Im running a 250 chevy straight six, stock no upgrades beside intake and header...with a 500cfm Edlebrock thats been jetted down to about 430cfm "I believe". I'm running a fuel pressure regulator but I'm not sure what presuure I should run it at...I've played around with it but turn it too low and it gets fuel starved when under a load or I get on it, but to much and I'm fouling out plugs...INFO KNOWLEDGE REQUESTED PLEASE
CFM is the amount of air the carb flows, therefore jetting will not change the CFM. What you have done by changing the jets was to lean the carb out some. As far as fuel pressure you will need a guage and I believe 4-5 lbs. should be the range you want to be in. The carb is probably still to big, a 390 CFM Holley would be more than adequate. Good Luck!
What is the elevation where you are running the car? I've had really good results dropping .001 under stock jetting, for every 1000 feet in elevation, on both primary and secondary sides, running stock metering rods. Set your fuel pressure at 5 psi, and you should be good if you have no other operational problems with the carb. Good luck!
Thats good news Heres how I've jetted it, is it correct? I used the guide that comes with Eldebrock carbs, I ordered the jets and metering rods to lean it out 12% the most possible. Then moved the stock primaries to the secondaries after I replaced the primaries. Correct? Incorrect?
1403 500cfm had .086" Primaries .095" Secondaries .065" x .052" M-Rods I changed it to this .083" Primaries .086 Secondaries .067" x .055" M-Rods ?????????????
.083 in the primaries will probably work well, but would try it with stock metering rods first. I think .086 is probably going to run too lean, and .092 will be closer to correct. A lot of this still depends on your elevation, which you didn't state. You should probably also check your float levels while you've got the top off, changing jets.
I would agree if it was a full mechanical secondary carb, but Carter/Edelbrock secondary air valve carbs, will only supply what the engine demands on the secondaries, and the primaries will work fine with that motor. I will agree however that it is more carb than the motor can utilize.
FYI for future folks looking for this answer...I finally got the 500 edlebrock four barrel dialed in on my 250 STR-6 I ended up using .083" Primaries .092" Secondaries with the stock metering rods. I know this is still too much for the motor to take full advantage of but it runs good. I can almost floor it of the line have to hold back just a little, besides that seems to run correct though all ranges of rpms and such Just thought I'd put this out there for those looking for answer...this is what worked for me.
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