DAN76

I know this has been discussed before.....

I've just swapped out my old 2 barrel rochester carb and stock intake for an Edelbrock Performer intake and 750cfm carb.

I've driven it about now for a few days so I could get used to the car and it's speed again and am pretty sur ethat the performance increase is about ZERO!!!

Has anyone else encountered this problem before?
I've heard from many that the Performer 750cfm is rubbish but surely it must significantly out perform my old 2g right????

csstrux

I have heard of issues like that as a result of "over carbing" the car. What condition is the cam in, have you done anything with the exhaust? An engine is essentially an air pump. If the parts are not balanced, they will not work efficiently together. If the cam is flat or worn you will not get any more air through the valves if you put a 900 cfm carb on the thing. Its kind of like stuffing a potato in a tailpipe. I would check jetting/ tuning first as it is least expensive, then check condition of cam, and get progressively deeper into it. Still learning myself here, but something in the back of my mind is tickling about looking at timing to. I will have to go look at the chassis manual now. GRR any how people who do this all the time will have better more acurate info to add soon enough.

Bluevista

I agree on the exhaust, does it have duals? I have a 2 barrel and put dual exhaust on and the difference is amazing, it feels like I took a potato out of the tailpipe. I'm staying with the 2 barrel, car runs like a bear and the quick acceleration from stops scares my wife when she drives it now, her leadfoot scares me.

DAN76

yeah she's already running duals.
Would a 425 BB High Compression motor be over carbed with a 750cfm?

I've been advised to try the 800cfm, or even a Holley. There's a cheap 650cfm Holley on ebay but don't want to go too low as essentially i'm trying to increase HP!

joe_padavano

Dan,

For your heavy full size, the 750 is not a bad choice. I'd start with the basics. Are you sure the secondaries are opening fully? I assume there's a lockout on the secondary air valve that is connected to the choke. Be sure it's adjusted properly to allow full opening. Similarly, verify that your throttle linkage allows all four throttle plates to fully open when you floor the pedal. I assume you've verified timing? Is fuel flow and pressure sufficient?

DAN76

Haven't touched the choke set up. It's the manual version so I just run it without choke. Am i supposed to block something off if i do this?

I also had to fashion a new throttle linkage so maybe that's not helping either.

Is it possible the trans isn't operating correctly? Perhaps i took something away when installing the new intake?

to be honest i'm only comparing to how it used to be so it's possible i may have done something wrong when installing the carb! but before i took it apart, the 2bl used to just manage to burn rubber from a standstill if i floored it in the S gear setting. Now it just pulls away with a furous engine roar but no screetch. I've tried it in the L gear setting and it seems to have more torque but still no tyre spinning

I'll get it tuned up down my local workshop and see how it performs from there. Time to hand the beast over!

ent72olds

I know you've posted before somewhere about this problem...like I've said before, IMO , it's the throttle linkage preventing the secondaries getting to WOT. I've done the same exact set-up on 2 cars recently, one on a 330 one on a 350. Had the same problem until I got the linkage figured out! One person needs to be in the car, one under the hood and floor it. See if the secondaries open ALL THE WAY! If he says he has it to the floor, grab the linkage and pull back more. If there is slack and the secondaries open more, viola! If not, then I am wrong......let me know. It worked for me

jaysun

Just throwing an idea out. Do you know how much fuel pressure are you running? 6.5 is the max for a edelbrock carb. To much fuel pressure, the carb will leak past the needle and seat and the car will run rich and be a dog.