any experience with Quick Fuel 450 VS Slayer carb on 273 ?

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lilredridinghoo

lilredridinghoo

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Hi, it´s been a long time since my last activities here...

finally i got the little motor running again after sitting for 3 years ...

again 273 wanna hear your opinions ...

as it´s getting warmer and spring is now right around the corner i was able to do some short test rides... and i have to say the 4160 Holley 600 cfm Carb i use at the moment is not the best choice...(pulled from an 383 bigblock and served well on my tweeked 5,2 Magnum) it´s partly to lean and partly to rich... and i´m tired of playing around with jets and power valves .. and beeing still not satiesfied at the end...

long story cut short: i´m thinking about buying one of those 450cfm Quickfuel VS Slayer carbs.... heard a lot of good storys so far...but not really in relation to a small engine like 273cui.

therefore, are there any users having experience with this carbs...

from my understanding it´s basically a holley with adjustable air bleeds, easy secondary adjustment etc...
 
lilredridinghoo said:
Hi, it´s been a long time since my last activities here...

finally i got the little motor running again after sitting for 3 years ...

again 273 wanna hear your opinions ...

as it´s getting warmer and spring is now right around the corner i was able to do some short test rides... and i have to say the 4160 Holley 600 cfm Carb i use at the moment is not the best choice...(pulled from an 383 bigblock and served well on my tweeked 5,2 Magnum) it´s partly to lean and partly to rich... and i´m tired of playing around with jets and power valves .. and beeing still not satiesfied at the end...

long story cut short: i´m thinking about buying one of those 450cfm Quickfuel VS Slayer carbs.... heard a lot of good storys so far...but not really in relation to a small engine like 273cui.

therefore, are there any users having experience with this carbs...

from my understanding it´s basically a holley with adjustable air bleeds, easy secondary adjustment etc...
Click to expand...
Pretty much all of the newer carbs need to some calibration tweaking. This includes the many of the standard Holleys made in the 90s through today.
All of the brand new carbs really should be checked over for proper drilling and machining debris.

With few exceptions (some BLP blocks) the idle feed restriction in a poor location for hopped up engines. So even with the removable air bleeds, drilling and tapping is still needed.

273 with what? Stock intake, cam, compression?
 
Mattax said:
Pretty much all of the newer carbs need to some calibration tweaking. This includes the many of the standard Holleys made in the 90s through today.
All of the brand new carbs really should be checked over for proper drilling and machining debris.

With few exceptions (some BLP blocks) the idle feed restriction in a poor location for hopped up engines. So even with the removable air bleeds, drilling and tapping is still needed.

273 with what? Stock intake, cam, compression?
Click to expand...

thanks Mattax... i know there will be work still needed to get a carb work perfect...

273 .040over
318 Heads bowl blended, opened intake runners to 340size, bit of portwork, polished chambers and exhaust runners

cam is (as far as i know the only) custum made whiplash cam for a 273 from Hughes - produces about 12-14 HGin at idle
206° @.050” intake with .473” lift, 216° Exhaust with .495” lift. – 107° Lobe separation

intake is an Offenhauser 360° single plane

Stock converter, 904er with shift kit, 3,91 rear with 26inch tall tires

longetube headers unrestricted mufflers 2,5inch dual exhaust
 
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Seems like is is an engine you might be taking over 3000 rpm
With those engine specs, definately worth checking to make sure the idle feed restrictions are in the lower location. This way they stay submerged and restrict consistantly.
 
I agree. With that combo a 650 should work fine. I think the 450 might be a bit small.
 
A couple things

I've used quite qa few QF carbs and have never been disappointed. Often, not always, they have been real close on AF meter right out of the box with just a 4 corner idle screw adjustment.

I've never seen a smaller carb disappointed anyone street driving. While I've seen huge differences going from the carter to holley platform, the smaller carb tends to be fine on the street. At the strip, the larger carburetor has always won in my experience. I've seen more than one engine make 500+ HP on a 750 carb and seen over 400hp on a 500cfm 2 barrel. I wouldn't be concerned with it being too small.
 
Little red what have you been using to tune the carb you have on it now? Reading plugs ar a o2 sensor? Curious.
 
My only experience with 1850 Holley carb on the 273 was good, but got tired of constantly dorking with it. But my 273 was quite a bit hotter than yours, 284 duration solid lifter. I ended up with the OEM Carter about 500cfm, which was better, but the best was with a 750 Thermoquad off a 71 340. By then the 273 had J heads, 340 cam and intake. I'm thinking 450 cfm might be a bit small?
 
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