full throttle pinging....., wondering...???? |
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full throttle pinging....., wondering...???? |
crash914 |
Oct 4 2005, 06:28 PM
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#1
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its a mystery to me Group: Members Posts: 1,827 Joined: 17-March 03 From: Marriottsville, MD Member No.: 434 Region Association: MidAtlantic Region |
Ok, When ever I go full throttle, I get a lot of pinging....
in first or second, I can full throttle, but have to shift fast to the quick revs. under part throttle, I can spin up to 6500+ with no pinging or problems. I just can't floor it. seems odd to me. my afr is down around 11:1 at full throttle, so I am running plenty rich. I am running 93 octane, might have to add some xylene. I am wondering if my throttle bodies are too large. I don't know if my air fuel meter can pick it up that quick. I really notice it when I am in 5th gear and am pulling from around 2500 to 6500. I do have a spare set of heads that I can get cut... all right here is the specs...103 by 80. .125inch barrel shims gives me around .1" clearance and around 9.7 to 1. megasquirted with twin weber throttle bodies and large injectors... herb |
Jake Raby |
Oct 4 2005, 06:36 PM
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#2
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Engine Surgeon Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
Whats your deck height??? if it's .100 thats a lot of the issues, you don't have very good squish and its throwing off the efficiency. I use NO MORE than .060 deck under any circumstance.
It sounds like a bit of misconfiguration. If you need less than 26 degrees of advance to stop the pinging you can bet that you have a misconfiguration, tjhats a tell tale sign that something is wrong.. large T/Bs or carbs increase the ability for the engine to go lean, even if you are reading rich AFR, especially at peak torque. STOP driving the engine if it's pinging as you are destroying the rod bearings and weakening the combustion chambers every time it happens. Pinging will kill the engine FAST. 9.7:1 is pretty healthy on pump gas, the .100 deck coupled with that is probably the culprit. 9.7 wityh tight deck is a much better combination as the added squish boosts efficiency and increases the detonation threshold quite a bit. My 3 Liter runs 10:1 with .035 deck and won't ping no matter what you do... |
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