Vacuum secondaries vs mechanical secondaries

[barrys65cyclone]

Go with vac secondary it has nothing to do with vacuum engine produces , it is the air flow through carb venturi that opens secondary I have engine 04in that produces 4.5in vac at idle and I run 2 4bbl carbs that are vacuum secondary and they open fine.

[robib]

Think I said that a few posts ago.

[barrys65cyclone]

Think I said that a few posts ago.

you made the correct decision

[Lou's Comet]

Hey Lou the Falcons 302 is running a smallish .540 lift mechanical flat tappet cam with 290 duration. It’s pretty lumpy and I run a Holley 650 HP double pumper. No choke and a “race” calibration. Driving around town with a dual point distributor, mechanical secondaries, race valved Bilsteins, and a 4 speed is actually pretty fun
And of course mashing the sandal down on the track gets you all the gas you need NOW.
I’m ok with the user controlled secondaries- street or track.
I like this one https://www.holley.com/products/fuel_sy ... 0-80803BKX

Joe

Wow that is one good looking carb!! Was really hoping to get one a little cheaper tho

I am sure driving the Falcon around town is fun.

I was thinking of no choke but seen where there were some concerns with washing the cylinder walls with gas when not using a choke. But not sure. I live in Pa and in the spring and fall a choke may be nice. If I go with a choke it will probably be manual/cable.

Thanks for the help Joe!!

Lou

[Lou's Comet]

Thanks everyone for the help. After hearing what you guys said, talking to my builder and talking to my friends I have decided to go with mechanical secondaries. Going to go with a 750 cfm. Still a lot of choices, not sure if I will go with a choke or not. If I do go with a choke I am thinking manual. But would like to skip choke all together if I could.

Thanks again for the input, I appreciate it!

[comethead]

Hey Lou I see where that could be a concern. No choke, car wont start…pump the gas too much and get that theoretical cylinder wash.
Strange but true- that stinkin Falcon of mine starts real fast without a choke, even when I took it to the track in 29 degree weather!
But my Comets Autolite 4100 with a manual choke does not like to start cold and it takes quite a few pump shots to get her to go


Joe

[Joe Travers]

Strange but true- that stinkin Falcon of mine starts real fast without a choke, even when I took it to the track in 29 degree weather!
But my Comets Autolite 4100 with a manual choke does not like to start cold and it takes quite a few pump shots to get her to go

You have 50cc pumpers on your race carb, Joe?
If my Comet sits for a while, I have to pump it to fire off, especially in cold weather.
Going up on squirter nozzle size from 31 to 35.

Joe II

[comethead]

Hey Joe the carb has 30cc pumpers.
Not sure why it starts so darn well when cold and my Comet doesn’t. Maybe because everything is new?
Ive let the Comet sit for a while and Ive taken off the air cleaner and pumped the throttle. There is fuel in the bowls even after sitting for a week or two. So it isn’t the gas somehow drying out of the carb. Maybe the fuel in the line drains back to the tank? Intake issue? Who knows.
The only way I’ve found that works is to start it and drive it a lot

[Jims65cyclone]

I've got an Edelbrock on mine, and if sits for a couple weeks it takes 3 - 4 tries to get it to crank. Once it cranks, I can crank it again anytime within the next 4 - 5 days on the first spin. I've wondered if its just an Eddy thing because Pop has said his does the same thing, and he's got two Eddys on his. Like you said, Joe, I just need to drive it more often and the problem will go away.

Jim

[Joe Travers]

Hey Joe the carb has 30cc pumpers.
Not sure why it starts so darn well when cold and my Comet doesn’t. Maybe because everything is new?

My guess, racing fuel in Falcon, ethanol in Comet.

Joe

[popscomet]

I've got an Edelbrock on mine, and if sits for a couple weeks it takes 3 - 4 tries to get it to crank. Once it cranks, I can crank it again anytime within the next 4 - 5 days on the first spin. I've wondered if its just an Eddy thing because Pop has said his does the same thing, and he's got two Eddys on his. Like you said, Joe, I just need to drive it more often and the problem will go away.

Jim

And I have the same eddys on my cobra,,,it does the very same thing...must be an eddy thing.pop

[Joe Travers]

And I have the same eddys on my cobra,,,it does the very same thing...must be an eddy thing.pop

My Holley same thing, Pop. Thinks it's the corn squeezins in the tank

Joe

[comethead]

Hey Joe the carb has 30cc pumpers.
Not sure why it starts so darn well when cold and my Comet doesn’t. Maybe because everything is new?

My guess, racing fuel in Falcon, ethanol in Comet.

Joe

Good point Joe! I didn’t even think of that. I use 91 octane gas with Ethanol in the Comet. Falcon gets $10/gallon 101 octane VP Racing gas

[popscomet]

I have a 600 holly on my 66 f100 with a 390,,never have to pull the manual choke out,,just pat the pedal 1or2 times,,,busts right off,,after sitting for weeks,,,sometimes I will pull the cable out just enuff to bump the fst idel ,,,if I'm going to walk away from it and leave it running to warm up ,,,those 2 eddy's on the comet as soon as it starts,,it's ready to go,,just take off and go,,,,but the 2 on the cobra are very cold natured,til they warm up,,,,nothing I own with carbs get started or driven very often anymore,,,my comet has been in the shop on the lift close to 2mos,,,when I get ready to start it,,will remove the front air cleaner and pour some gas down it to start it,,,it has a manual fuel pump so the whole fuel system has to get primed,,,but on the cobra Ill spin the engine over a couple of times to build oil pressure so's the electric pump will come on,,,,it has a low oil pressure switch wired in to turn the pump on,,,,,I do not have the chokes workable on the eddys,,never have,,,I too need to start and drive them more,,,,thanks pop

[Joe Travers]

I use 91 octane gas with Ethanol in the Comet. Falcon gets $10/gallon 101 octane VP Racing gas

I run 93 in the Comet. Wish I could pull up to the airport and fill up but av fuel isn't taxed for road use.

Joe II