Could changing rods/jets help my pinging issue?
Thread Starter
Pro
Joined: Oct 2007
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From: Overland Park Kansas
Could changing rods/jets help my pinging issue?
Right now I have a 795cfm Edelbrock 1903 Q-Jet on my 383, and as stated in other threads I'm having massive pinging problems. I've tried plugs and retarding timing and everything else but it still pings.
It mainly pings when the car is lugging along with the torque converter locked up at really low (1000-2200) RPMs. I don't notice any real pinging at WOT.
Right now the carb is stock with 73 main jets and 50V rods. Any opinions on if changing the jets/rods could help the pinging, and if so, which sizes should I look at changing to?
Also, looking at http://www.edelbrock.com/automotive_...ss_q-jet.shtml it seems like for my model (M4M) the smallest rod they sell is .048. Could I use a rod from the 4MV model to make it even more rich on cruise?
Thanks
It mainly pings when the car is lugging along with the torque converter locked up at really low (1000-2200) RPMs. I don't notice any real pinging at WOT.
Right now the carb is stock with 73 main jets and 50V rods. Any opinions on if changing the jets/rods could help the pinging, and if so, which sizes should I look at changing to?
Also, looking at http://www.edelbrock.com/automotive_...ss_q-jet.shtml it seems like for my model (M4M) the smallest rod they sell is .048. Could I use a rod from the 4MV model to make it even more rich on cruise?
Thanks
Last edited by neuroclast; Jun 11, 2008 at 10:40 PM.
Race Director
Joined: Oct 2000
Posts: 15,053
Likes: 79
From: central FL, near the beach.
at 1000 it's on the idle circuit(adjust screws)
IMO u need EFI to run 1000-2200 correctly
Maybe lars has a solution.
many hot rods never see that range, except slowing down.
IMO u need EFI to run 1000-2200 correctly
Maybe lars has a solution.
many hot rods never see that range, except slowing down.
Last edited by Matt Gruber; Jun 12, 2008 at 07:27 AM.
Melting Slicks
Joined: Jun 2002
Posts: 2,844
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From: Orrtanna Pa.
Try pulling the vacuum advance off, and plug the hose. If the ping stops you need to work on the timing.
I had stalling issues with mine running too lean on the idle circuit, and have since fixed it with bigger idle feed restrictors, but never had any sort of pinging.
Usually pinging is caused by timing,running too hot,or just plain crappy gas.
I had stalling issues with mine running too lean on the idle circuit, and have since fixed it with bigger idle feed restrictors, but never had any sort of pinging.
Usually pinging is caused by timing,running too hot,or just plain crappy gas.
Thread Starter
Pro
Joined: Oct 2007
Posts: 587
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From: Overland Park Kansas
It doesn't run hot. Compression ratio is just over 11:1. EFI really isn't an option. With the vac advance pulled it still does it. Initial is already down to 10* if I go any lower my headers are going to be glowing
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Melting Slicks
Joined: Jun 2002
Posts: 2,844
Likes: 99
From: Orrtanna Pa.
That cam seems a bit small for 11:1 cr, but not much you can easily do now about it.
Does it ping early in the morning,like with a cool engine? Maybe a cooler theromstat would help.You might try some 1.60 rockers to fake the engine into thinking the cam's bigger. (By adding 2-3 degrees duration)
Does it ping early in the morning,like with a cool engine? Maybe a cooler theromstat would help.You might try some 1.60 rockers to fake the engine into thinking the cam's bigger. (By adding 2-3 degrees duration)
Team Owner
Joined: Apr 1999
Posts: 21,953
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From: Reno Nevada
2024 C3 of the Year Finalist- Modified
Years ago before I even heard the word dynamic compression ratio i built a 355 ci motor with iron heads and @ 10.7 compression. I used a Crane power max 272 cam.
I fought it for a couple of years with super ignitions that i played with the advance curve on distributer machines. I jetted it on a rear wheel dyno that i could use for hours on end with exhaust sniffers. I fully understand how to jet an edelbrock carb. I always carried moroso 104 octane booster.
What it came down to was just adding more cam duration. I went up to the power max 278 and detonation was a distant thought of what not to do.
Then on my first 383 build with flat tops and lots of good parts I used a 232/240 solid roller and it was right on the edge of detonation. So I went up in cam duration and was good to go
I fought it for a couple of years with super ignitions that i played with the advance curve on distributer machines. I jetted it on a rear wheel dyno that i could use for hours on end with exhaust sniffers. I fully understand how to jet an edelbrock carb. I always carried moroso 104 octane booster.
What it came down to was just adding more cam duration. I went up to the power max 278 and detonation was a distant thought of what not to do.
Then on my first 383 build with flat tops and lots of good parts I used a 232/240 solid roller and it was right on the edge of detonation. So I went up in cam duration and was good to go
Thread Starter
Pro
Joined: Oct 2007
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From: Overland Park Kansas
Well I guess I'm stuck with a cam change then. I've never done that before but I'm guessing it's going to be a big project. At least for a slightly bigger cam I shouldnt have to change springs or anything.
If I do go with a slightly bigger cam, how is my 2800 stall converter going to effect it? Will it just not be quite as fast under acceleration or what?
If I do go with a slightly bigger cam, how is my 2800 stall converter going to effect it? Will it just not be quite as fast under acceleration or what?
Team Owner
Joined: Aug 2006
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From: Columbia Missouri
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
The quench area is the space between the outside circumference of the piston head and the cylinder head. It is this area that causes the air and gas to be squeezed which creates a turbulence in the space between the piston head and cylinder head that assists in the mixing of the gas and air.
It's my understanding that if you get too thick of a gasket, the air and fuel doesn't mix properly, or efficiently, and you get less efficient combustion.
I think there would be more benefits from a cam swap, than a gasket change, and you still have to take the top end apart. At least with a cam change the heads can stay on the engine.
Thread Starter
Pro
Joined: Oct 2007
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From: Overland Park Kansas
The quench area is the space between the outside circumference of the piston head and the cylinder head. It is this area that causes the air and gas to be squeezed which creates a turbulence in the space between the piston head and cylinder head that assists in the mixing of the gas and air.
It's my understanding that if you get too thick of a gasket, the air and fuel doesn't mix properly, or efficiently, and you get less efficient combustion.
I think there would be more benefits from a cam swap, than a gasket change, and you still have to take the top end apart. At least with a cam change the heads can stay on the engine.
It's my understanding that if you get too thick of a gasket, the air and fuel doesn't mix properly, or efficiently, and you get less efficient combustion.
I think there would be more benefits from a cam swap, than a gasket change, and you still have to take the top end apart. At least with a cam change the heads can stay on the engine.
Team Owner
Joined: Aug 2006
Posts: 24,125
Likes: 15
From: Columbia Missouri
That's what I would assume too but without talking to the builder or the person who filled out that sheet we can only guess that's what he meant.