Summit 600 CFM Carb

[85lebaront2]

John - I've now read all the posts on that thread and I see 3 guys that say it is an Edelbrock issue. But they don't say why they believe that, nor any facts to support that belief. (Then there's you, and you are having the problem but don't know if it is due to having an Eddy.)

If a carb is dry after a period of time then there are only two explanations - leakage and evaporation. So let's break this down and think logically about what the issue might be:

• Leakage: It is unlikely that the Eddy is leaking because it is the only one of the traditional carbs (Eddy, Holley, Autolite) being discussed that have no gaskets or fabric holding the fuel in. The Eddy is all metal where the fuel is.

• Evaporation: This is probably the area where an Eddy comes in last, or first depending on how you think, as the Eddy has a wide fuel bowl so the gas has more surface area than that in a Holley or similar design carb which has taller bowls. But I think the Autolite might be closer to the Eddy than the Holley due to the shape of the carb.

Reducing heat, which contributes to the evaporation, is obviously a good approach. But you said you already have the Eddy heat spacer, so there's not much left to do there.

What gas are you running? Straight gas or ethanol? The latter evaporates faster than gas does. And, you could add a fuel stabilizer to the fuel.

Bottom Line: I can see why gas in an Eddy might evaporate faster than gas in a Holley - surface area. But I don't know that going to an Autolite will be that much better since I don't really know how much surface area their bowls have.

Gary, last time I looked, Autolite/Motorcraft 2100/2150 carbs along with the 4100 do not have a gasket sealing gas in, they, like a Carter have a top cover with a gasket.

The Carter AFB and AVS, and even the Thermoquad have long narrow bowls on the sides, where Holley and Autolite have end bowls, that depending on actual design and float size/shape, may or may not hold more gas than a Carter. The old Holley cork bowl gaskets were terrible if they dried out, next time the bowl(s) filled up, they would leak like a sieve.

[Gary Lewis]

Gary, last time I looked, Autolite/Motorcraft 2100/2150 carbs along with the 4100 do not have a gasket sealing gas in, they, like a Carter have a top cover with a gasket.

The Carter AFB and AVS, and even the Thermoquad have long narrow bowls on the sides, where Holley and Autolite have end bowls, that depending on actual design and float size/shape, may or may not hold more gas than a Carter. The old Holley cork bowl gaskets were terrible if they dried out, next time the bowl(s) filled up, they would leak like a sieve.

Bill - What are power valves made of? FABRIC. Which is why I said "because it is the only one of the traditional carbs (Eddy, Holley, Autolite) being discussed that have no gaskets or fabric holding the fuel in."

I'm not saying that leakage is a problem with the others. I'm just saying it isn't likely to be with an Eddy. So that can't be why an Eddy may be losing gas.

Anyway, do you think the Eddy has more surface area than a Holley or Autolite?

[Rembrant]

That said, I've read raving reviews on this Summit 600 CFM carb. It is made by Holley but designed around the Ford 4100 series carbs, which were great.

Anybody running one of these?

I have the 500CFM version on my newly built 302, but it's not running yet.

https://www.summitracing.com/parts/sum-m08500vs

I've been intrigued with this carb based on some of the stuff I've read about Rick's comments over the years. My 302 is very mild, and it'll just be a cruiser so I thought the little 500CFM carb would be a nice fit. I can't wait to get it fired up and running...hopefully in another month or so.

I just installed a Holley TPS on it recently to signal my Quick4 transmission controller.

Here it is with the hard supply line removed and TPS installed.

 

[Machspeed]

That said, I've read raving reviews on this Summit 600 CFM carb. It is made by Holley but designed around the Ford 4100 series carbs, which were great.

Anybody running one of these?

I have the 500CFM version on my newly built 302, but it's not running yet.

https://www.summitracing.com/parts/sum-m08500vs

I've been intrigued with this carb based on some of the stuff I've read about Rick's comments over the years. My 302 is very mild, and it'll just be a cruiser so I thought the little 500CFM carb would be a nice fit. I can't wait to get it fired up and running...hopefully in another month or so.

I just installed a Holley TPS on it recently to signal my Quick4 transmission controller.

Here it is with the hard supply line removed and TPS installed.

Gary, I think there are more than three guys on there saying that or at least confirming that this is "typical" with the Edlebrock. Curious, you have one on your truck. If you go more than a week, does it fire right up or do you have to crank on it for a bit? The longer I wait between starts, the longer it takes me to start my truck too, so I know there is no fuel in that carb. It's really not that big of a deal for me as the truck runs fine. Once started, it will fire right up easily and repeatedly. It idles nicely too! I brought my hard starts up because it is something that was said does not happen with the Summit Carb??? Also, it has the annular discharge and I've read all kinds of raving reviews on it. Not sure I'm going to get one, but am very curious about it. A rebuild kit for it is $85 though.....ouch!

