,QFT - Q - 650 Carb Question
09-02-2006, 02:22 PM
#1
Thread Starter
Join Date: Sep 2006
Posts: 2
,QFT - Q - 650 Carb Question
Hi all
I'm new at this, so I may ask some silly questions. I'm trying to find a site on the net that will teach you how to tune a carb. Either, I'm not looking in the right spots or I don't know what to ask the search engine, because I can't seem to find one.
My situation is this.... I recently purchased a 66 Mustang Coup for my son (Ok, it was for me, knowing that as soon as he goes to college next year I'll swap him my car for the Mustang)
The car was a 289 but it is now a 347 stroker with a 92 5.0 block. It has a 351 Ford Energizer Cam thats 570 lift, 240 duration and 112 lobe. It has Edelbrock RPM performer aluminum heads, Edelbrock Performer RPM AIR Gap Intake, Mallory Distributor, Hooker Super Competition Headers, all the good internal parts (honestly I can't recall the names but I know they were some of the best quality pistons, lifters, rollers, crank, etc we could find) we upgraded all the support pieces like pumps, radiator, balancer, transmission cooler, MSD ignition etc. we dropped 3.89 gears in the 9" rear.
Even before alot of the adds I had problems with the engine stalling when I gave it gas. The guys at the shop said it was because I had a older 650 double pumper on it and that it would be a good idea to upgrade the carb to one that could be adjusted better. They recommended a QFT 650.
So, they put that on at the same time they added eveyrthing else. I picked the car up on Friday and the first time I hit the brakes hard it died on me. But other than that it seemed to be doing fine. The following day when I took it for a drive I noticed that the idle -when in gear but stopped-, seemed excessively rough, I just attributed it to the new cam and told myself to get used to it. Then it continued to get worse, and the whole car would start rocking back and forth with each cycle. It seems like it would rock 2-3 inches on the left then roll and do the same thing on the right. Then the cycle seemed to last a little longer each time and then it died. I didn't smell excess gas or anything, and it started right back up when I turned the key.
The next time I came to a light and had to stop, it started doing it again, so I just put it in nuetral (it's a 3 speed auto by the way) and it seemed to be fine, it reved a little higher and didn't bog down.
I called the auto shop and they said that after a new engine build its normal for a engine to settle in and the it will need periodic adjustment. They suggested that I give the idle screw a quarter turn and see if that helps. I did it, and it seemed to work fine on the - in gear and stopped - idle level. However, when your parked the idle seems really high now and when you put it in gear to back up out of the garage, it spins the tires almost a full turn before the idle drops down. My old CJ's and Charger would drop the idle down if I gave the gas pedal a quick tap, but no matter what I do on the Mustang, it doesn't drop the idle lower - until I put it in gear.
To me that seems like it would be bad for the transmission (which is a rebuilt C4 with maybe 200 miles on it) and I think a 2600 or 2800 stall converter.
In addition, my son was saying when he turns the engine off, a few times he has had smoke fly out the air cleaner and the engine coughes and sputters when you tunr it off. I called the shop and they suggested to back the idle screw off a quarter turn and go to the passenger side of the carb and increase that side a quarter turn. no idea if that will work yet or not - to early to tell.
My questions are:
1. Are the different screws I can adjust on the carb for the idle speed when stopped and in park, and one for in gear and stopped?
2. Is there a website I can go to to learn how to do basic carb troubleshooting? Like carbsforsummies.com or something
3. Does anyone have any suggestions on how to reduce the parked idle speed, and increase the in gear - foot on the brake idle speed so that it doesn't die. Or. maybe its got nothing to do with idle speed its something else thats causing it do die when in gear - I have no idea.
Any suggetsions are welcomed.
Thanks
I'm new at this, so I may ask some silly questions. I'm trying to find a site on the net that will teach you how to tune a carb. Either, I'm not looking in the right spots or I don't know what to ask the search engine, because I can't seem to find one.
My situation is this.... I recently purchased a 66 Mustang Coup for my son (Ok, it was for me, knowing that as soon as he goes to college next year I'll swap him my car for the Mustang)
The car was a 289 but it is now a 347 stroker with a 92 5.0 block. It has a 351 Ford Energizer Cam thats 570 lift, 240 duration and 112 lobe. It has Edelbrock RPM performer aluminum heads, Edelbrock Performer RPM AIR Gap Intake, Mallory Distributor, Hooker Super Competition Headers, all the good internal parts (honestly I can't recall the names but I know they were some of the best quality pistons, lifters, rollers, crank, etc we could find) we upgraded all the support pieces like pumps, radiator, balancer, transmission cooler, MSD ignition etc. we dropped 3.89 gears in the 9" rear.
Even before alot of the adds I had problems with the engine stalling when I gave it gas. The guys at the shop said it was because I had a older 650 double pumper on it and that it would be a good idea to upgrade the carb to one that could be adjusted better. They recommended a QFT 650.
