Re: More on QuickFuel 650 Doug Just for a quick check on cam timing, remove the rocker arms and put a dial indicator on the end of #1 intake pushrod. If the engine balancer doesn't have all the timing marks then you will need to install a degree wheel. What a pain! The #1 intake lobe should be .050" lift at 14 degrees BTDC with that camshaft. Paul
Re: More on QuickFuel 650 Thanks Paul, Actually I am going to cheat and head over to Finishline and have Bobb check. Easier when you have all the tools.
Been away for a looong time. Thought I'd post up a couple of tips on the Edelbrock blow thru mod. First of all a big thanks to Justa350 for his posts on the subject and also some PM's. In a nutshell, I followed his mod. Soldered on nitrile floats, installed the marine accelerator pump seal, milled off the choke horn, etc. I don't remember the specifics on jetting. The car burned up and I didn't take notes. However, the biggest problem I had was getting rid of the lean hole under heavy part-throttle aceleration. I installed primary metering rods with a big step from light load to heavy load and went to the heaviest step-up spring (stepped up at the highest vacuum; 8" Hg I believe). This helped somewhat. I even experimented with putting various diameters of welding wire in the primary air bleeds. Again, this helped somewhat. Then I modded the carb so that the secondaries would come in sooner. Tuning the secondaries was always easy. A/F was always rock solid once they kicked in. This did the trick! I drilled a new hole on the tang where the control rod connects to the secondaries (pass. side), farther out from the center of rotation than the stock hole. Then JB welded a 1/16" shim on that ledge on the primary shaft that engages the secondary opening mechanism. Primaries came in sooner and reached WOT at the same time. The lean hole went from 17:1 to 15:1. I wanted to put in another 1/16" spacer and make them come in even sooner but the car bunred up and I never got the chance. The car was a little finicky on startup and did run a little rough until warmed up since there was no choke. One other tip that I think is good for all Edelbrock carbs, blow thru or N/A, is installing the marine accelerator pump. It has a much stiffer spring and it seems to provide crisper accelerations without bog. I would love to try it again someday and get those secondaries tuned just right. I know I could buy a CSU carb and it'd be right from the get-go but then I wouldn't be tinkering which is even more fun than driving in my book. As I was tinkering with my Edelbrock parts carb, I noticed that you don't have to do that crazy spacer/JB Weld thing. All you have to do is adjust the linkage arm that opens the secondaries. So in the end, you drill new holes in the secondary opening are that are up from the original (see photo. I drilled 2 new holes. The secondary linkage is in the middle hole). This changes the rate of secondary opening. Then you adjust the linkage (i.e., bend it shorter) so that the secondaries start opening earlier.
Hello, I'm only at the start of tuning my carb in order to run perfectly. Thanks for all the informations, I will apply them asap.... I run a SBB with a TA intake, and headers, MSD 6AL + BTM + coil and distributor. P1SC procharger. For instance I only changed the main jets but the result is not fine. I also need to buy a wideband AFR gauge in place of my low range gauge... David
Give us some more info on your setup. Need to know about cam and timing. What carb are you running? As I found out main jets are the last step in the process.
Oups, yes, I forgot to mention the carb.... It's a QFT SS-650-BAN, I also have an intercooler, Ron Davis dual fan radiator, Aeromotive fuel pump and regulator, fuel pressure is set at 6 psi ,... The engine block is (for instance ) bone stock so is the cam. I have a Scott Brown cam in a box for my second engine but it's under construction (slowly). I haven't noticed on paper my setup (my mistake)....but for now I run 72 and 78 main jets, timing is +-12 initial and 36 Total, but I have to look at what is inside the MSD distributor (second hand). I need to redo the initial setup of the carb blade (the square transfer slot exposure), to start from a good fondation. I haven't had too much time to work on it recently, weather is bad and I'm finishing to build my cal-look beetle (70's style) for the European Bug-In show next week end. But I have printed all the tuning tricks. So I will study them and try to applicate them..... I also have the opportunity to run the car on a dyno to tune it, but it's not cheap....
David, we can make that work. Do you have an AFR gauge yet? Also need vacuum gauge but I would guess you have a boost/vacuum gauge. My guess will be that you are pig rich at cruise and you can only turn the idle screws out 1/2 turn. Looking forward to seeing how this goes. I am going to be working on a Procharged 350 soon so will have a lot of data on the QF 650 BAN.