[Gary Lewis]

Gary, I think there are more than three guys on there saying that or at least confirming that this is "typical" with the Edlebrock. Curious, you have one on your truck. If you go more than a week, does it fire right up or do you have to crank on it for a bit? The longer I wait between starts, the longer it takes me to start my truck too, so I know there is no fuel in that carb. It's really not that big of a deal for me as the truck runs fine. Once started, it will fire right up easily and repeatedly. It idles nicely too! I brought my hard starts up because it is something that was said does not happen with the Summit Carb??? Also, it has the annular discharge and I've read all kinds of raving reviews on it. Not sure I'm going to get one, but am very curious about it. A rebuild kit for it is $85 though.....ouch!

I have EFI on Big Blue, and it starts right up every time, regardless of how long it has been sitting, how cold or hot it is. But I ran an Eddy on it, as well as on Dad's truck and Rusty, for a few years. And yes, after they sat for a few weeks they had to crank to start. But that's not unusual in my experience, regardless of what carb I've been running.

[Machspeed]

I have EFI on Big Blue, and it starts right up every time, regardless of how long it has been sitting, how cold or hot it is. But I ran an Eddy on it, as well as on Dad's truck and Rusty, for a few years. And yes, after they sat for a few weeks they had to crank to start. But that's not unusual in my experience, regardless of what carb I've been running.

LOL....how could I forget that you went to fuel injection. Sorry, Gary!

[Gary Lewis]

LOL....how could I forget that you went to fuel injection. Sorry, Gary!

No problem, John. You can't remember everything.

[85lebaront2]

Bill - What are power valves made of? FABRIC. Which is why I said "because it is the only one of the traditional carbs (Eddy, Holley, Autolite) being discussed that have no gaskets or fabric holding the fuel in."

I'm not saying that leakage is a problem with the others. I'm just saying it isn't likely to be with an Eddy. So that can't be why an Eddy may be losing gas.

Anyway, do you think the Eddy has more surface area than a Holley or Autolite?

True on the fabric (rubberized) power valves. As for losing gas, I had a very nice little AFB on a 312 Thunderbird special in my 1958 F100. It was from a 1964 or 65 Buick 300 ci V8 and was a great match for the 312. I had two issues with it, first I was getting gas showing up on the right side around the throttle shafts and on a cold start it acted like it was only running on 4 cyls. I finally decided to carefully remove it and sit it on a large can. Gas would very slowly drip out of the right side due to a hairline crack in the bottom of the right float bowl.

I wound up putting a 292 2 barrel intake and a non-feedback VV carb on. 25 mpg using the OD on a 312 with the truck's 3.70 gear.

[Gary Lewis]

True on the fabric (rubberized) power valves. As for losing gas, I had a very nice little AFB on a 312 Thunderbird special in my 1958 F100. It was from a 1964 or 65 Buick 300 ci V8 and was a great match for the 312. I had two issues with it, first I was getting gas showing up on the right side around the throttle shafts and on a cold start it acted like it was only running on 4 cyls. I finally decided to carefully remove it and sit it on a large can. Gas would very slowly drip out of the right side due to a hairline crack in the bottom of the right float bowl.

I wound up putting a 292 2 barrel intake and a non-feedback VV carb on. 25 mpg using the OD on a 312 with the truck's 3.70 gear.

Bill - The Buick 300 came out in '64. We had one with the Super Turbine 300 with the switch-the-pitch feature. Man, that thing would RUN! Right up until the water Dad was using as coolant ate the aluminum heads. Took it into the dealership and they wouldn't stand behind it - seems I'd beaten the shop foreman's son in a drag a couple of days before.

Anyway, yes a crack in the casting will cause them to leak. But that's about all that will do it. (Unlike others that have gaskets or fabric, and some that had plugs in the drilled passages that leaked. ) But I've not had a Carterbrock leak due to that, and I've run a few.

[FordFETruck]

Bill - The Buick 300 came out in '64. We had one with the Super Turbine 300 with the switch-the-pitch feature. Man, that thing would RUN! Right up until the water Dad was using as coolant ate the aluminum heads. Took it into the dealership and they wouldn't stand behind it - seems I'd beaten the shop foreman's son in a drag a couple of days before.

Anyway, yes a crack in the casting will cause them to leak. But that's about all that will do it. (Unlike others that have gaskets or fabric, and some that had plugs in the drilled passages that leaked. ) But I've not had a Carterbrock leak due to that, and I've run a few.

Just some feedback with the summit carbs. I own two of them. The 600 CFM variant (I would have bought the 500 CFM if they offered it back then) I bought for my truck 10 years ago. Never had a problem with it, and it had the original power valve in it for like 8 years before I swapped it out for the correct HG rating for the engine and it was still like new. I have done some tuning to it with the help of a wideband o2 AFR gauge and got it all spot on and put a Motorcraft 7 volt choke cap on it. Starts right up and runs fantastic in cold or hot weather.

I like it so much I replaced my extensively tuned 600 CFM Holley on my 64 galaxie 390 with a 500, yes 500 CFM Summit carb on that big engine. I tuned it to the application with the help of a wideband o2 AFR gauge and put a 7 volt Motorcraft choke cap on it also and I'll be darned if it didn't pick up torque and throttle response below 2000 RPM and scream just as hard to 5500-6000 as the 600 CFM Holley did. Both can sit for over a week and fire right up with just a few squirts of the accelerator. I really like both of mine.