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Old 05-10-2013, 02:24 AM
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Edelbrock advice?

Is there any way an Edelbrock carb can cause intermittent pinging? My stroked 351W has pinged on and off for some time. I've had the distributor apart (MSD billet), tried running with vacuum plugged, retarded the timing right back to 8* with a total of 26* at 2500, and even changed the distributor (to Mallory electronic) with no change. It seems fine, but then it'll start really pinging under acceleration for no apparent reason. This can happen halfway into a tank of gas so there's no changes there.
I'm wondering if something's sticking in the carb to produce a lean mixture? Maybe low fuel pressure - Holley mechanical pump - would these produce pinging?
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Old 05-10-2013, 04:45 AM
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Maybe.
-Float level too low
I would look here as well
- plugged fuel filter
- too small/restrictive fuel filter
- restrictive fuel line (too small)
- weak fuel pump
- spark plugs wrong heat range
- a sharp edge of steel glowing and pre igniting fuel: spark plug, valve, combustion chamber edge, edge of head gasket, which leads me to the next
- leaky/blown head gasket
- vacuum leak (air leak) intake gasket, carb base gasket, vacuum line
- valve hanging open/weak or broken valve spring or inner spring
- cross firing spark plug wires
And one I just corrected on my '31 w/SB Ford
- headers contacting motor mount light enough to sound like a ping that eventually became a thunk as the motor mounts settled a bit more.
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Old 05-10-2013, 07:21 AM
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What cam specs do you have and what compression ratio? What grade fuel are you using? What advance curve do you have in the distributor (springs, bushing). To get this to run good, you should have as much intial advance you can give the motor. Total advance will probably end up around 34-36ish. What do your plugs look like?
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Old 05-10-2013, 10:42 AM
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Cam is Lunati Voodoo hydraulic roller, 221/229 @ 0.50, 112LSA. CR is 9.5:1. I use 97 superunleaded (UK), and MSD billet replacement dist was set at 32 all in at 2,500 with idle timing of 14, but to try to cure the pinging I've backed it off to 10* at idle with 28* all in, using the two strongest springs in the pack and the black bushing. I take it out to test, and it's fine, I can't make it ping whatever I do. The next day I'll start to climb a hill, or just give it some gas, and it'll ping like mad. Nothing's changed, same tankful of gas. I don't see how distributor timing can give intermittent problems, hence the question regarding the carb.
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Old 05-10-2013, 02:33 PM
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PINGING IS DETONATION. IT IS THE SAME AS SWINGING A BFH DOWN ONTO THE PISTON CROWN OVER AND OVER. SOONER OR LATER, SOMETHING WILL HAVE TO GIVE.
Reading this tutorial may help you understand why detonation occurs in motors not built with a tight squish. I have no idea of course, how you built your motor, but just want you to know that a tight squish of 0.035" to 0.045" will do wonders for allowing your motor to operate on pump gas with zero detonation.
Piston Head Clearance Guide - Tech Article - Chevy High Performance Magazine
A fellow shouldn't have to be dinkin' with the ignition timing to prevent detonation in a motor. He should build it right in the first place and be able to use all available ignition timing advance to make a powerful, clean burning motor.

Last edited by techinspector1; 05-10-2013 at 02:41 PM.
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Old 05-10-2013, 03:38 PM
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OK, but I'm hoping the engine was built with some kind of technical expertise because it's a Ford Racing crate motor. I know that may not be a guarantee, but I'm ever hopeful!

edit - also, as noted above, it's an intermittent problem, which makes me think it's not down to design. But, as ever, I'm no pro, so I respect all opinions.

Last edited by rsk289; 05-10-2013 at 03:53 PM.
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Old 05-10-2013, 04:33 PM
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Sticky or inconsistant power piston action/metering rods sticking down ( lean when should be up (power)
bent metering rod.

sticking inconsistant mech advance curve. I find the light tension springs that all a in at 2600 rpm to be too light and inconsistant.
better to use more initial say 18 and less mech advance travel say 14-16 deg and a slightly slower advance curve peaking at 3000-3200 rpm much more consistant. usually one light and one medium adv spring.
Verify timing returns to base at idle every time.


Vacuum advance is way to aggressive.. Adjust the rate tamer and limit the max possible amount to 12deg tops.
Carb WOT power jetting is just a bit too lean.. Increase secondary jet size one step and test.
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