Hi Doug, I only have an Edelbrock monitor (http://www.summitracing.com/parts/edl-6593/overview/) but I will invest into a more serious tool with a wideband and digital! I have an Autometer boost/vacuum gauge but I d 'like to buy a vacuum gauge so I don't need to be inside the car to watch the numbers I was so rich that I couldn't stand next to the car, I leaned the jets but I'm not happy with the result, but I changed the settings and I think I have done worst than good on one point as I have a problem on the primaries round 2000-2400RPM (the engine seems to misfire). I just hope that I haven't a vacuum leak or another problem somewhere.... I will try to look at it this week-end otherwise it will be first week of july....I have looked at the way Mark explains how to tune and all the things you have already done , it will helpme a lot. I'm very fortunate to have this forum and you guys because overhere there is nobody to tune these cars :laugh: But I'm already surprised how well the car pulls when I hit the secondaries....I reached 12.5PSI on the recall gauge. By the way, any idea which spring combination and advance stop bushing must I use on the MSD distributor : http://www.msdignition.com/instructions/Products/Distributors/85551.pdf For instance, I have 2 (light) silver springs (2500RPM) and a silver bushing (25). Thanks David
David, as you may have read everyone I know thinks the QuickFuel BAN's come out of the box stupid rich. They do this to cover their behinds so they do not get sued for someone running so lean they blow their motor. You can get the wide open throttle to be OK with just the mains but the rest of the curve will still be rich. You will get to that when you start changing the idle feed restrictors. As I understand it you are running a stock motor which means you have a pretty small cam. So with your distributor I would run the black bushing that gives you 18 degrees of mechanical advance. So you could run 12 to 14 degrees of initial advance. With 18* of mechanical that will give you 32 to 34* of total advance. You have a BTM so have that at 1.5 degrees to start with. I would then start with stiffer springs so the advance is a little on the slow side to start with. Then you can go softer in stages to make the timing come in quicker. When you are doing boost go conservative and sneak up on the tune. Especially with timing. Eventually I plan on going to an MSD AL2 programable so I can lock out the distributor and use a computer to set the timing curve. I have not had a problem with power valves opening at WOT but part throttle opening is another story. Not a big problem as part throttle AFR's are 15 to 16 and as soon as the secondaries hit it goes to around 11:!. I know the turbo forums all have exotic power valve stuff going on but I have not needed to go there.
Doug, On the QFT card I received with my carb, it says that the Idle Air Bleed are 70 (I don't know what they mean), I presume that I have to change them to have a leaner mixture at idle ? I found them on car craft site, but can't locate them on the QFT website..... http://www.carcraft.com/techarticles/tuning_with_air_bleeds/photo_02.html When you set your advance timing, do you set your gearbox in Parking or in Drive ? at which RPM ? I now run 12 initial when in Drive with the silver 25 bushing. I will try what you told me and see what the changes are... Do you know at which RPM do the secondaries open ? Thanks David <iframe src="https://www.facebook.com/video/embed?video_id=10201242491121544" width="1280" height="720" frameborder="0"></iframe> :grin:
David, On timing, put the heavy springs in to start with and set the timing at 12* initial for now. The heavy springs make sure that your timing is dialed all the way back when you set initial. Also want to be conservative as we dial in the carb. You have mechanical secondaries so they open depending on the position of the linkage. If you look in the instructions for your carb there are 2 extra linkage rods that change the ratio of primary to secondary. I think the 60/40 is standard. So basically the first 60 percent of throttle travel is primaries and then the secondaries open. Now go ahead set the idle adjust screws. You did square off the primary idle transfer slot? :grin: Follow the directions that Mark posted to make your initial idle adjust. I hope you like to take your carb off the car and take it apart. It is going to be your new summer hobby. The idle air bleeds are just about worthless right now. I suspect that you can only turn your idle adjust screws out about 1/2 turn. Good luck and you are have more fun than me. My summer hobby is residing my house.
Yes I already removed the carb to square the primary idle transfer slot, and I didn't moved the idle screw since !! I just played with idle adjust screws ! I will try to follow Mark 's directions but I suffer a lumbago for 2 weeks, and still have one week at home where I can't work on my cars....then I return 1 week at work, then 2 weeks holidays in south of France....looks like the tuning will not be done soon Thanks for the advices David
