What carb are you running in your 493?

[dadsbee]

Sucks and blows...

 

[Kern Dog]

A carb doesn't push anything. There's just more fuel available " on demand".

Uhhh, secondary squirters DO push something. What isn't needed or used ends up in the oil, the cylinder walls, the exhaust stream, the air we breathe...

 

[RemCharger]

Uhhh, secondary squirters DO push something. What isn't needed or used ends up in the oil, the cylinder walls, the exhaust stream, the air we breathe...

I see your angle. But the split second rear accel pump is calibrated to cover the lean hole just like the front. If there's excess fuel, someone did a baaaad toon- down

 

[BSB67]

Uhhh, secondary squirters DO push something. What isn't needed or used ends up in the oil, the cylinder walls, the exhaust stream, the air we breathe...

You know that they only squirt when you open the secondaries and they are never used/opened in normal driving. Never.

If you have fuel in your oil and are washing down cylinder walls it has nothing to do with it being a double pump carb and everything to do with poor tuning.

 

[koosh]

I have a Quick Fuel Q-850 on mine, runs great.

Mechanical or vacuum secondaries?

 

[koosh]

Engine builder told me he “preferred “ mechanical secondaries since vacuum cant be as “instant “ ?
And i still would like to know if i should be looking at a 750 rather than the 850?

 

[hunt2elk]

Mechanical or vacuum secondaries?

The Q-850 series I use is more of a race carb I quess. Mechanical secondaries and no choke horn or any provisions for ever adding a choke. I like them because everything in the carb is adjustable. I have used several of them on different street cars, always with good results, both 750 and 850 versions.

 

[RemCharger]

Mechanical or vacuum secondaries?

A Q is the performance mechanical secondary line of carbs

Engine builder told me he “preferred “ mechanical secondaries since vacuum cant be as “instant “ ?
And i still would like to know if i should be looking at a 750 rather than the 850?

Youre builder is right. And they put 850s on stock 440s for reference, you basically have a 500.

 

[33 IMP]

MY worthless opinion:
Throttle response will be better with a 750 than an 850
Top end power will be better with a 850 than a 750.
Mileage will be better with vacuum secondaries with either size.
For a hot rod or street strip car, a double pump 850 is called for.
If you are honest about wanting this to be a cruiser...... ? Put a cruiser carb on it.

 

[hunt2elk]

Personally, I prefer double pumpers. A guy can feel exactly when the secondaries are going to open, so if you want to drive for fuel economy, just stop short of opening up the back barrels. And for a 500" stroker, I would recommend a 850. Just tune the carb for your car and life will be good.

 

[koosh]

A Q is the performance mechanical secondary line of carbs

Youre builder is right. And they put 850s on stock 440s for reference, you basically have a 500.

Are you saying 750 not correct size for my 493? Remember, no racing

 

[koosh]

MY worthless opinion:
Throttle response will be better with a 750 than an 850
Top end power will be better with a 850 than a 750.
Mileage will be better with vacuum secondaries with either size.
For a hot rod or street strip car, a double pump 850 is called for.
If you are honest about wanting this to be a cruiser...... ? Put a cruiser carb on it.

So by your definition, is a 750 double pumper vacuum secondary appropriate?

 

[RemCharger]

It's either a VS, or a DP. But not both in one.

 

[koosh]

It's either a VS, or a DP. But not both in one.

Ahhh….ok thanks

 

[erickson]

my 750 DP. Hit 129 mph in my Daytona at the Talladega Speedway

 

[Kern Dog]

Are you saying 750 not correct size for my 493? Remember, no racing

I’m curious why you’d build a stroked big block just to cruise it.
I mean…. I cruise it too but I also peel out a lot and hammer it at WOT on occasion.

 

[dadsbee]

my 750 DP. Hit 129 mph in my Daytona at the Talladega Speedway

Was Johnny navigating on his little phone again???

 

[koosh]

I’m curious why you’d build a stroked big block just to cruise it.
I mean…. I cruise it too but I also peel out a lot and hammer it at WOT on occasion.

I didn’t build the motor

 

[Kern Dog]

That is splitting hairs, man. You have it now.
Summit racing has a decent calculator to determine the CFM needs for any engine. It uses cubic inches and intended max rpms as factors to choose a CFM rating.

 

[koosh]

That is splitting hairs, man. You have it now.
Summit racing has a decent calculator to determine the CFM needs for any engine. It uses cubic inches and intended max rpms as factors to choose a CFM rating.

Well…. I still have a full head of hair, so no issues there. Appreciate the Summit info. Just trying to get best bang for the buck while having a great running motor. It appears from most replies, some like 750, some 850, some mechanical, some vacuum. I guess ill have to close my eyes and make a pick! Lol