Now that I've got the car running, I've got some performance tuning questions. The motor does not feel quite as strong as I think it should. It never really felt as strong as I think it should even before doing additional mods. The Items changed are: Comp 270H cam swapped for FMS X303 (.542 lift/286-224 duration) 351W heads swapped for AFR 185 Flat tappet lifter swapped for FMS retro-fit roller lifters Scorpion 1.6 rockers Others items: Edelbrock Airgap intake Mallory ignition MSD dist. Headman 1 5/8 headers 670 Holley carb stock fuel pump T-5 tranny 3.55 gears -It idles about 700 - 800. I can get it to idle lower but should I? When idling at 500-600, the car gets a bit... bouncy. The girlfriend likes it. lol -Vacuum reading is ~2.75 at idle. Isnt this pretty low? If the stock Power Valve (6.5) is still in there, should I change it to a 2.5? Actually, per the Holley tech page, I should be running a 1.5. What jets should I be running if I make this change? -Timing needs to be checked but from the previous setup should be at 36*. -Plugs gapped at .045 -I've been told I need a higher flow fuel pump. Suggestions? I was looking at this one, Summit pn HLY-12-289-11, but do I really need it? Original post on related upgrade issues -http://mmb.maverick.to/showthread.php?t=36754 As always... thanks for the assistance.
I don't have much for you but to say: You gotta have more fuel pump. You gotta 'super tune' your Holley. You gotta have the right power valve! That said, sometimes your car gets faster than you realize when you push the power up in the rpm band. You don't feel like it is faster because low end torque is softened. So the 'butt-meter' doesn't register it. I don't see where you mention what intake you are running. Also, what timing gear set? When you reassembled it, did you make sure the oil slinger, fuel pump eccentric, cam plate, and such were all correctly installed AND compatible with your new cam. Ford made several styles over the years. Cams and timing sets usually favor one type over others. I have also heard of folks accidentally getting the fuel pump lever arm on top of the eccentric, instead of under it properly.
Is that duration figure taken at 050 or is that net?? if its at 050 it explains the lousey vacuum reading.You may need to do some serious carb tuning.I would get the carb as good as you can w/o doing serious mods to it.Get your timing set up and put a good electric fuel pump on it.Adjust your mixture and try to get that vacuum up a bit.A vac signal that low is going to wreak havoc with the carbs Idle And transition fuel delivery circuits.Make sure you dont have a vacuum leak thats pulling the vacuum down.As far as idle is concerned you can back it off as much as you want as long as it doesnt sputter /stall or pop out the carb when you step on the gas.It will run very rich that low though.You should tune it for best idle/best vacuum as a baseline and go from there.Hope this helps you,Good luck.
Picked up my own vacuum gauge and am going to try to adjust the timing and idle first. (After rechecking for leaks) Read on Holley tech that you should adjust your idle mixture screws for the highest vacuum reading. Per the FMS tech line, I should be at 12" - 13" with this cam at idle. That being the case, the standard 65 power valve should be perfect. Suggested areas to look for problems were, valves having too much preload, vacuum leak or poorly adjusted carb. (perhaps all of the above) Why does everyone go through the expense of adding an electric fuel pump rather than just stepping up to a higher volume mechanical? I read through some of the other post regarding electric and its not just a matter of buying and installing the pump itself. You also have to buy a properly sized regulator with return line for it to run effectively. Pricing wise, this triples the cost of an equivalent volume mechanical setup. "Butt Meter" began to register last night. I am expecting the car to just rip the tires off from a slow roll. I dont have that kind of torque. It was mentioned in another site that this cam performs best at 3k and up. So I tried it. From second gear rolling down the highway, I layed on it. When it hit about 3300 I felt it open up. Speed increased so rapidly I just had to get out of it. (it was dark on a 2-lane road) Then in a more secluded area, dumped the clutch at 2500 and the 275's didnt stand a chance. Time to get to work. I knowtheres got to be more in there after getting this thing tuned.
What intake you running? You would probably run best with a single plane. ANY dual plane, I don't care which, starts to slack after 3k. Sure they keep going, but they are lazy at that point compared to even a very mild single plane. I didn't even think about maladjusted valves. That will do it! Also, I ran a Carter strip pump with great sucess. Electric pumps are not the be-all-end-all of fuel delivery. I have used them and found them VERY loud and often troublesome... compared to a good mechanical anyway.
idle speed I'd set it nice and low. Let the guys at the stop light see your cam! Besides, if your girlfriend likes it...isn't that why you bought a Maverick?
Ditto ratio411 on the single plane intake.It will allow the engine to pull in more unrestricted air at higher RPM.It will hurt off the line grunt in normal traffic use but,It will be much better for your combo than a dual plane.The off the line response wont be that bad anyhow,just a bit soft on the take off.Once you get it ironed out it will be a beast and a blast to drive.Enjoy!! the tuning is half the fun!!
