Ok, here goes.
I need to fine tune my carb and I don't want to play with it forever so I would like to do it right the first time...
I have been reading up on how to set the idle mixture screws and how to tune and test the primary circuits on the carb but I need more information...
I have a Stock 289 with an Edelbrock performer RPM intake and Edelbrock 600 cfm carb, Duel exhaust, Mallory electronic ignition.

The problem I am having is once the car gets up to operating temp it pings at light and mild acceleration, but if I get in to the throttle a bit then it goes away.... and I have ruled out ignition, new distributor, coil, wires, and plugs, also set the timing at stock 6BTDC without the vacuum advance hooked up, and have played with it from there.... ruled out overheating as the thermostat is about 6 months old and I took it out and tested it (worked fine) and checked temp of upper radiator hose when the engine was at operating temp (180 deg) so the only thing left is fuel.... usually I run regular and the one tank that I ran premium it lessened the amount it pinged but didn't get rid of it.... So my assumption is that the primary circuit is lean and the secondary circuit is rich enough that when I get in to the throttle it evens out the lean of the primaries..... so if anyone has a technical article as to how to test and tune the carburetor properly that would be amazing (going to a mechanic is out of the question because I need to learn this stuff if I am ever going to be a good mechanic my self)

Thanks, Brian

 

Oh, I am off to work so when I get back in 9ish hours I expect 20 different answers and 5 or 6 different approaches to the problem.... but if that's asking to much then whatever you guys got will be good

Thanks

 

Google is your best friend.
http://www.fordmuscle.com/archives/2...ockCarburetor/

 

Pinging is usually timing related. Is the advance in your dizzy working properly? Is it adjustable?

 

Yeah, I have to agree, but he wanted to make sure his carb was tuned properly. Remember he said it smooths out when the secondaries open. I have had edelbrock carbs on various engines, and I simply don't like them. They are difficult to dial in. If 93 octane pump gas is not good enough, and screwing around with the timing is producing no results, then idle it up to no less than 850 rpm and go pedal to metal 24-7.

 

so either.....

A) get the secondaries to kick in sooner (can this be done on the edelbrocks?)
B) tighter spring in the dizzy advance so it doesnt get so much timing so soon (thats a crappy fix even if it did work)
C) retard the timing a little bit (which is also crappy cause hes already at 6.... i'd rather be at 8 or even 10 maybe)

am i missing something or does edelbrocks just suck?

 

If it's pinging that quickly with that little timing, my bet's on the dizzy being plugged into the manifold vacuum instead of ported vacuum. Disconnecting the vacuum advance (and plugging the port on the carb of course) will tell quickly if it's the vacuum or not.

Ultra lean can cause something similar to pinging, and will cause your engine to run on the hot side.

When fine tuning a carb, there is no 'quick' route. It's all about trial and error over time.

 

Your trouble is not the carb..it is the ignition. When the carb opens-up the power valve is open and vacum is low so you do not get the cylinder charging you get at small throttle openings. Your stock cam is a low lift short duration/overlap cam that fill the cylinders very well at part throttle. Crower ran huge cams in engines as a test to prove you could run 12.5 static compressions ratios on pump gas due to very poor volummmetric efficency at part throttle. You need to take the distributor to a shop with a machine to set it to factory or try using a timing light and timing tape on the harmonic balancer to see what is happening. Until you do this you are as thty say "piccing in the wind".

 

Instead of bashing the equipment that KBunny and many other people on this board (including myself) have, I offer a more productive solution... In order to properly tune the carb, you first need to have the timing set correctly and make sure the timing advance is working properly. Colorado_Mustang had a good thought with the distributor being plugged into the wrong vacuum port. This would cause the timing to be advanced all the time instead of high speeds/loads. Check my picture for reference. The distributor also has weights/springs in it to mechanically advance timing... it could be that you threw a weight or something. Use a timing light and rev the engine from idle to about 1500 - 2000 RPM and you should see the timing mark move. The link that Soaring posted to Ford Muscle is good stuff, but that's the next step that you haven't gotten to yet. Good luck, keep us posted.


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I didn't know we were bashing equipment. I thought we were exchaning ideas about what works best with our classics.