Hey all. I've got a Barry grant speed demon 575 carb 4bbl, with vac secondaries. I'm going to try to tune it for the first time so I need a little incite. If it's buring too lean, will the engine have certain characteristics of burning lean? burning rich? Is it tuned when the engine runs as smooth as its gunna be? Sounds like a dumb question I know. Is there anything important to know while tuning?

Right now when I drive it, it sort of sputters and I hear pops coming from the mufflers. Kinda like backfiring. It also stalls at lights when the rpm's are below 800 or so. I think it needs a tuning.

 

Acouple things go together when tuning.Timing..and Carb.Check your timing first to see where ur at then tune the carb then check the timing then adjust the idle speed screw..Typically u turn the idle mixture screw in until it starts to run worse then turn it back out until it smooths out.

 

I have a 66 with a rebuilt 289 auto, performer heads and manifold, performer plus cam and pertronix flame thrower and coil. My idle vacuum is 21fps. I had a ede 600 that I just could not get tunned to my satisfaction. I got the road demon 575 and installed it today. First a couple of notes. The hard fuel line that Jegs sent with it would not clear my heads so I set off to the local parts stores to get some fuel line. No one carried and the counter jockeys thought brake line would work. well after flaring the ends let me tell you that steel will not work. It leaks like a siv. I ended up at OSH and found 3/8 aluminum line and that worked great. I guess it's soft enough to conform to the fitting. Ok now about the tuning. I ended up setting the fuel floats about 3/4 high for best performance, the idle mixture screws were set using tach and vacuum gage. I set them to highest vacuum reading and "ear" for exhaust sound but mainly vacuum. It ended up about 3/4 to 1 full turn out. The choke (electric) seemed a little high for my taste, about 1500rpm, I like it around 1100-1200 for my engine but be forwarned that it is hard to get to the adjustment without removing the choke housing. Also, if you are using an electric choke you need to test the fit of your air cleaner before you install, the linkage will be a problem. I had to get a plastic spacer and cut some out to get it to clear the linkage and then install my ede cleaner on top of that. The bummer was that with the increase of 1inch for the spacer, my aluminum carb spacer put my cleaner into the hood, so it had to go. If I can modify the ede cleaner then maybe I can use my carb spacer again. I tried a Holly low profile but because it hangs "below" the top of the carb it hit the float covers. Anyway, I hope that helps. I like the carb alot, it idles better, revs quicker and is much smoother at the low end but has the power available if you get into it. note: this was a Road Demon though.

 

I forgot to mention that my timing is at 15 at idle right now but I will have to check the plugs to see if that is where it stays.
good luck and enjoy.

 

ok it's been along day, that should be road demon 525cfm.