Who is running a Quikfuel 450 on their Slant

-
cchrishefish

cchrishefish

Well-Known Member
Joined
Oct 22, 2009
Messages
768
Reaction score
153
Location
USA
I know a few members are running the Quikfuel Slayer 450 on their slant. I am trying to dial my slayer in. So if any members changed power valves or jets ETC. Please chime in so I can get this puppy running the best that I can. I have the Aussiespeed Hurricane with Clifford Shortys.
 
So here are a few of my symptoms, the carburetor required me to turn in the idle mixture screws almost all the way into the carb to get the highest vacuum reading. So I am only about one half turn out for the air fuel mixture screws. The car occassionaly idles a little too high even though I added slack to the throttle cable and turned the idle all the way down. It almost acts like it is returning to high idle but not as fast, so maybe my return spring is not heavy enough. I can get the idle to lower when I give the throttle a quick snap. It hesitates slightly when I put the pedal to the metal.
 
Check for vacuum leaks. Is the choke hooked up, if electric it will need power or you will have issues. I'm not familiar with the /6 but how is the carb mounted as in is it sitting on an adapter? You have a 4bbl manifold? I know the /6 Distributor gear is plastic, any change this is dancing on you making the idle erratic?
 
dano said:
Check for vacuum leaks. Is the choke hooked up, if electric it will need power or you will have issues. I'm not familiar with the /6 but how is the carb mounted as in is it sitting on an adapter? You have a 4bbl manifold? I know the /6 Distributor gear is plastic, any change this is dancing on you making the idle erratic?
Click to expand...
No adaptor, it is mounted to an Aussispeed intake. I suspect that the throttle cable is binding. This was my first time installing a Lokar style cable set, so my inexperience is probably the issue. The hesitation is probaly a tuning issue which will have to be determined. Maybe I need a different power valve or jet?
 
I think for anyone to suggest getting into the carb we'd need to know the build on your /6. As I understand the jets have nothing to do with the idle circuit.
 
dano said:
I think for anyone to suggest getting into the carb we'd need to know the build on your /6. As I understand the jets have nothing to do with the idle circuit.
Click to expand...
Pretty much a stock slant bore .030 over with a high performance ignition, Aussiespeed Hurricane intake, Clifford Shorty headers, and a custom 2.5 inch single high flowing exhaust with a thrush turbo muffler.
 
I had a similar problem with my 450 ( not a quickfuel & mech. secondary's ) I had to much timing in it. ended up pulling some out to be able to set the idle.
mine I was never able to get it to where I was happy with it. the mechanical secondary's were just to much for the slant. after thinking about it now, I could have just eliminated the seconday linkage and wired them shut and tuned it like that.

my build is similar, hurricane, clifford shorties, but with the block milled .120 and a cam and ported head with oversized valves.
 
Where is your initial timing set?
 
cchrishefish said:
So here are a few of my symptoms, the carburetor required me to turn in the idle mixture screws almost all the way into the carb to get the highest vacuum reading. So I am only about one half turn out for the air fuel mixture screws. The car occassionaly idles a little too high even though I added slack to the throttle cable and turned the idle all the way down. It almost acts like it is returning to high idle but not as fast, so maybe my return spring is not heavy enough. I can get the idle to lower when I give the throttle a quick snap. It hesitates slightly when I put the pedal to the metal.
Click to expand...
#1 move without question is to be 100% certain the fuel levels are set exactly where they belong, period. Nothing else will work correctly until You do, & the way carbs get handled by shippers destroys the settings they left the factory with, literally 8-9 times out of ten. Just had a QF on a SBC S-10, brandy new, & the front was above the site-glass, the rear far enough below I couldn't see it!
 
