel level is approx. 1/16' below the gauge port in the bowl.
This is why I like Q-Jets. They don't leak nearly as badly as Holleys and if properly adjusted work just as well. I have seen too many engine fires caused by leaking Holley carbs.
Mike

 

[67ragtop]

Mike,
It's an easy enough check. With the engine running, remove the plug - when set correctly the fuel should be just barely dribbling out of the hole. I usually place a paper towel under the plug sp it doesn't run all over.

Give it a try!
Brian

Not as easy as it sounds. The Holley 3810 does not have an external adjustment for the floats or a sight plug. I believe the bowls must be removed and the floats are simply bent for fine adjustments, kinda like my lawn mower?

 

[allcoupedup]

My bad.... thought they all had external adjustments. Sounds like my old AFB! I still think this should be the first place to check.

Brian

 

[Sams '66]

I had the same problem.......boxed up the original....replaced with a new one.......still leaks sometimes.....but not as bad.
Wish I had a fuelie.......

 

[67ragtop]

I recommend setting the floats a slightly low. You are experiencing heat transfer from the manifold to the carb (heat sink) after you shut the engine down. This heat causes the fuel in the bowls to expand and consequently both leak out of the carb and into the engine through the venturis.
Holley floats are best set on the car with the engine running, at operating temperature and the choke off. It is messy job thought and I never felt safe doing it (but I always do it that way). It is not the fuel sloshing out of the float level hole that bothers me, but the fuel that sprays from the screw that locks the adjustable needle valve in place. Never figured a way to do this neatly and I fear atomized gasoline over a hot and running engine. Adjust the floats so the fuel level is approx. 1/16' below the gauge port in the bowl.
This is why I like Q-Jets. They don't leak nearly as badly as Holleys and if properly adjusted work just as well. I have seen too many engine fires caused by leaking Holley carbs.
Mike

Mike,

Your reply about the heat makes sense. I tried running the engine (cold) for 5 minutes then shut it off, closed up the garage and let things sit for about 30 minutes. When I returned, there was no smell of raw gas in the garage. The general consensus seems to point at the float level however; I'm not sure how to properly adjust it since there's no external adjustments?

Mike

 

[Mac]

I'm assuming the new carb came from the factory correct?

Mike

Mike, the factory rebuilds old carbs as well so there's no guarantee that your "new" carb is new unless it said so specifically on the box. From what I understand, failures from the factory rebuilts are relatively common.

Did you retain your original carb? I would send it to Jerry or Jerry and get it redone properly.

-Mac

 

[Firemist1]

I had the same problem over the years with the Holley on my '67. Finally bought a new 3810 thinking that would solve the problem, but before long I was rebuilding the carb every 12 months to stop the leaking into the secondaries. I tried truing up mating surfaces, replacing metering blocks, etc. but nothing worked. Each time I disassembled the carburetor there was no indication of anything wrong, but when boiled out in carburetor cleaner, it would work fine for a year. After much frustration, I added a can type Napa fuel filter in the hose between the frame and suction side of the fuel pump and that has permanently fixed the problem. Those small fuel filters in the inlet are just too porous and they let small particles of dirt through that eventually gets into the secondary float bowl and metering block causing a leak. Just my 2 cents worth.

 

[Sams '66]

I had the same problem over the years with the Holley on my '67. Finally bought a new 3810 thinking that would solve the problem, but before long I was rebuilding the carb every 12 months to stop the leaking into the secondaries. I tried truing up mating surfaces, replacing metering blocks, etc. but nothing worked. Each time I disassembled the carburetor there was no indication of anything wrong, but when boiled out in carburetor cleaner, it would work fine for a year. After much frustration, I added a can type Napa fuel filter in the hose between the frame and suction side of the fuel pump and that has permanently fixed the problem. Those small fuel filters in the inlet are just too porous and they let small particles of dirt through that eventually gets into the secondary float bowl and metering block causing a leak. Just my 2 cents worth.

This makes more sense than anything that I have heard yet.....not NCRS, but WHO CARES!! I am going to do it.

 

[MMM]

67 Ragtop,
You are correct, the 3810 does not have the externally adjustable floats. I was picturing the wrong carb (the holley used on the '66 327/350) in my mind. what happens when you get old.
Yes, the only way to adjust the floats is to remove the fuel bowls and bend the float "tangs". Not really a hard job and is less messy than external adjustment. Just remove one of the lower bowl screws first and drain the bowl through the screw hole.
If you try this yourself, I recommend you purchase a set of bowl and bowl hold down screw gaskets (available in almost any parts store) and replace these parts. You can find the correct float level from the Holley web site under "technical Info". I would start by setting them 1/16' lower than recommended. You need to interpret this correctly, because a lot of Holleys gage the float level distance by measureing it to the TOP of the bowl. If this is the case with your carb, then you need to INCREASE the distance from the top of the float to the top of the bowl to LOWER the float(s).
Good Luck,
Mike

 

[Firemist1]

This makes more sense than anything that I have heard yet.....not NCRS, but WHO CARES!! I am going to do it.

The NAPA number for the fuel filter I use is 3003. It is 3/8" inlet and outlet to fit the hose and is the clear see through design. They also make the solid steel version; I just like to see what's going on inside my fuel system. If you cut the hose approximately half way between the frame & fuel pump, the filter will fit next to the frame and down and away from the manifold. You can always replace the hose easily for that NCRS look. Be careful when you cut the hose since its level is below the fuel tank and you will see a free flow of gasoline. Just be prepared to pinch it off quickly. Good luck. I can take pictures if you want them.

 

[Sams '66]

The NAPA number for the fuel filter I use is 3003. It is 3/8" inlet and outlet to fit the hose and is the clear see through design. They also make the solid steel version; I just like to see what's going on inside my fuel system. If you cut the hose approximately half way between the frame & fuel pump, the filter will fit next to the frame and down and away from the manifold. You can always replace the hose easily for that NCRS look. Be careful when you cut the hose since its level is below the fuel tank and you will see a free flow of gasoline. Just be prepared to pinch it off quickly. Good luck. I can take pictures if you want them.

Pictures would be GREAT!

 

[ctjackster]

you could also go with a more correct-looking (but "wrong" for a 66) GF90 fuel filter set up, such were used on 63 - 65 SHP apps and are available from all of the sources, as well as the plumbing bits and brackets

 

[Grizzly]

On my 300/327 had similar but worse. Wouldn't idle right, wouldn't run right. Had it rebuilt, still a problem. Passed car, fuel goes down, floats stick open and drowns the engine and I can't start it. Gas everywhere, scares me! Got a 650 Barry Grant Road Demon and it runs like a champ. No fuss, no bother. I would recomend it to anyone.

 

[kobi67]

67ragtop, I just went thru the same thing on my 67. I had fuel standing in the intake and saw it leaking out the secondary throttle shaft. It would also make an mess on the intake, stains running down the sides.. Only after the car sat after a hot-soak. I went and got a set of gaskets for both bowls and metering blocks. I also replaced the power valve, while I was in there. So far, no leaks...I did use the blue reuseable non stick gaskets. I figure I'll be in it again... I was told that the needle and seats are not available??? I really thought it was the fuel pressure building on a hot soak and pushing fuel past the needle and seat.
Maybe, I was wrong?? I have run the car 6-8 times so far, no leaks. Hope this helps... Kurt