Mach 1 Club

Full Version: Eldebrock carb. tuning...
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I've really been enjoying driving my Mach 1 this spring. Under most circumstances it runs grest. Lots of power in the 3000-5000 power band. Pretty good out of the hole thanks to the 3.73 trac loc. My question is regarding carburation. Currently I'm running a Edlebrock 625 performer & performer intake. When I had the engine rebuilt I payed extra for balancing & blueprinting, I wanted to be able to push 6000 r.p.m. whenever needed. I have a carb. calibration kit with a variety of metering rods and springs. As is the car seems to lack enough fuel at above 5000 r.p.m.s. I'm not sure if I can improve performance with the calibration kit or if I really need a 750 c.f.m. carb.
I appreciate any input either way or any other ideas.
I am running a stock fuel pump and lines. HEI ing.
Thanks, Keith
SSig_help
Since it is an Eldebrock this sounds like the perfect question for JTS71 - he'll be along shortly.
Well thanks Steven. I can guarantee you need more CFM. Wether it be the carb or the manifold. A moderatelty built 351 Cleveland can easily take 750 to 800 CFM and if built to the hilt 1000+ CFM isn't out of the question. All metering rods and jets will do is richen or lean the mixture at various points in the RPM range. Which is meant to fine tune the carb to the engine. First make sure you not starving it for fuel correct size fuel lines flares not formed correctly, can partially block a fitting and cause this, also a restrictive fuel filter.You'll need a good fuel pump. A Carter mechanical fuel pump is more then sufficient. Some after market pumps may be inferior. If that all checks out. What Rpm range is the intake supposed to be good for? I believe it's a dual plane? Most dual planes are good till about 6500. It may be that it doesn't work well with the cam? I used an Edelbrock Torquer 351 single plane on my 71 Mach1 and it would consistently go past 8000 at will. Even with a 650 Carter AFB ( which is virtually the same as the Edelbrock) so I'm thinking your cam and manifold aren't working very well together??? One other thing make sure the timming is right, and the centrifigual advance is free and advancing as I 've seen that cause similar problems. if you HEI is a GM style the weights could very easily be hanging up under the rotor cap. If all else fails. You could look Edelbrock up on the computer and call their tech line. They may be able to shed some light on the cam, (you'll need the cam specs) and manifold working together. Keep us updated. We'll figure it out. Good luck JTS 71 Mach1