I found from doing a bunch of research, the guys over at Turbomustangs website are very helpful with homebrewed turbo stuff. They really do not care if you Ford powered or not. Most are true hardcore Hot Rodders and will help you out with blow-through or EFI problems. Once in a while they might bust on you for being a Chevy, Mopar, or Buick guy, but they will help and really put some effort into it. That's where I was directed to the website on the carb mods. With them, it's like that's the basic carb mods you need to do to start with. Then they can help you get it down to perfect once you get the basic modified carb work done.
QuickFuel 650 tuning This discussion started when I ran a thread about using a secondary power valve. It has turned into a tuning discussion. So I decided to move the discussion to here as it seemed more appropriate. Base info: 462 BBB, 9.25:1 CR, ported iron stage 1's, headers, appropriate fuel system, custom solid lifter cam 248/260 @.50 .590 lift 114*LSA, AL2 with boost retard. The supercharger is a Procharger D-1, intercooled. I see about 7PSI at 5000 rpm. Timing is set at 22* initial, 34* total, dial back 1 degree for each pound of boost. Starting Point: QuickFuel 650 Ban. I Have really been half donkey about the way I was working on the carb so read all the stuff Mark put out, set up a tuning log, got a book on Holleys and read that so I have enough info to be dangerous. Not a lot of choice because there is no one to take this thing too that knows more than the people here do (I keep looking. ) How many blow through big block Buick's are out there? Start of the year. PRIMARY IFR 35 IAB 70 PV 3.5 PVRC 76 JETS 70 HSAB 31 SECONDARY IFR 35 IAB 70 JETS 76 HSAB 28 I think it is a bit strange that the HSAB on the secondary is a 28 and on the primary a 31. Is that because the primary open 1st? I think I should just drop some 80's in the secondary for the WOT. I think the IFR need to be smaller and then adjust with air bleeds. At this point AFR's were all over the place. To fat on the bottom too lean on the top and thinking I needed to add a secondary power valve to richen the top. Seems strange because my memory said I did not have any problems with going lean last year. Rule one: put a log together and write it down. At this point the curb idle is not bad. I can use the idle mixture screws to get it to idle at about 13.0 but as soon as you start to drive it the AFR's go into the 11's and WOT is going to the 12.'s so I have to shut it down from WOT. Next change: Idle is getting pretty good. Latest setup: Initial 22* total 34* pulling 1* for each pound of boost. Primary side: IFR:33 IAB: 74 JET: 74 HSAB: 31 secondary: IFR: 33 IAB: 73 (do not have 74's and they don't seem to change anything anyway) Jet: 84 HSAB: 31 Idle rpm is now 950 and AFR's in the 14's still only turning the idle screws out 5/8th but gained inch of vacuum to solid 9 inches. In gear will drop to 750 and go a little lean then come back to high 13's low 14's Cruise is starting to flatten out stays in the mid 13's all the way up to 2000. Then starts to go fat. WOT is in the 10's so I can start pulling some jet out of it. Going to go back to 70 in the front and leave 84 in the secondaries. With the big PVRC that should be close to square. Notice the important rule broken here? Rule 2: change one thing at a time. I changed the IFR's, the air bleeds, and the main jets. Went back and reread Marks post. Smacked self in head. It seems that the IFR's have a bigger change on the cruise AFR's than anything. So dropped a set of .030's in and reset the idle mixture screws. Curb idle is still 950 RPM and AFR about 14. When I drop it into gear idle drops to 750 and the AFR goes really lean 16 to 17. Motor does not die and after 30 seconds settles back to 14.5. Drives nice just putting around. Still pig rich anything over 2000 rpm and in the 10's at WOT. Next change is taking the mains to 68 primaries and 78 secondaries. Now it is really starting to lean out. Seeing 14's and 15's all the way up to 2500 rpm. Next is the part throttle acceleration. That sucks. Running way lean, 14's. So need to watch the vacuum and see what is happening there. I have a 3.5 power valve in so that may need to go up a bit. I now have more vacuum so that would make sense. So next step is a drive and check that. Current setup: IFR: .030 IAB: 74 PV: 3.5 PVRC: 76 JET: 68 HSAB 31 secondaries IFR: .030 IAB: 74 JET: 80 HSAB 31 After driving it a couple of times seeing the following: Curb idle pulls a solid 9" vacuum and AFR's around 14. As soon as I start driving it the AFR's are really flat from 1100 to 2400 rpm's and stay in the 15 to 16 range on the AFR's. This is a bit lean but the car does not stumble or surge. Need another ride to keep better track of the vacuum. Can see where it would be really nice to have computerized data collection. Part throttle acceleration is very lean. Will just stay in the 15's. Need to get a better handle on the vacuum. My guess is that it is not opening the power valve. I think I have a stock 4.5 to try, so that will be the next step. July 3rd Changed the power valve to a 4.5. Changed the right front jet to a 64 and the front IFR's to 33's. Curb idle is usually around 14's (tends to jump around a bit when you drive it but it goes back to low 14's. Cruise