Rochester carb tuning/timing HELP!!

[Benjitis1]

Just installed a rebuilt vac advance dizzy installed with petronix. 99.9% sure its not 180 out.Installed new cap, rotor, plugs and wires. Hooked up a hose from dizzy vaccum to a barbed fitting i installed on firewall side of rochester carb that had been plugged by previous owner(has suction when slightly higher than idle.) Using timing light on the flywheel i can get the idle running pretty smooth, but i cant tell how many degrees before top dead center i am because there are no markings, just the needle and a white raised dot on flywheel. Anyways, after twisting the dizzy i can get the idle sounding great! But...as soon as i touch the gas, it sputters and wants to die. I move the dizzy in every damn position and when i touch the gas it f***** sputters, misfires, hiccups, etc!!! It didnt run that well when i bought it before replacing GM dizzy either. Im assuming its the carb and im wondering if ANYONE can give me some help or a link on how to adjust it. And I know at least one jackass will post in this thread to "get a stock carb" or "ditch the rochester." But now im broke and im trying to make the best of what ive got. So i dont need to hear it. Sorry this is so damn long.

 

[FineWynsFJ40]

I was there myself. Take a look at your points, that is what messed me up. I am not sure what petronix is, but if it has points you need to take a look at them. Also, check your fuel filters. Do you have the 2G carb? Also, make sure your choke is working properly, and the air jets aren't too high. I have a book I'll sell to ya for dirt cheap on Rochester carburetors, helped me when I had mine and for rebuilding it. Hope that helps!

Brian

 

[65swb45]

Ben, since BOTH barrels on the Rochester open simultaneously, vacuum drops off VERY QUICKLY. The carb is set up with a mechanical accelerator pump to supply a spray of gas during the lag time immediately off idle. Check for a strong, steady stream on the accelerator pump.

Finding out what your vacuum reading at idle is wouldn't hurt either.

Best

Mark A.

 

[Benjitis1]

FineWyns-Petronix replaces the points and its not the fuel filter since i just replaced it. I pm'ed you about the Rochester book.

Mark-I'll check for the strong steady stream on the accelerator pump. Im gonna get myself a vaccum guage today as well. Thanks.

Also, do you normally use the timing light on the flywheel ? There is a needle by the flywheel and the raised bump on the flywheel itself that supposedly is 7 BTDC. How am i supposed to tell how far 10 BTDC is without any kind of markings??

 

[Benjitis1]

Bought the guage, Vaccum at idle is 15 in.Hg. What that means, i do not know.

 

[40's rock]

Ive got one that was on my 76 from the po...couldn't figure out why it was running so rich...soaked it, rebuilt it...put on a weber and found out it wasnt the carb.... engine floated-lost compression...anyway, I have one I will sell you cheap.

 

[Benjitis1]

Well, sprayed some brake cleaner around the intake manifold and it seems ive got a leak. I'll come back to this thread after i get some new gaskets installed. Thanks for the help, i may need more later.

40's-rock- Thanks for the offer, but im gonna make this one work, after i replace the gaskets on the intake/exhaust/carb/etc.