331 pinging at 4krpm

Modular2v · Jan 27, 2006

well i think the carb is WAY to fat for the setup.....331 with stock heads/cam..with a holley 750dp and longtubes...(open headers right now) when i hold the motor and 4k rpms i hear a pinging out of the headers....the timind is 10+ running 91 octane......i wouldnt think the compression is high enough to ping running the stock heads and flat top probes but i could be wrong Anyone have an idea of what i should do? Befor 4krpms all is well. For all i know it could be something as simple as fouled plugs (havent had time to check them)

joel5.0 · Jan 27, 2006

Modular2v said:
well i think the carb is WAY to fat for the setup.....331 with stock heads/cam..with a holley 750dp and longtubes...(open headers right now) when i hold the motor and 4k rpms i hear a pinging out of the headers....the timind is 10+ running 91 octane......i wouldnt think the compression is high enough to ping running the stock heads and flat top probes but i could be wrong Anyone have an idea of what i should do? Befor 4krpms all is well. For all i know it could be something as simple as fouled plugs (havent had time to check them)

What distributor setup are you using?...need to check total timing @4k RPM to see how high it is going.... anything above 38° could cause the pinging problem,..... if you're using a vacuum advanced Dspark setup, check it w/vacuum line disconnected. LUK

Modular2v · Jan 27, 2006

joel5.0 said:
What distributor setup are you using?...need to check total timing @4k RPM to see how high it is going.... anything above 38° could cause the pinging problem,..... if you're using a vacuum advanced Dspark setup, check it w/vacuum line disconnected. LUK

funny u said that because i just got off the phone with my buddy that builds motors and he called me a dumbass for not checking it with the vaccum line disconnected....that will be the first thing i do when i get home....i set the timing with the vacuum advance connected so im guessing it is really advanced right now

Modular2v · Jan 27, 2006

can anyone give me an idea of what i should jet the carb at and set the timing at with a 150 shot?

jrichker · Jan 27, 2006

Modular2v said:
can anyone give me an idea of what i should jet the carb at and set the timing at with a 150 shot?

What happened to "Carbs are easier to tune and you don't have to mess with all that electrical stuff"?

Modular2v · Jan 28, 2006

jrichker said:
What happened to "Carbs are easier to tune and you don't have to mess with all that electrical stuff"?

your right it would be much easier to buy 200$ injectors, convert to maf, take the fuel rails off, put the new injectors on, reattach fuel rail and then spend 200-350$ getting a maf to match the injectors

jrichker · Jan 28, 2006

DMAN302 · Jan 28, 2006

FIGHT! FIGHT!...ok you two schoolyard, 3pm don't be late.

Michael Yount · Jan 28, 2006

2valve - get access to a wide band O2 sensor -- use that data to help you optimize timing and jetting...

Modular2v · Jan 28, 2006

Michael Yount said:
2valve - get access to a wide band O2 sensor -- use that data to help you optimize timing and jetting...

arent the widebands like 500$?

jrichker · Jan 28, 2006

Modular2v said:
arent the widebands like 500$?

Still cheaper than and valves and pistons when they break...

04sleeper · Jan 28, 2006

jrichker said:
Still cheaper than and valves and pistons when they break...

True. True.

Modular2v, the only way to get all you can out of your combo is to tune it.

Good Luck.

Michael Yount · Jan 28, 2006

richker/sleeper beat me to it -- keep driving that thing with a pinging problem. When that block splits right down the middle and takes out your stroker kit with it -- $500 will have seemed downright cheap.

bluevenom867 · Jan 28, 2006

This may be of some use:

http://www.holley.com/data/TechService/Technical/Carburetor Tech Info.pdf

Check and set your timing again,with the vac off.

And of course,try a little more octane to be safe.

Modular2v · Jan 28, 2006

well i pulled the plugs this morning and the plugs are BLACK!!!! it is running way too rich

Michael Yount · Jan 28, 2006

If it's pinging AND rich - then it sounds like you have a significant timing or quench issue. Long term detonation can be VERY destructive - best to get it fixed sooner rather than later.

It would probably like 12-14 initial with the cast iron heads, and around 34 total. Ideally, you'd want to do away with the vacuum advance and recurve the dizzy for about 20 degrees of mechanical advance all in by about 2500-3000 rpm.

Modular2v · Jan 28, 2006

Michael Yount said:
If it's pinging AND rich - then it sounds like you have a significant timing or quench issue. Long term detonation can be VERY destructive - best to get it fixed sooner rather than later.

It would probably like 12-14 initial with the cast iron heads, and around 34 total. Ideally, you'd want to do away with the vacuum advance and recurve the dizzy for about 20 degrees of mechanical advance all in by about 2500-3000 rpm.

that is what i set it at......the pinging issue is gone....NONE AT ALL! it is just running so rich, time to change the jets out

Michael Yount · Jan 28, 2006

Keep in mind -- mixture and potential for detonation go hand in hand -- if it's not pinging at that timing and it's rich, when you lean it out, it may start pinging again. The richer the mixture the less likely it is to detonate. The leaner - the more likely -- all else equal.

Unless you're changing to other components in the future, a 600 or 650 cfm carb is plenty for your combo. That 750 won't help peak power and will hurt bottom end.

Modular2v · Jan 28, 2006

Michael Yount said:
Keep in mind -- mixture and potential for detonation go hand in hand -- if it's not pinging at that timing and it's rich, when you lean it out, it may start pinging again. The richer the mixture the less likely it is to detonate. The leaner - the more likely -- all else equal.

Unless you're changing to other components in the future, a 600 or 650 cfm carb is plenty for your combo. That 750 won't help peak power and will hurt bottom end.

i bought the 750 because AFRs and a trick flow stage 3 cam are going in soon, i also have a NOS sniper system just waiting to be hooked up

joel5.0 · Jan 28, 2006

Modular2v said:
that is what i set it at......the pinging issue is gone....NONE AT ALL! it is just running so rich, time to change the jets out

Have you tried adjusting the mixture screws...checking the floats level?...you might want to take a look at this article. LUK

331 pinging at 4krpm

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