Hey there, I have a 1971 Chev El-Camino running a 468ci Big Block motor in it.It has oval port heads and alot of other 'Go Fast' Goodies in her.She is running a Holly manual electric fuel pump and I find that she starts missing and farting a bit and that the sparkplugs are wet with fuel.Feeding the ports is a Mid-Rise Holly Inlet Manifold but sitting on top of this manifold is a Quadrajet carb.Distributor is a Mechanical Advance only unit as well.My question is.What Carb would be best suited to this Big Block Setup and what kind of Jetting would give this engine maximum response.! Motor was dynoed at 550hp. Your ideas and imput would be much appreciated. RegardsPieter At present she is running Open Hooker Super-Comp Headers.
The 780 I've got listed is on my engine at the moment, 461cu" with similar set up as yours, has 70 front jets and 72in the rear at the mo and the engine loves it.
extrayda,
Jun 25, 11:33am
Does the fuel pump need / have a return & regulator! (re-reading your post I'm not sure if it is mechanical or electric!).I'm sure I read somewhere that quadrajets don't like high fuel pressure! What coil / ignition system do you have!My 383 used to fuel up the plugs (esp the front two for some reason) when I had a mechanical mallory dual point and high output coil.Swapped to a MSD6A and MSD 5551 (I think) dizzy and all of those problems just went away.Was running a tall single plane intake and 750 DP carb. Only 420Hp, so not as grunty as yours :-)
corvette3,
Jun 25, 8:02pm
Sorry about the confusion.It is a Holly Ellectric fuel pump that is manually turned on on the dashboard.I used to run MSD on my Big Block Mustang at the time .My Tractor Puller is running MSD 6AL and it is a fine ignition system.I think that the carb is basically a mismatched fit to the motor
corvette3,
Jun 25, 8:10pm
Thank you for the link
petermcg,
Jun 25, 10:13pm
The quadrajet carb is to small and this will result in a high vacuum signal, and the quad carb might not like that,, fuel pressure could be to high for the carb, but dont change the pump change the carb,also what do you run on top of the carb you did not tell us that.
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