Oh, & check the fuel pressure, 6psi. on those max.................
 
vitamindart said:
I had a similar problem with my 450 ( not a quickfuel & mech. secondary's ) I had to much timing in it. ended up pulling some out to be able to set the idle.
mine I was never able to get it to where I was happy with it. the mechanical secondary's were just to much for the slant. after thinking about it now, I could have just eliminated the seconday linkage and wired them shut and tuned it like that.

my build is similar, hurricane, clifford shorties, but with the block milled .120 and a cam and ported head with oversized valves.
Click to expand...
I have the Slayer 450 CFM which has a easy adjustment to change when the secondary opens.
 
I am going to have my go to shop to install a new set of Lokar knock off cables. I am also going to see if an additional return spring may help with getting the throttle to return more smoothly. And, I will see if they can dial in my carb to where it is supposed to be.
 
I played with the float for about an hour, seems to be in the right position now. I do notice an improvement in performance now, but it still has a minor hesitation when I put the pedal to the metal. I put the vacuum gauge on again and I get the highest vacuum reading at about one half turn out. I am going to change out the spark plugs when my new spark plug tubes arrive from Australia. If I were a machinist I would make about a 100 or so for all of us slanters to use. My car has a baby oil drip coming from the number 6. Probably because someone at one time thought they should leave the washer on the plug.
 
cchrishefish said:
I am at 10 degress BTDC.
Click to expand...

That "might" be some of the issue. I have my stone stock 170 up around 12. Is yours completely stock? If not, it probably needs more. Mine loves the additional timing. I have it on the edge though, ONE more degree and it starts a little bit of a rough idle. lol
 
Last edited:
cchrishefish said:
I played with the float for about an hour, seems to be in the right position now. I do notice an improvement in performance now, but it still has a minor hesitation when I put the pedal to the metal. I put the vacuum gauge on again and I get the highest vacuum reading at about one half turn out. I am going to change out the spark plugs when my new spark plug tubes arrive from Australia. If I were a machinist I would make about a 100 or so for all of us slanters to use. My car has a baby oil drip coming from the number 6. Probably because someone at one time thought they should leave the washer on the plug.
Click to expand...
Accel pump adj. or change cam/squirter, if the timing/advance checks out,.........
 
RustyRatRod said:
That "might" be some of the issue. I have my stone stock 170 up around 12. Is yours completely stock? If not, it probably needs more. Mine loves the additional timing. I have it on the edge though, ONE more degree and it starts a little bit of a rough idle. lol
Click to expand...
I will give that a try when I get the secondaries adjusted, right now they are opening too early and bogging when I floor it, so yesterday I turned it back to the position it was in from the factory. I turned the secondary screw one turn out before paying attention to the floats. Right now, if I do not kick in the secondaries I do not get any hesitation, but when I kick them in I get a bogging sound. I will test it out this morning and may need to adjust it more.
 
cchrishefish said:
I will give that a try when I get the secondaries adjusted, right now they are opening too early and bogging when I floor it, so yesterday I turned it back to the position it was in from the factory. I turned the secondary screw one turn out before paying attention to the floats. Right now, if I do not kick in the secondaries I do not get any hesitation, but when I kick them in I get a bogging sound. I will test it out this morning and may need to adjust it more.
Click to expand...

It will probably need tighter than the factory setting. I would "just guess" those carburetors, like all four barrels, come set up for a small V8. When a vacuum secondary carburetor is set correctly, you should not be able to detect the secondary opening at all, but rather just feel brisk acceleration. A bogging sound and feeling normally indicates they are opening too soon.
 
I drove the car around yesterday and it seems to be running and idling quite well. On occasion, the tires squeal when it was not my intention. I have not bumped up the timing yet since I was forced to install new plank flooring in the family room, by the boss. I will bump it up this morning and see if the slant comes alive. I have added a few pictures comparing a Cole Muffler exhaust to my current high flow 2.5 inch exhaust. I hope you like the engine bay picture. I also needed to move the fuel filter closer to the engine fan to avoid heat from the headers.

