'69 427 "Starter kick back"

[Stuart F.]

Re: '69 427 "Starter kick back"

This is not a problem exclusive to Holley carbs or big blocks. Recently, I was struggling with the timing issue on my 63 with an AFB Carter and, right in the middle of distributor testing, the passenger side float (needle and seat) decided to hang up and flood the engine I was just in the middle of setting the idle speed and emulsion screws, when I goosed the throttle pand noticed a large cloud of blue/black smoke out both tail pipes. I stopped the engine and realized what was happening. I removed the carb and found the inner manifold and base gasket wet with fuel. Upon removal of the top plate, I found the passenger side chamber fuel level way higher than that on the driver's side.

This is not the first time I've been forced to change the oil due to fuel dilution. Back when I had severe hot soak problems and percolation (fuel dripping out of the clusters, etc.), I noticed an increase in oil level on the dip stick, so changed the oil. My local Advance Automotive store refused my drain oil due to the smell of gas in it. I no longer have those issues, but I learned to watch for the fuel dilution situation which saved me this time once again. I've since replaced the needle/seats with Tomco inlet valves and dropped my float levels still further and all seems well on that front.

Stu Fox

[Steve G.]

Re: '69 427 "Starter kick back"

This is not a problem exclusive to Holley carbs or big blocks. Recently, I was struggling with the timing issue on my 63 with an AFB Carter and, right in the middle of distributor testing, the passenger side float (needle and seat) decided to hang up and flood the engine I was just in the middle of setting the idle speed and emulsion screws, when I goosed the throttle pand noticed a large cloud of blue/black smoke out both tail pipes. I stopped the engine and realized what was happening. I removed the carb and found the inner manifold and base gasket wet with fuel. Upon removal of the top plate, I found the passenger side chamber fuel level way higher than that on the driver's side.

This is not the first time I've been forced to change the oil due to fuel dilution. Back when I had severe hot soak problems and percolation (fuel dripping out of the clusters, etc.), I noticed an increase in oil level on the dip stick, so changed the oil. My local Advance Automotive store refused my drain oil due to the smell of gas in it. I no longer have those issues, but I learned to watch for the fuel dilution situation which saved me this time once again. I've since replaced the needle/seats with Tomco inlet valves and dropped my float levels still further and all seems well on that front.

Stu Fox

Stu,

Flooding carbs is not something unique to Holley, it's the leaking between the metering block and body that is unique. And what's particularly troublesome about that is that the bowl can drain into the engine just sitting there, without having to pump fuel up to it.

The major difference between the Holley and most other carbs, including your AFB is that in the others there is no exit for the fuel from the bowl except to go up and over the spill point. That means you have to be pumping fuel into it in order for the fuel to go over the top. If it's running when this happens the engine will stall out long before it hydraulic locks and hurts itself. Yes, you can dilute the fuel and that happens lots, but that's not often fatal and the damage much easier to detect. But that wasn't the situation here. In this case it filled the cyl with fuel then tried to compress it. The potential for damage has nothing to do with diluted lubricant, it is trying to compress a liquid that hurts the hard parts.

Steve

[Stuart F.]

Re: '69 427 "Starter kick back"

Steve;

I was just trying to make a side to the issue. I'm aware of the Holley problem. I just rebuilt a tri-power set for my son's L-89 69. He too had buck starting issue after the engine sat awhile. His center carb would always be empty and caused long cranks. One of the first things we considered was internal leaks, but could not substantiate this with a plug check. Much of his problem seems to have gone away with his latest tank of fuel (110 octane Sunoco racing fuel at $8.99/gal.). With my 63, I too was concerned about a buck starting issue when I had my distributor problem, but I knew better what was causing that, that being too far advanced at the time.

This was an interesting thread for many of us with original engines like mine. I'd hate to loose it due to something preventable.

Stu Fox

[Joe C.]

Re: '69 427 "Starter kick back"

I have heard that the Holley 3659/3660 as well as other 2bbl carbs have a design issue where heat soak causes the needle to unseat when the fuel vaporizes in the supply line. The fulcrum arm of the float is too short. Not only does the fuel in the bowls get pushed into the intake, but so does much of the fuel in the line between the pump and the carb inlets. Add to that siphoning problems if the car is parked on an incline and you have REAL hydro-lock problems.

[William F.]

Re: '69 427 "Starter kick back"

Steve,

are you saying if you remove a Holley bowl to check needle seat(on internal only adjustable ones for ex.) you should replace metering block gaskets as well as bowl gaskets even if you use correct torque(which I do) on bowl screws?

[Steve G.]

