Beautiful day here in southern Alberta so I decided to do some carb tuning on the 71 olds 461 engine wit a new eddy brock 750 CFm

So I installed new plugs and took it for a nice run and the plugs are still Snow White.

Stock main jet. Meter rod. Spring
0.110. 075 x 047. Orange 5- in Hg

First change
0.110. 075 x. 037. Orange 5 - in Hg

Second change
0.113. 073. X. 042. Orange 5 - in Hg


So I have the kit for this carb and the 0.113 jet and rod combo was the biggest it had...... Took it for a run and not seeing a big change

Can someone explain which spring would I use with the second combo
Blue 3 in Hg
Yellow 4 in Hg
Orange 5 Hg
Plink. 7 in Hg
Silver 8 in Hg

 

No one here has ever done any tuning on a 750 edelbrock carb here.......all these members here and no one??? lol




Can someone shed some light on the theory of the springs.......did some searching and some recommended using the silver springs with my third rod and jet setup

 

If you tuneing for better part throttle performance start with primary jets with the leanest cruise rods . go on a flat road do about 45 to 60 MPH keep down sizing the jets down till you get a bucking feeling when the throttle is steady. now go back up on the rod richer till it gose away. if it dont go up a jet and start over . it might take a while to try but you will be close. it might take the next jet up and a richer rod . as for the spring once you have steady throttle. run the car at 45 and give a good squeese like your passing ,go up or down tiil you feel the best throttle responce most engines with good idle vacume 5 inches is way to low. now for the accerator pump just change the rod low hole it you dont have a heatation from a dead start it might be ok go up one more hole if it feels better. you just dont want a lag then go like hell. rich is useally lazy . . too much pump shot waste gas . sometimes the butt dyno cantt tell the diffrence it best to go leaner if no hestation or lag is noted.