Originally Posted by FlyNavyP3
Originally Posted by Jmoney7269
Every engine I have ever built or helped friends upgrade we have put Holley 650 double pumpers on them and removed the manual choke. A properly tuned and matched carburetor to the engine shouldnt need any choke. Literally give it 2 little pumps and turn the key and it fires off in 2-5 seconds. The square bore holley carburetor is the best upgrade anyone can do for a engine. There is a reason why people who have had quadrajets then upgrade to double pumpers call them "quadrajunks".
My 434 has a 950 double pumper from pro systems with a 4 corner idle system and I have never heard of people adjusting air fuel mixture screws with a vacuum guage..... all air fuel adjustments should be made by "tuning by ear". Same thing we do for small engines that run phenomenal when I get done with them.
Quite a bit of misinformation here. Engines tuned currently do need a choke to assist with cold startup. Big difference between a street strip or race setup and a carb on a RV or truck.
The Q-jet is one of the very best carbs at accurately metering fuel across a wide RPM and load scale, it has WAY more fine adjustments available than a standard Holley carb, metering rods for extremely fine fuel control, lean cruise adjustments, in a word it's excellent.
So let's get this straight, since you've never heard of tuning idle mixture with a vacuum gauge, it's wrong, but doing it "by ear " is correct? Using vacuum is a perfectly acceptable way to tune idle mixture.
A well tuned Q-jet can out perform a Holley on a street driven vehicle in numerous ways, part throttle precise metering, outstanding throttle response due to the small primary bores, lean cruise adjustments for cruise mileage, increased load enrichment sensitivity over the Holley which just uses a fixed enrichment where the Q-jet is a curve as the metering rods withdraw, air door secondary on the Q-jet prevents lean bog when transitioning from primary to secondary circuits.
I'm not bashing the Holley here, I own multiple, but it's not fair nor is it accurate to say as a blanket statement that the Holley is ALWAYS an improvement over the Q-jet because it's just flat not true, they each have their place.
Misinformation? Lmao gimme a break.....
A holley 650 double pumper can do anything that a quadrajet can do, but better. The only reason in my eyes to put a vacum guage on a carburetor is if you're synchronizing two of them. In a majority of cases, a quadrajet is too lean, and therefore that is the reason it's so hard to start up and gets a smidge better fuel mileage. Modern carburetors can be purchased with all the customization that we used to have to send off and get done. A properly tuned 650 double pumper that has the right power valves, air bleeds adjusted, accelarator pumps adjusted, air fuel screws TUNED BY EAR If you know what you're doing, the carburetor wont need any choke! The first 350 I ever built we sent the carburetor off the CHUCK NUYTTEN and everything was matched to this engine and it's intended purpose, and not once did it ever need a choke from temperature ranges 20-110...... same old song and dance with any engine I have ever built or help a friend upgrade....... two small pumps, spin it over for 2-3 seconds and it fires off. And they/I dont have to sit for 15 minutes with the stupid thing on choke or even deal with the possibility of a choke failure. The reason most machines now days need chokes or enrichment circuits is because they don't have accelerator pumps to prime them for starting.
There was a comment made also about how most all that can do the miracle work on these carburetors have long since retired. There are still a few of us out there yet. I'm only 36 so lots years left yet...... and yes I would run a 650 double pumper holley any day on a rv or whatever else has a 350 to 454 engine.
P.S. tuning idlewith a vacum guage doesnt do a bit of good besides show how much vacum its pulling..... any mechanic worth his salt knows the only way to tune a idle air fuel mixture with a carburetor is by tuning it by ear, or using a stand alone oxygen sensor. In my experience, the only time I have ever needed to use a vacum guage was to calibrate throttle sensors to factory specs so that the ECU and fuel mapping was all on the same curve.....
Originally Posted by Jmoney7269
Every engine I have ever built or helped friends upgrade we have put Holley 650 double pumpers on them and removed the manual choke. A properly tuned and matched carburetor to the engine shouldnt need any choke. Literally give it 2 little pumps and turn the key and it fires off in 2-5 seconds. The square bore holley carburetor is the best upgrade anyone can do for a engine. There is a reason why people who have had quadrajets then upgrade to double pumpers call them "quadrajunks".
My 434 has a 950 double pumper from pro systems with a 4 corner idle system and I have never heard of people adjusting air fuel mixture screws with a vacuum guage..... all air fuel adjustments should be made by "tuning by ear". Same thing we do for small engines that run phenomenal when I get done with them.
Quite a bit of misinformation here. Engines tuned currently do need a choke to assist with cold startup. Big difference between a street strip or race setup and a carb on a RV or truck.
The Q-jet is one of the very best carbs at accurately metering fuel across a wide RPM and load scale, it has WAY more fine adjustments available than a standard Holley carb, metering rods for extremely fine fuel control, lean cruise adjustments, in a word it's excellent.
So let's get this straight, since you've never heard of tuning idle mixture with a vacuum gauge, it's wrong, but doing it "by ear " is correct? Using vacuum is a perfectly acceptable way to tune idle mixture.
A well tuned Q-jet can out perform a Holley on a street driven vehicle in numerous ways, part throttle precise metering, outstanding throttle response due to the small primary bores, lean cruise adjustments for cruise mileage, increased load enrichment sensitivity over the Holley which just uses a fixed enrichment where the Q-jet is a curve as the metering rods withdraw, air door secondary on the Q-jet prevents lean bog when transitioning from primary to secondary circuits.
I'm not bashing the Holley here, I own multiple, but it's not fair nor is it accurate to say as a blanket statement that the Holley is ALWAYS an improvement over the Q-jet because it's just flat not true, they each have their place.
Misinformation? Lmao gimme a break.....
A holley 650 double pumper can do anything that a quadrajet can do, but better. The only reason in my eyes to put a vacum guage on a carburetor is if you're synchronizing two of them. In a majority of cases, a quadrajet is too lean, and therefore that is the reason it's so hard to start up and gets a smidge better fuel mileage. Modern carburetors can be purchased with all the customization that we used to have to send off and get done. A properly tuned 650 double pumper that has the right power valves, air bleeds adjusted, accelarator pumps adjusted, air fuel screws TUNED BY EAR If you know what you're doing, the carburetor wont need any choke! The first 350 I ever built we sent the carburetor off the CHUCK NUYTTEN and everything was matched to this engine and it's intended purpose, and not once did it ever need a choke from temperature ranges 20-110...... same old song and dance with any engine I have ever built or help a friend upgrade....... two small pumps, spin it over for 2-3 seconds and it fires off. And they/I dont have to sit for 15 minutes with the stupid thing on choke or even deal with the possibility of a choke failure. The reason most machines now days need chokes or enrichment circuits is because they don't have accelerator pumps to prime them for starting.
There was a comment made also about how most all that can do the miracle work on these carburetors have long since retired. There are still a few of us out there yet. I'm only 36 so lots years left yet...... and yes I would run a 650 double pumper holley any day on a rv or whatever else has a 350 to 454 engine.
P.S. tuning idlewith a vacum guage doesnt do a bit of good besides show how much vacum its pulling..... any mechanic worth his salt knows the only way to tune a idle air fuel mixture with a carburetor is by tuning it by ear, or using a stand alone oxygen sensor. In my experience, the only time I have ever needed to use a vacum guage was to calibrate throttle sensors to factory specs so that the ECU and fuel mapping was all on the same curve.....
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