So, they put that on at the same time they added eveyrthing else. I picked the car up on Friday and the first time I hit the brakes hard it died on me. But other than that it seemed to be doing fine. The following day when I took it for a drive I noticed that the idle -when in gear but stopped-, seemed excessively rough, I just attributed it to the new cam and told myself to get used to it. Then it continued to get worse, and the whole car would start rocking back and forth with each cycle. It seems like it would rock 2-3 inches on the left then roll and do the same thing on the right. Then the cycle seemed to last a little longer each time and then it died. I didn't smell excess gas or anything, and it started right back up when I turned the key.
The next time I came to a light and had to stop, it started doing it again, so I just put it in nuetral (it's a 3 speed auto by the way) and it seemed to be fine, it reved a little higher and didn't bog down.
I called the auto shop and they said that after a new engine build its normal for a engine to settle in and the it will need periodic adjustment. They suggested that I give the idle screw a quarter turn and see if that helps. I did it, and it seemed to work fine on the - in gear and stopped - idle level. However, when your parked the idle seems really high now and when you put it in gear to back up out of the garage, it spins the tires almost a full turn before the idle drops down. My old CJ's and Charger would drop the idle down if I gave the gas pedal a quick tap, but no matter what I do on the Mustang, it doesn't drop the idle lower - until I put it in gear.
To me that seems like it would be bad for the transmission (which is a rebuilt C4 with maybe 200 miles on it) and I think a 2600 or 2800 stall converter.
In addition, my son was saying when he turns the engine off, a few times he has had smoke fly out the air cleaner and the engine coughes and sputters when you tunr it off. I called the shop and they suggested to back the idle screw off a quarter turn and go to the passenger side of the carb and increase that side a quarter turn. no idea if that will work yet or not - to early to tell.
My questions are:
1. Are the different screws I can adjust on the carb for the idle speed when stopped and in park, and one for in gear and stopped?
2. Is there a website I can go to to learn how to do basic carb troubleshooting? Like carbsforsummies.com or something
3. Does anyone have any suggestions on how to reduce the parked idle speed, and increase the in gear - foot on the brake idle speed so that it doesn't die. Or. maybe its got nothing to do with idle speed its something else thats causing it do die when in gear - I have no idea.
Any suggetsions are welcomed.
Thanks
09-02-2006, 03:06 PM
#2
5th Gear Member
Join Date: Feb 2004
Location:
Posts: 2,028
RE: ,QFT - Q - 650 Carb Question
This is the manufacturers home pagehttp://www.quickfueltechnology.com/ (I think) but it doesn't have any tuning instructions.I'll keep looking and see if I can find any general carb pages.
Here's one for Edelbrock.
http://www.edelbrock.com/automotive_...ers_manual.pdf
Here's one for Holley
http://www.holley.com/data/TechServi...ech%20Info.pdf
These won't have any specific data for your application but might be of some help.
Here's one for Edelbrock.
http://www.edelbrock.com/automotive_...ers_manual.pdf
Here's one for Holley
http://www.holley.com/data/TechServi...ech%20Info.pdf
These won't have any specific data for your application but might be of some help.
09-02-2006, 03:46 PM
#3
5th Gear Member
Join Date: Jun 2006
Location:
Posts: 4,089
RE: ,QFT - Q - 650 Carb Question
Sounds like your shop isn't real good at setting up a carb. Your old 650dp would have been just fine with some adjustments.
Your floats are definitely way off. Check the secondary floats. Note that the secondary bowl site level should be lower than the primary site level. If it's the other way around, swap the bowls. In any case, the secondaries are too high, which will stall the engine with hard braking.
Carbs require periodic adjustment no matter how old your engine is. Something/body has to compensate for weather changes, and you don't have a computer, so it's up to you.
HPBooks has quite a few manuals on carb's. Pick one up for a Holley (which is what the QFT looks to be based off of) and read away. After you get knowledgable that way, pick up a book on performance engines. Or, find a better shop...
If the torque converter is dropping the engine idle speed down that much from park, I doubt you have a big stall at all. Set the 'Park' idle speed down to about 1000 rpm or so. That should be plenty high for a 240 duration cam. A stall will drop that a couple hundred rpm, which may be on the verge of too slow, but it should still run fine when warmed up.
Your floats are definitely way off. Check the secondary floats. Note that the secondary bowl site level should be lower than the primary site level. If it's the other way around, swap the bowls. In any case, the secondaries are too high, which will stall the engine with hard braking.
Carbs require periodic adjustment no matter how old your engine is. Something/body has to compensate for weather changes, and you don't have a computer, so it's up to you.
HPBooks has quite a few manuals on carb's. Pick one up for a Holley (which is what the QFT looks to be based off of) and read away. After you get knowledgable that way, pick up a book on performance engines. Or, find a better shop...If the torque converter is dropping the engine idle speed down that much from park, I doubt you have a big stall at all. Set the 'Park' idle speed down to about 1000 rpm or so. That should be plenty high for a 240 duration cam. A stall will drop that a couple hundred rpm, which may be on the verge of too slow, but it should still run fine when warmed up.
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