How to get more hp out of the 289

[steel1212]

Yeah, I agree with D.Hearne on the vacum secondary thing. I have a mechanical secondary 650 in the basement that I've never tried because my 670 street avenger with vacum secondaries has not let me down yet and I'm almost to the 12s.

 

[D.Hearne]

I had a 650 DP Holley on my "spare" 5.0 for my Ranger before I put the 331 in. This motor was pieced together from spare parts: ported E7's, F4TE roller (.445/.473 lift--256/266 degree duration with 1.7 roller rockers) 9.0 to 1 compression, stock E/F150 bottom end, Ford A321 intake. This motor made lots of vacuum and torque from idle to 5500 rpms (valve float) and with the 650, it did OK, but it wasn't till I bolted on a slightly modified 1850-600 cfm Holley that I saw the difference. With a "white" sec. spring, it would try to open the secondaries at idle, causing me fits to get the idle speed low enough. Had to change to a "purple" spring to fix this and get the idle down to 600 rpms. When you nailed the gas, you could "feel" the secondaries kick in about a second after you romped on it. And the difference in off idle response was noticeably better than the DP carb was. And you could also feel the difference when the secondaries came in as well.With a stock 2 bbl 289, even the smallest 600 DP would likely be too big to give good performance, especially with a stock geared Stang with an automatic.

 

[69Rcode_Mach1]

I also agree with D.Hearne and Steel on this one. Do not get a DP especially if you drive the car often. For an engine as mild as yours it will do nothing but hinder it. On top of that it is an automatic and a DP on an automatic is just asking for trouble, you will bog and stumble off the line so bad it won't even be worth it. DP's are harder to tune especially for an amateur which I am and I had a lot of trouble getting the thing to idle right when I first started it. Stang302V8 your carb must have had problems, I have always had good experience with vacuum secondaries and they can be tuned to give a good kick when need be. The only time I could justify a DP was on a manual tranny car, which planned extreme upgrades (not the ones in my sig, the parts I will be adding on), and I have yet to see if my justification means squat since I haven't even driven the car yet I may be overcarbed and have tuning issues too, you never know.