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Topic Review (Newest First)
02-01-2013 08:23 AM
RWENUTS People seem to be hard of hearing lately.
Timing first!!
16-20 degrees initial.
Hook vac advance to ported or manifold. Your motor will let you know which it likes.
THen if you still have a stumble work on the carb.
It's been that way since the beginning of time.
Timing first, carb second!!!
02-01-2013 07:12 AM
cartoon14 no disagreement here, but we don't know what his vac numbers are we don't know the cam specs or any other info on engine condition. it stumbles off idle i acceleration which sounds more carb than timing so I offered a base line. if the engine vac is so low it wont run brakes, vac advance dist is probably not the best choice anyway.
01-31-2013 08:26 PM
cobalt327 Whether to use ported or manifold vacuum is a subject that has filled many threads. Suffice to say it depends on the combo and how much initial timing is being used. In cases where </= 12 degrees of initial timing is used (and the vacuum advance is limited to 10-12 degrees of added advance like is recommended for a performance ignition advance setup), manifold vacuum almost always works better than ported vacuum.

A cam that's barely able to supply enough vacuum to operate power brakes in a 350 sized engine is big enough to need timing in the area of 16-18 degrees as a starting point. When using a stock distributor this will usually mean the mechanical advance has to be limited to keep the total timing (initial plus mechanical, no vacuum added to this figure) from going higher than 36 degrees BTDC for non fast burn heads. Fast burn heads (Vortec, etc.) use 30-32 degrees BTDC as a starting point.
01-31-2013 07:58 PM
cartoon14 if it stumbles off idle and then accelerates try replacing the metering rod spring to a stiffer spring I use the plain steel as a base line. kit # is Edelbrock PN 1464. make sure the metering rods float in the bore freely they will get sticky over time (especially if the car sets up over long periods) and make you think something bad is going on. Timing 8-12 degrees advanced without vacuum advance hooked up. also vacuum advance should be plugged into carb above the throttle plate not to manifold vac
01-28-2013 06:33 AM
33Willys77 When setting the timing, get all the intial you can - without making hard starts (difficult to tell without knowing cam specs). Edelbrock carbs work much better with more intial timing. If you can get it to 14-16 intital, you will probably see a difference with the stumble. May also need more (dought it would be less) of a shot of gas (pump adjustment). Take others advice and get the timing set and read the manual - you will learn much more by reading the book than just playing with the carb.
01-28-2013 02:49 AM
Originally Posted by 65ragtop View Post
I have a Chevy 350, with a cam just big enough not to lose my power breaks (dont know exact specs), dual plane intake, 600 cfm Edelbrock carb w/elect choke (10 years old), elect ignition w/vaccum advance. Car has not been run much other than in my drive way, around neighvborhood, and a few times down a country road jumping on it a few times for a few blocks. Right now I have the timing advanced a bit to keep it from shutting off. When I jump on the gas pedel, it hesitates then kicks in and runs good. I'm being told it needs to be re jetted due to the large cam, one says the eccelorator pump might be bad, which will cause the hesitation. I heard on one blog that the 1406 Edelbrock 600 cfm w/elect choke is set up at manufacturer to get better gas mileage not performance like the 1405 (manual choke) version and that rejeting with 1405 specs did wonders for his car. Does anyone have any suggestions?
Timing first, then carb.

You can't safely just crank in a bunch of timing w/o knowing the total timing, else you can detonate the pistons/bearings out of the engine.

More on timing.
01-28-2013 01:19 AM
JeffB Look at the accelerator pump it is probably set it the center hole,try placing the link in either the top or bottom hole and road test it.Most of the time it will cure your bog issue.To do further tuning order an Edelbrock kit #1487.
01-27-2013 04:41 PM
Originally Posted by camaro355 View Post
timing at 8 degrees turn the air fuel mixture screws all the way in and back them out 2 1/4 turns
With his set up he needs 18-22 degrees initial, 10-12 in mechanical plus his vacuum all in by 3200rpm.
Then play with the carb.
01-27-2013 02:00 PM
camaro355 timing at 8 degrees turn the air fuel mixture screws all the way in and back them out 2 1/4 turns
01-27-2013 11:05 AM
Irelands child
Originally Posted by joe_padavano View Post
Assuming you have the timing correct and there are no ignition problems, you MIGHT want to go to the Edelbrock website and download the carb manual that tells you exactly how to tune these carbs. There's also a video.

Edelbrock Carb Owners Manual

Edelbrock tuning videos
Gee - maybe you ought to try read the preceding posts, i.e. the third one
01-27-2013 10:21 AM
joe_padavano Assuming you have the timing correct and there are no ignition problems, you MIGHT want to go to the Edelbrock website and download the carb manual that tells you exactly how to tune these carbs. There's also a video.

Edelbrock Carb Owners Manual

Edelbrock tuning videos
01-26-2013 02:56 PM
techinspector1 Whenever ignition timing is mentioned, I wonder if the poster is aware that the TDC mark on the inertia ring of the harmonic damper is capable of rotating on the elastomeric material that separates the inertia ring from the hub. If that has happened (very common), it will be impossible to set the ignition timing correctly. Please read through this tutorial.....
01-26-2013 02:56 PM
65ragtop I have the vacuum hooked up to the manifold vacuum port. Dont know the exact setting of the timing but I know it is advanced quite a bit. I'm going to play with the timing and get that dialed in like you guys recommend. After that I'll work on the carb. I appreciate your help guys. Will let yall know how it works out.
01-26-2013 02:29 PM
Irelands child After you get the timing set to spec, then you get to play with the carb. Yes, the 1406 is set up a bit leaner for mileage purposes but that's 'as shipped'. You will need a copy of the Edelbrock Performer carb owners manual and you will need to spend some time reading it as it can be confusing the first couple passes through. You will then need at least a 1487 calibration kit, but the 1479 kit has a better selection of choices (Carburetor Calibration Kits -

Owner's manual for the 1404 through the series of carbs: (it loads slowly)

This is all there is to them - and one of my 1405's with the electric choke add-on

01-26-2013 02:03 PM
RWENUTS Forget about the carb!!
Get the timing set right first.
What's your timing set at?
Ported or manifold vacuum to the distributor?
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