is now fairly flat all the way up to 70 mph in the low to mid 14's. So I am making progress there and am close enough to think I can get the cruise right at 15's no problem. Will take the front IFR's to 31 and the left front jet to 66. Big problems: Part throttle acceleration (maxed but not into the secondaries) the power valve is not opening. AFR's go to the 15's. Will try the 6.5 and hope it does not open at idle in gear. WOT is still way fat 10.0. At this point the carb is set up like this: Primary IFR's: 33 change to 31 IAB's: 74 Primary jets: 64/68 change to 64/66 HSAB's: 31 Secondary IFR's: 30 IAB's: 73 Secondary Jets: 78's HSAB: 31 Don't think I can worry about the secondary jets until I get the Power Valve to come in on part throttle acceleration. The goal for that will be mid 12's AFR's. OK, changed the right front jet from 68 to 66 and went to a 6.5 powervalve. The good news is my steady state cruise is about as good as it can get. 14.7 to 15.2. The bad news is that accelerating on the primaries will kick the AFR's up to 17's. When I go to full throttle it will go to 10.0 then climb up to 10.3. My conclusion is that the powervalve is opening but only at full throttle. Wondering if I should take it for a drive with no boost and see what happens. Any ideas here will be appreciated.
Sounds like you're getting there. Don't forget that setting the idle circuit and mains lean will only work right if the PVCR comes in early enough to handle all moderate to heavy part throttle acceleration, and the pump shot covers any off idle and sudden throttle position increases with fuel. Think of the jets (including IFR) as sustaining steady cruise AFR, and the pump shot and PVCR handing additional fuel to cover transitions, and loaded AFR. 15-16 at higher cruise is fine if the car likes it, and doesn't run hot. You won't believe the improvement in mileage.
Exactly, the next step is to make sure the power valve is coming in at the right time. I put the 3.5 in when it was pulling 6" at curb idle. Now that it is 9" can start trying other power valves. Once I know that is correct can start playing with the PVRC. I now have a better collection of little brass parts to play with. As of this point I do not see how you can tune one of these carbs without working with the IFR's. It looks to me like the air bleeds are really the fine tune at the end of the process. Have to go slow right now because it is 90+ temps so that will show lean. Add another rule: Take more than one drive with the car before you make the next change. Be patient.
Yes, the stock IFR is no more likely to be perfect for every car than the stock jets. The air bleed should not necessarily be left for the end though because while it changes the shape of the delivery curve, it also changes the AFR across the board. If anything, change the bleed to change the curve, then change the jet to compensate for the curve change. Also, remember that jet changes tend to impact the bottom of the curve more, while bleeds affect the top more. The other thing is the emulsions, but that's getting to the final details. I got sick of power valve purchases and made "the ultimate power valve" toward the bottom of this page... http://www.burtonmachine.com/documentationtechnical/
Since this is my first real venture into serious carb tuning I really appreciate all the help. I think I am starting to make some good progress. Will post results as soon as it gets cool enough to change the PV. It's about 97 today so I am spending a lot of time supervising my golden retrievers fishing.
After more driving seeing this: Cruise AFR's in the hig 15's, curb idle around 14. It takes at least 30 seconds sitting at idle in gear for the curb idle to go to the 14's. Will idle at 16 to 17 for a while. Actually quite smooth so not going to worry about it. The 3.5 power valve will not kick in at 3.5. So going to work on that fine line between opening at idle in gear (vacuum about 5 inches) and kicking in on part throttle acceleration. Going to try this combination today. Change the power valve to 4.5 Change the primary IFR's to .033 and leave the rears at .030.
More on QuickFuel 650 July 8 PRIMARY: IFR: 033 IAB: 70 changed from 74 PV: 7.5 changed from 6.5 PVRC: .076 PUMP: 31 CC CAM: BROWN changed from pink JETS: 64/66 HSAB: .031 SECONDARY IFR: .030 IAB: 73 PUMP: 31 CC CAM: PINK JETS: 76/74 HSAB: 31 Idles at 13.5 AFR and the Vacuum is up to 10 inches. Cruise is flat at 14.7, WOT 11.7 @ 3 psi boost (dialed boost out to tune) Still lean on part throttle but in the low 15's instead of 17. Running much better. Can still go up on the power valve. Anyone need a 3.5, 4.5 or a 6.5 power valve. 1/2 price sale:laugh:
I really have to thank Mark. His directions for tuning are the best I have seen. If you spend hours reading (and I have) you will still not come up with what he has put together. If you want to tune a Holley follow his directions. Don't expect to hit it on the first try. Expect a lot of experimentation and frustration. I have watched a few dyno tune sessions and the "tuner" did nothing but change mains to get WOT close and pull the most HP. Great if you have a race car on a trailer. The real skill is to get a tune that works everywhere. Still have a way to go to be "perfect" but there is light at the end of the tunnel.