104548725_3916469661758429_1426008724405548496_o.jpg


104100304_3916470581758337_1771463419474378539_o.jpg


101804846_3852945058110890_2997143103883706368_n.jpg
 
If the air/fuel mixture screws are out only a 1/2 turn you are rich on the idle circuit. So you can either decrease the size of the idle feed restricter or make the idle air bleed bigger.

If your engine is as stock as you say, then I doubt you have the throttle open too far at idle. You need to pull the carb off and flip it over to verify that the transfer slots are .030-.040 exposed. There are plenty of threads in the fuel systems forum here.

I would stop playing with the secondary opening until you get all the primary side issues cleaned up.

Set your power valve opening by CRUISE vacuum and NOT idle vacuum. For example, if you have 18 inches of cruise vacuum you need a 14.5 power valve. Sadly, there is no such thing. You may find a 12.5 power valve if you get lucky, but AFAIK, they haven’t made those in years, so a 10.5 is the best you can do.

Before anything else, add some initial timing to it. Just don’t get the total any higher that what it should be. You may have to recurve the distributor to get that correct.

If this carb is like all the rest of them (no reason to think it’s any different) then they are sent out dead rich everywhere. You just have to tune them.

I also forgot to mention the correct way to tune the primary side is to get the main jet as lean as possible without a lean surge. Then leave the primary main jet alone. If you are lean (or rich) at wide open throttle you need to change the size of the power valve channel restricters, which are the holes you find when you remove the power valve.

If the carb doesn’t have changeable jets in there, you can use 6-32 brass set screws in the holes and you just drill the brass with the hole size you need. Of course, you’ll need a tap and the correct drill, plus a pin vise and a set of 80-61 number drills. It’s easy when you get the hang of it.

Again, all this and more is covered in several threads over in the fuel systems forum. It’s worth looking at them if you really want to tune your carb for the best fuel efficiency and power.
 
yellow rose said:
If the air/fuel mixture screws are out only a 1/2 turn you are rich on the idle circuit. So you can either decrease the size of the idle feed restricter or make the idle air bleed bigger.

If your engine is as stock as you say, then I doubt you have the throttle open too far at idle. You need to pull the carb off and flip it over to verify that the transfer slots are .030-.040 exposed. There are plenty of threads in the fuel systems forum here.

I would stop playing with the secondary opening until you get all the primary side issues cleaned up.

Set your power valve opening by CRUISE vacuum and NOT idle vacuum. For example, if you have 18 inches of cruise vacuum you need a 14.5 power valve. Sadly, there is no such thing. You may find a 12.5 power valve if you get lucky, but AFAIK, they haven’t made those in years, so a 10.5 is the best you can do.

Before anything else, add some initial timing to it. Just don’t get the total any higher that what it should be. You may have to recurve the distributor to get that correct.

If this carb is like all the rest of them (no reason to think it’s any different) then they are sent out dead rich everywhere. You just have to tune them.

I also forgot to mention the correct way to tune the primary side is to get the main jet as lean as possible without a lean surge. Then leave the primary main jet alone. If you are lean (or rich) at wide open throttle you need to change the size of the power valve channel restricters, which are the holes you find when you remove the power valve.

If the carb doesn’t have changeable jets in there, you can use 6-32 brass set screws in the holes and you just drill the brass with the hole size you need. Of course, you’ll need a tap and the correct drill, plus a pin vise and a set of 80-61 number drills. It’s easy when you get the hang of it.

Again, all this and more is covered in several threads over in the fuel systems forum. It’s worth looking at them if you really want to tune your carb for the best fuel efficiency and power.
Click to expand...
I did see somone mention that the Holley power valves work in the Quickfuel carburetor, has anyone done this?
 
Here is my idle vacuum reading. I have confirmed that my throttle cable is binding a little bit. I believe I cut it too short. Again, this is my first Lokar cable install so inexperience is the issue here.


104445628_3925364980868897_2507338585704725291_o.jpg
 
16.5 cruising at 40mph and 55mph. 19 in drive while stopped, 21 in park.
 
You must log in or register to reply here.
-

Back
Top