After only two years I find that I need to change out my needle and seats. That seems like a short amount of time, but I guess all the additives in the fuel these days explains the rapid deterioration?
I like that the needle and seat are good ol' Holley parts, available everywhere, and inexpensive, with 4 different manufacturers selling them. Holley made, please, and throw in one of the QuickFuel adjustable secondary diaphrams, the QF nylon float adjustment washers, the accelerator discharge kit, and the idle restrictor kit.
That should do me for a while.

 

What were your symptoms that led you to needing to change the needle and seat?
And yes, the gas and additives play a role, but so does the quality of the modern replacement parts.
Hard to say which one is at fault, or if it’s just both. Probably other mitigating circumstances as well, so maybe others will list some more.

 

I found the level of fuel in the float bowls would drop overnight.

 

Doesn't seem to me that leaking needle and seats would lead to a drop in fuel level in the float bowls .... they reside above the fuel level. Accelerator pump diaphragm or bowl gaskets be my first thoughts.

 

Ha! Yeah, good point. So, if it were the acc. pump diaphragm, that would explain the primary side going low, but there is no acc. pump on the secondary side, and that fuel bowl is dropping overnight as well. Oh, and the only gasket on this carb is the airhorn gasket, aside from the small p. valve gasket and the acc. pump housing gasket, and nothing is leaking from them.

You know, this carb has been going lean lately after a good heat soak. After a 10 minute cool down, the carb jumps to 16-17:1 AFR. And it's a bit hard to start. I never had vapor lock in the summer. Why am I getting it in the dead of winter?

$70 for a rebuild kit!!! $70! For $10 more I can buy a sweet, trick Proform metering block for my Holley and be down the road.

 

I had to look this beast up, I see now, it does have bottom mounted power valves at both ends though, or so it appears. Looks like PV covers underneath. I've never been in one of these new Holleys with integrated float bowls. I might have to try one out now?

 

It is a copy of the old Autolite 4100's that pioneered the annular boosters. Holley paid ford to use the design and marketed the Holley 4010, but it bombed b/c it didn't look like a Holley. Now Holley makes them for Summit and has integrated Holley jets, choke, secondary diaphram, floats, needle and seat assbly, p/valve, acc. pump and changeable air bleeds.

I think I passed along some misinformation. This morning my primary bowl was to the bottom of the window, and the secondary side was full to the top of the window. My carb sits with the secondary side lower than the primary due to angle of the engine. Is it possible to drain from one side to the other? There is no transfer tube. Well, I'd rather have it drain into the secondary bowl than into the intake and engine. No gas in oil, thank goodness.

 

I don't think there would be a way if it has no transfer passage. A tube would be hard to get in place with fixed float bowls, but it's possible they included a passage way in the casting I guess, though I have no idea why they would? I just don't know enough about them. I looked it up again, one place says they have two power valves, another place says none on secondaries. I know I saw picture of bottom with two power valve covers.

 

It is my understanding that the larger models, 750 cfm, have p/v's in the secondary. The 500 and 600 cfm models, do not, although the cover for it is in place. I confirmed that on the Summit site that only the 750 cfm has 2 p/v's, 8.5 in the primary, and 6.5 in the secondary.

 

I see the rebuild kits for this carb are on back order and not available until Feb. 23. Luckily, the acc. pump diaphragm and ck valve are Holley parts so I can get them indivigually, made by Holley. Hoorah.

 

I thought about this thread recently when I found a like new, boxed Holley R84012 600 cfm double pumper in a cabinet. It's a Holley 4010 series from around 2000, it's hardly been used. Someone did remove the inlet needle & seats. I considered using it, but it's got mechanical secondaries with their own power valve and accelerator pump, better suited to a F body with peppy SBF manual I think. I had forgotten I even had it, but it did lead me to do some investigating. Looks like it should be gas tight. I don't see how it would leak, except for those power valve and accelerator pump covers. If I read right, it's the Holley 4010 series from which the Summit M08600VS derives from.

 

For a time Holley paid Ford to use the annular booster design for the Holley 4010. The Holley carb was a copy of the old 50's and 60's Autolite 4100. Then Holley bought the design and redesigned the carb with Holley jets, choke, secondary diaphragm, acc. pump and Holley linkage. So, I guess it is an Autolite/Holley hybrid.
I don't understand how I am losing fuel in the primary bowl. At night the level is mid sight glass. In the morning it is bottom of the sight glass. There doesn't seem to be any leak from the acc. pump cover or the power valve cover. I can't find any leakage. If installing new acc. pump diaphragm and ck valve doesn't stop this problem, I'm getting a 4160 made to a 4150 ready to be installed. It's an 1848, 465 cfm for my 250 hp Iinline 6. I've ordered a new promax metering block, longer bowl bolts, Quick Fuel adjustable secondary diaphragm, an assortment of idle restrictions, and I'm also changing it back to the original hot air choke. With an inline six the carb is hanging off the side of the engine and can stay cold longer than with a v8. The electric chokes open too fast for my engine.

I'm also ordering the kit to install the power valve ck ball. Having to drill in the carb, that makes me sit up and pay attention. Have you ever done that. I'll ck youtube for a video, but I want to get it right the first time.

 

I look at those carbs like yours on the net, videos, I would have thought they were "leak proof". I can only wonder if maybe a crock in the main body if not leaking from a power valve of accelerator pump. Not a crack from impact, but I wonder if maybe heat and cooling?

 

I have an electric rad. fan. The engine temp fluctuates about 10*, from 205* on down to 195* off. I just noticed that when the coolant temp is 200* or more, my AFR is 15:1 at idle.
Man, I'm getting really tired of this carb.

 

So today I took apart my Summit carb. I should say that for 2 years it ran perfectly. But now, something is up. I had noticed that when I opened the top, there were particles at the bottom of the fuel bowls, and I run two filters. Oh well. Before I pulled it it was mysteriously running lean, and wanting to stall now and then. It was time for a rebuild. But I was surprised to find what looks like JB Weld in several of what I assume were factory holes on the bottom of the carb. What concerns me is that I can scrape it with my fingernail or putty knife. I've rebuilt probably 30 carbs, and never have I seen anything like this! I am alarmed. I'm afraid that if I dip it in carb cleaner it will dissolve! It is easy to see in the photos that the substance is protruding above the surface and smudged in places. Shoddy.

I can't remember if this was a totally new carb, or what Summit calls a 'remanufactured' carb. Either way, I think this is mickey mouse crapola beyond belief. I'm going to call Summit and have a talk with them.