Prime Demon 1900 Carburetor

-
LS&S

LS&S

Well-Known Member
Joined
Jun 9, 2019
Messages
53
Reaction score
27
Location
Aylett, VA
The carburetor directions say to spin the engine with the starter for 30 seconds to prime the carburetor. The problem is that if I do that, I'll wipe most of the lubricant off my camshaft lobes. Is there a way to prime this carb without spinning the engine over?
Thanks. All help appreciated.
 
LS&S said:
The carburetor directions say to spin the engine with the starter for 30 seconds to prime the carburetor. The problem is that if I do that, I'll wipe most of the lubricant off my camshaft lobes. Is there a way to prime this carb without spinning the engine over?
Thanks. All help appreciated.
Click to expand...

Get a squeeze bottle with gas and pour down the vent tube to fill the bowls. That’s enough to get the motor running for the pump to supply to the carb.
 
LS&S said:
The carburetor directions say to spin the engine with the starter for 30 seconds to prime the carburetor. The problem is that if I do that, I'll wipe most of the lubricant off my camshaft lobes. Is there a way to prime this carb without spinning the engine over?
Thanks. All help appreciated.
Click to expand...


I’d burn those directions.
 
If you've got a mechanical fuel pump, prime it like Scody21 said, then fire it up.
If you've got an electric fuel pump, it's a non-issue. Ignition to "on" for a few seconds to get fuel in the carb, then crank it up.
 
Scody21 said:
Get a squeeze bottle with gas and pour down the vent tube to fill the bowls. That’s enough to get the motor running for the pump to supply to the carb.
Click to expand...
Professor Fate said:
If you've got a mechanical fuel pump, prime it like Scody21 said, then fire it up.
If you've got an electric fuel pump, it's a non-issue. Ignition to "on" for a few seconds to get fuel in the carb, then crank it up.
Click to expand...
He's got a 1900, the street demon thermoquad lookalike. No vent tubes, its not a holley derivative.
Pull the fuel line, get a squirt bottle and try to slowly squirt some fuel past the needle and seat.
But like said above, with an electric pump, just turn the pump on.
 
RustyRatRod said:
It's not gonna hurt a thing for 30 seconds. Couple of fifteen second bursts......three ten seconds......


I know that's right.
Click to expand...


The biggest killer of roller lifters is guys cranking on the engine to build oil pressure. It beats the hell out of the needles. Convincing some of those guys to not do that was hard. Some never learned.

I’m sure the OP isn’t running 300 plus pounds of spring load on the seat, but it’s be habit to get into. And pretty reckless to tell the end user to do it when every carb in the world has vent tubes to get enough fuel in the bowls to fire it off.

What’s funny is my high school shop teacher used to use starting fluid to crack off fresh engines. I didn’t care for that either, because they run on detonation doing it that way. He was flabbergasted when I asked him (in front of the whole class) why he didn’t just put some fuel in the bowls. His answer? Because that’s the way my high school shop teacher and the US Army taught him how to do it.

After that, he started filling the bowls through the vents. He was a great teacher and a decent guy. Many times he could have busted my *** for things I was doing but he let me have pretty much free range to work on other people’s cars for money during class time. Stuff like that. Very cool guy.
 
33IMP said:
He's got a 1900, the street demon thermoquad lookalike. No vent tubes, its not a holley derivative.
Pull the fuel line, get a squirt bottle and try to slowly squirt some fuel past the needle and seat.
But like said above, with an electric pump, just turn the pump on.
Click to expand...


There has to be a vent somewhere or the carb won’t work. I need to go find a picture to see what they look like.
 
33IMP said:
He's got a 1900, the street demon thermoquad lookalike. No vent tubes, its not a holley derivative.
Pull the fuel line, get a squirt bottle and try to slowly squirt some fuel past the needle and seat.
But like said above, with an electric pump, just turn the pump on.
Click to expand...


FYI the vents are to the outboard side of the metering rods on the Street Demon 1900.
 
yellow rose said:
The biggest killer of roller lifters is guys cranking on the engine to build oil pressure. It beats the hell out of the needles. Convincing some of those guys to not do that was hard. Some never learned.
Click to expand...

That very method is how the Blueprint Engines Installation Guide says to do it. Quote: "Your engine has been pre-lubed and dyno tested but requires additional preventative maintenance before initial startup. Fill oil filter and oil pan to recommended capacity. Verify the ignition source does not have power. This will eliminate the possibility of any fuel in the cylinders igniting prematurely. Remove spark plugs and proceed to crank engine over with starter until oil pressure is visible on manual gauge. Do not supply fuel to the engine during this process. WARNING: Failure to prime this engine can cause premature bearing damage. Reinstall spark plugs and proceed with initial startup."
 
If you think for one second thirty seconds or "however long" it takes to fill the fuel bowl up will wipe the break in lube off the cam, you probably used the wrong stuff, or installed it dry.
 