Trying something new. Tired of buying power valves. Took the spring from a 3.5 and 6.5 and will use them together. It seemed a lot stiffer than a 7.5 and it still idled OK. Will test when it cools off.
Glad to hear it is coming around! I know what you mean about "perfect". My car has been completely drivable for a long time, even when it had the bad intake gaskets that took forever to find. It is that tendency to want to get "that one little rich spot" tuned out, or that lean transition you can't feel but the wideband shows that becomes an illness of sorts!ou:
:laugh: We are indeed sick people :spank: Let it have some boost yesterday. Don't know how much because it hit so hard that I got a little scared. Frankenvalve showed that I need a bigger # valve and that the 76 PVRC's are too big. Said screw it and just ordered 3 QuickFuel valves 8.5. 9.5 and 10.5. Now have a pretty full set. Taking the PVRC's way down and jetting up a bit in the back.
Yeah, mark is GREAT! I am having him build my entire car and it will be nice to know he will be able to tune it right up! SO EXCITED for BOOST!!!!
More on QuickFuel 650 August 1st! Whole summer on carb tuning. Wish I could charge myself by the hour. Very happy with the carb right now. Here are the AFR's: curb idle high 13's, steady state cruise high 14's, part throttle acceleration high 15's, WOT 11.5. Steady state cruise is good to 2700 rpm! (80+) This is with a solid lifter cam 248/260 .590/.590 @114* Carb Data: Primary IFR .033 IAB 74 PVRC .063 PV 9.5 PUMP 31CC CAM BRN JETS 64/66 HSAB 31 Secondary IFR .031 IAB 73 PUMP 31 CAM PINK JETS 82/82 HSAB 31 Only change that I might try now is to try the 10.5 power valve and see if that will help the part throttle. The motor does not seem to mind the 15's on part throttle but could give a better throttle response.
Nice work! The lean transition into part throttle acceleration is exactly why I went with the custom power valve. Even the 10.5 wasn't snappy enough, but I was pulling 20-22" of vacuum on part throttle cruise. Your idle vacuum is MUCH lower, what is your warmed up level in town cruising vacuum? I have been amazed at how little jetting the mains need once that is sorted out though. I wish the 2 stage power valves flowed enough. They seem like the ultimate solution. Maybe I need to make a race version. I've just started the same thing all over again, but this time on a 1963 Galaxie 500 XL with the 3X2 carb setup. Thrice the fun! Lol!
Thanks, Cruising at about 12 inches of vacuum and a couple of pounds of boost in the hat. Will try the 10.5 PV next week and see what happens. What I really need now is a 3 inch pulley. Just did the math and found that I am at about 50% of what my blower can turn. With the 4 inch pulley on it now it spins the impeller at 35,000 rpm at 6000 on the motor. Blower is rated for 65,000.
More on QuickFuel 650 Tried the 10.5 power valve... still does not open for part throttle. Rain today so work on modifying a PV. Now trying to figure out why gas mileage is still terrible. How you can cruise at perfect AFR's (14.7) and still get 7 mpg is beyond me. Actually a lot of my cruising is in the 16's. I don't expect a lot but 10MPG seems like a reasonable expectation.
Re: More on QuickFuel 650 Doug It's really hard to get good gas mileage with 28 degrees of overlap on the camshaft. I'm interested in the reason for the camshaft choice. Are you using a crank trigger or a distributor to trigger the 6AL-2? If it was possible to get some vacuum advance during cruising, that would help with mileage. Paul
Re: More on QuickFuel 650 Camshaft is a custom setup from my engine builder. We talked about 2500 to 6000 rpm range with no more than 10 pounds of boost. It seemed like a lot to me but it is 114*LSA. Starting to wonder if I degreed it correctly (first time I ever installed a cam.) Ignition system could use an upgrade. Not using an Al-2, just a 6AL with boost retard box and Mallory distributor. Going to work on using the vac advance. Timing right now is 22* initial, 32* total pulling 1.5 degrees out per pound of boost. So right now WOT should be around 25* advanced. Also need to check on how fast the timing is coming in. I know it is a lot of cam. But I have a few friends with big Pontiac's running just as much cam and getting 12MPG and running pig rich. Also looking for any possible gas leaks. Thanks for the interest. Any ideas are welcome.
