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I'm finishing up the 383 stroker build for my 76 and I'm thinking of swapping the Q-jet for a spread bore Holley carb. I would like to know exactly what is involved with this swap regarding the linkages and fuel inlet.
Not much for the Holley 4175 650 CFM vacuum secondary Qjet replacement carb:
Just the fuel feed....everything else hooks right up including the throttle linkage..............
Apparently photobucket wants money now to subscribe to their site for 3rd party viewing of photos so for the time being no photos available......jerks!
I had the double pumper version on mine for a while and I don't recall changing anything. Most quadrajet fans and traditional holley guys talk trash about them but they are really nice carburetors and perform very well. I like the double pumper better because vacuum carbs tend to be soggy and less crisp.
I recently replaced my quadrajet with a 6211 (really a 6212 with 6210 bowls).
The only real modification was to cut the throttle linkage bracket so that the mounting bolt on the drivers side was the only one used, and the alignment slot next to it.
Outside of that I run AN fittings. I can say this much, the fuel inlet is slightly forward of the qjet's, but in general its pretty close.
I will say this much... I like it. Im hoping you have an 800 spread bore as opposed to a 650.
I had the double pumper version on mine for a while and I don't recall changing anything. Most quadrajet fans and traditional holley guys talk trash about them but they are really nice carburetors and perform very well. I like the double pumper better because vacuum carbs tend to be soggy and less crisp.
I have had my 4175 since 1985 and really like it...the secondaries open at about 3,000 RPM when I need them and the power is very progressive with zero bog to 6,000 RPM...I use the lightest secondary spring. Does the double pumper version bog at all if you hit the throttle hard? I am running a 68 main jet but may need more like 70+.
Since you still want a spread-bore carb, the best and least expensive thing to do is to get your Q-Jet rebuilt [properly] and reuse it. I see no advantage to swapping the Q-Jet for a spreadbore Holley.
I had a Holley spreadbore (Model 4165, List 6210-3)on mine. Stock linkage and fuel line work fine but you will have to make a new choke rod.
But I had a fuel slosh problem with the Holley I was never able to resolve. The engine would die under hard braking. I went to a Lars rebuilt Quadrajet (pictured on Lars' test engine below) and have no regrets. More responsive and no more fuel slosh problem.
I have had my 4175 since 1985 and really like it...the secondaries open at about 3,000 RPM when I need them and the power is very progressive with zero bog to 6,000 RPM...I use the lightest secondary spring. Does the double pumper version bog at all if you hit the throttle hard? I am running a 68 main jet but may need more like 70+.
I have the Holley Street HP 650 DP with mech'l secondaries. No bog or hesitation from idle to 6200+ rpm. However, it took a bit of tuning to get it running properly especially with a Team G SP intake. My timing curve is 22 initial and 12 mechanical all in at 3000 rpm. 8 degrees vacuum advance which eliminated ping at cruise. Also, 68 primaries and a 0.040 squirter.
Apparently photobucket wants money now to subscribe to their site for 3rd party viewing of photos so for the time being no photos available......jerks!
...and not just a little bit of money. They want $500 for the "privilege" of linking your photos to a forum posting. They have blocked all my photo posts for being a gross violator of their "linking policy." Jerks.
carb. cable and bracket work just fine as is. so does the choke linkage.
my best advice is to ensure you use the the original style,
1/4" thick gasket for temperature isolation of the carb.
to prevent fuel from boiling in the carb.
Holley Spreadbore, original throttle linkage.
None. When you post or reply here there is a small yellow box just above where you type in your message with what looks like mountains at the bottom. It is for inserting images right off the photos on your computer and works really well.
None. When you post or reply here there is a small yellow box just above where you type in your message with what looks like mountains at the bottom. It is for inserting images right off the photos on your computer and works really well.
Yes I was aware of that option but unfortunately I cannot see the actual photos saved on my computer without opening each one to look at.
carb. cable and bracket work just fine as is. so does the choke linkage.
my best advice is to ensure you use the the original style,
1/4" thick gasket for temperature isolation of the carb.
to prevent fuel from boiling in the carb.
For me, the "hump" in the middle of the throttle bracket (that goes over the vacuum port for power brakes on quadrajet) wouldn't fit with the Holley, so it had to be cut. You'd never know by looking.
I am getting ready to rebuild my engine and have been thinking about using one of the throttle body fuel injection systems instead of the stock carb. Money for new carb could go to cost of the system. Has anyone been using these trying to improve the drive ability of the car?
07-08-2017, 11:09 PM
Quadrajet to Holley Swap