RustyRatRod said:
If you think for one second thirty seconds or "however long" it takes to fill the fuel bowl up will wipe the break in lube off the cam, you probably used the wrong stuff, or installed it dry.
Click to expand...
I've been doing it that way on every engine I've ever built and had zero issues whatsoever.

Edit: I never used a manual gauge, but removed a valve cover and cranked until I saw oil coming up through the shaft and around the rockers.
 
Last edited:
Ricks70Duster340 said:
I've been doing it that way on every engine I've ever built and had zero issues whatsoever.
Click to expand...

Yes sir. I will say this......I've gotten into the habit now of turning the regulator down on the compressor to like 5PSI, putting a rag around my air blower and pressurizing the tank. Does the same thing after a minute or two and you're testing the fuel system for leaks before you spin the engine or throw fire to it. But there's nothing wrong with spinning it either. If there was, Blueprint wouldn't risk a warranty engine by telling you to do it in the deestruckshuns.
 
RustyRatRod said:
Yes sir. I will say this......I've gotten into the habit now of turning the regulator down on the compressor to like 5PSI, putting a rag around my air blower and pressurizing the tank. Does the same thing after a minute or two and you're testing the fuel system for leaks before you spin the engine or throw fire to it. But there's nothing wrong with spinning it either. If there was, Blueprint wouldn't risk a warranty engine by telling you to do it in the deestruckshuns.
Click to expand...
Agree completely. Good idea about pressurizing the tank to push fuel to the carb. Never thought of that!
 
On dry sump oil systems with belt driven external oil pumps they spin faster and thus make oil pressure in a very short amount of time.

On cam driven oil pumps like most of us run, when turning the motor over with the starter the cam is driving the pump at 1/4 the revs as compared to the crank, thus not building the oil pressure as quickly as just firing the motor off.

Best thing is just pull the distributior, and drive gear, putting the prime rod in and spin with a drill to prime the oil system.
 
Scody21 said:
On dry sump oil systems with belt driven external oil pumps they spin faster and thus make oil pressure in a very short amount of time.

On cam driven oil pumps like most of us run, when turning the motor over with the starter the cam is driving the pump at 1/4 the revs as compared to the crank, thus not building the oil pressure as quickly as just firing the motor off.

Best thing is just pull the distributior, and drive gear, putting the prime rod in and spin with a drill to prime the oil system.
Click to expand...

We're more talkin about priming the carburetor.
 
Scody21 said:
On dry sump oil systems with belt driven external oil pumps they spin faster and thus make oil pressure in a very short amount of time.

On cam driven oil pumps like most of us run, when turning the motor over with the starter the cam is driving the pump at 1/4 the revs as compared to the crank, thus not building the oil pressure as quickly as just firing the motor off.

Best thing is just pull the distributior, and drive gear, putting the prime rod in and spin with a drill to prime the oil system.
Click to expand...
I bought a primer shaft from Ed Hamburger's 340 & 360's only way back. My drill never spun the shaft fast enough to bring oil up, so I just did it the old fashioned way!
 
Right next to the metering rods. The vents aren't tubes like the old school carbs.
@33IMP

1900b.jpg
 
Ricks70Duster340 said:
That very method is how the Blueprint Engines Installation Guide says to do it. Quote: "Your engine has been pre-lubed and dyno tested but requires additional preventative maintenance before initial startup. Fill oil filter and oil pan to recommended capacity. Verify the ignition source does not have power. This will eliminate the possibility of any fuel in the cylinders igniting prematurely. Remove spark plugs and proceed to crank engine over with starter until oil pressure is visible on manual gauge. Do not supply fuel to the engine during this process. WARNING: Failure to prime this engine can cause premature bearing damage. Reinstall spark plugs and proceed with initial startup."
Click to expand...


I would never do that or even recommend that procedure. The correct way to prime ANY engine is to pull the distributor and turn the pump with a drill. Or even by hand with a speed wrench.

On some of the newer engines you can’t drive the pump externally so you use a pressurized tank, find an oil port and put pressurized oil to the engine like that.

Killing a cam lobe from cranking an engine isn’t about rubbing the lube off. Setting the lash does most of that anyway.

It’s the ghastly slow turning of the lifters that kills the lobes. Especially if you are using a lobe that wasn’t designed in 1970 or springs that could be used on a very mild lobe.

That’s just bad policy.
 
yellow rose said:
I would never do that or even recommend that procedure. The correct way to prime ANY engine is to pull the distributor and turn the pump with a drill. Or even by hand with a speed wrench.

On some of the newer engines you can’t drive the pump externally so you use a pressurized tank, find an oil port and put pressurized oil to the engine like that.

Killing a cam lobe from cranking an engine isn’t about rubbing the lube off. Setting the lash does most of that anyway.

It’s the ghastly slow turning of the lifters that kills the lobes. Especially if you are using a lobe that wasn’t designed in 1970 or springs that could be used on a very mild lobe.

That’s just bad policy.
Click to expand...
Guess BPE does not know what they are doing then! They only have the best warranty in the industry.
 
You must log in or register to reply here.
-

Back
Top