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CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
I've got an issue with fluctuation in fuel pressure when ignition is in the on position to when the motor is turned over idiling. Here's a quick breakdown of my setup. Mild 355 oldschool camel hump heads, lunati's voodoo cam, weiand intake topped with an edelbrock 1405 600cfm carburetor. Fuel is delivered to the motor through and electric fuel pump.
Recently, motor sat for a few months causing the carb to gunk up and require a rebuild. Prior to the rebuild the motor was being feed steady 6.5 fuel pressure according to the gauge on the carburetor. Now it's reading 6.5 with fuel pump priming ignition on then once the motor is turned over its pinging at 7.5 close to 8. Noticeably the motor is running richer and I changed no parts on the rebuild excluding gaskets. What could cause this increase in fuel pressure? What can be done to fix this issue? Was considering a regulator. Any thoughts?
Yes only because I removed all parts to clean the carburetor. I did as follows in the carb rebuild instructions and used a 7/16 drill bit to measure float level. Would incorrect float levels cause change in pressure levels? Any recommendations on which regulator works best?
Float position can change the mixture ratio, but it won't affect fuel pressure.
If your electric pump is the type that has built-in pressure regulation, it probably doesn't need a return, so the "regular", $25(ish) Holley dead-head pressure regulator would be fine.
OK so I purchased the fuel pressure regulator recommended.
One remedial question I have is, on the regulator there are two "out" ports on both sides and an "in" port at the bottom, how do I run this on my setup? As mentioned I am using a 600 cfm edelbrock carburetor fed by an electronic fuel pump.
I have never used a regulator so don't haze me lol.
Any pics of setups using this type of regulator is appreciated.
OK seems simple, I went out and bought two 3/8"NPT fuel fittings to adapt the regulator to the pump and carb. What are you guys using to plug the side not being used?
OK seems simple, I went out and bought two 3/8"NPT fuel fittings to adapt the regulator to the pump and carb. What are you guys using to plug the side not being used?
3/8 NPT plug. I got mine at autozone but they also have them at lowes or home depot
5 to 5.25 psi on all of my edelbrock carb'ed engine. 5.5 psi is the true max pressure for the edelbrock carbs. Any abobe that and the pressure pushes the needles out of the seats.
Edelbrock says keep it under 6.5. The edelbrock pump is regulated at 6psi and will work without a regulator. Keep it between 3.5 and 6.5 and you should be good to go.
Edelbrock says keep it under 6.5. The edelbrock pump is regulated at 6psi and will work without a regulator. Keep it between 3.5 and 6.5 and you should be good to go.
Edelbrock is WRONG. and even their pump that says works w/o regulator will push the needles out and cause flooding.
I have used and rebuild 100's of the webber/carter/edelbrock (All the same basic carb design) carbs over the years. I used my 1st one 19 years ago when I was 15 on a GM diesel 6-71 converted to gas blower on a 327 engine in a vega for 1/8 mile drag racing at my local track.
Have modded these carbs for blow through use, tested and improved upon the carbs and with out question I can assure you, Edelbrock is wrong, yet again.
5.5 psi is the max pressure the std. needle and seat can hold at. The off road spring loaded needles can handle alittle high pressure.
For years Edelbrock even had the wrong float settings listed in the owners manual. I will have to dig the old manual out from around '98 or so but it had a larger gap setting listed. I contacted Edelbrock about that goof up and I guess the looked and listened, cause the next manual I seen was in 2000 and it had the correct 7/16" at rest, 15/16" to 1" drop specs listed.
06-21-2015, 01:05 PM