Re: '69 427 "Starter kick back"

Steve,

are you saying if you remove a Holley bowl to check needle seat(on internal only adjustable ones for ex.) you should replace metering block gaskets as well as bowl gaskets even if you use correct torque(which I do) on bowl screws?

Yes, that's exactly what I'm saying. All gaskets, except silicone rubber, are intended for single use only. They are intended to compress into the shape and surface of the mating material. The compression of the block to body gasket is achieved through both the screws near the centre and the bowl screws. Every time you re-tighten the bowl screws you are also re-tightening the the block to the body, except that you are only re-clamping the outside edge. So the outer part of the gasket gets thinner and the inner stays the same. That's why the plate warps. If you always replace the gasket the inner portion compresses to the same degree as the outer and you keep the plate straight.

Steve

[Domenic T.]

Re: '69 427 "Starter kick back"

Just a tid bit about fuel in the oil. Oil dilution was intentionally done on some aircraft engines operating in cold WX. The fuel would evaporate during flight and did not harm the bearings.
On a car, I blew one valve cover off a Pontiac and bulged the pan and other cover. That was from a bad fuel pump that kept pouring fuel into the oil. Also long them fuel in the oil seem to have a chemical reaction that caused a acid to form and would cause the rings to chemically weld in the ring lands. It would look like white powder on the aluminum and impossible to remove the rings.

Dom

[William F.]

Re: '69 427 "Starter kick back"

Steve,
As you probably know, the newer "vintage" carbs form Holley(which I have on my L79 and L36) have some improvements such as reinforcements in areas prone to warping and use the blue gaskets labeled as reuseable. I also use these gaskets when doing a carb rebuild. Wouldn't think you'd have to replace all or any of these when you just remove a bowl once or twice. What say you?

[Steve G.]

Re: '69 427 "Starter kick back"

Steve,
As you probably know, the newer "vintage" carbs form Holley(which I have on my L79 and L36) have some improvements such as reinforcements in areas prone to warping and use the blue gaskets labeled as reuseable. I also use these gaskets when doing a carb rebuild. Wouldn't think you'd have to replace all or any of these when you just remove a bowl once or twice. What say you?

I'd say that's the evidence that this is exactly what has been happening. They knew that guys were re-using the gasket and warping the plates then blaming it all on a poor carb design. Easier to redesign the carb than to change the habits of the buying public.

If you have the components that address this issue I'd say you are safe in doing what you do.
Steve

[Steve G.]

Re: '69 427 "Starter kick back"

I have heard that the Holley 3659/3660 as well as other 2bbl carbs have a design issue where heat soak causes the needle to unseat when the fuel vaporizes in the supply line. The fulcrum arm of the float is too short. Not only does the fuel in the bowls get pushed into the intake, but so does much of the fuel in the line between the pump and the carb inlets. Add to that siphoning problems if the car is parked on an incline and you have REAL hydro-lock problems.

IMHO, more myth based on the "heat soak/perc" urban legend.

Defies logic. What pushes the fuel out of the bowl? You can't pressurize the bowl, it's vented. Overfill the bowl? Where does the fuel come from? The engines not running. If you believe the fuel is vaporizing in the line and pushing the needle off it's seat, doesn't the vapor just enter the bowl and exit through the vent?

Steve

[John M.]

Re: '69 427 "Starter kick back"

I had the same problem on a 69 tri power car. It was on jack stands in the rear while working on the trailing arms; full gas tank.
Came home from work the next night and my wife said "the garage smells awful." Fuel in every cylinder. Scared the devil out of me knowing all the things that could have happened. Changed oil, blew out cylinders and changed all the needle and seats and will never do that again nor park facing downward on steep hills.
Still like the tri power though, hype and all...

[Steven B.]

Re: '69 427 "Starter kick back"

It's been my experience that bad gaskets may allow fuel to drip down directly on the manifold. The only place I can see that fuel would get into the manifold, would be through the curb idle discharge. Is that where it's going?

Steve

[Steve G.]

Re: '69 427 "Starter kick back"

It's been my experience that bad gaskets may allow fuel to drip down directly on the manifold. The only place I can see that fuel would get into the manifold, would be through the curb idle discharge. Is that where it's going?

Steve

My understanding of it is that they don't leak externally because tightening the bowl screws over and over distorts the metering block so that it's outer circumference is tight but the centre is concave on the body side. Fuel to the idle circuit normally has to go up and over the spill height (that's what stops fuel from flowing out of the bowl all on it's own), but with the distorted block plate it cross flows to the idle discharge. Now the passages are all below the level of the fuel and gravity does it's stuff.

Steve