It should be on a 104. That is the recommended intake centerline iirc.
Pinging B$@&%@rd 440!
- Thread starter mopower440
- Start date
-
mopower440
Well-Known Member
well, i do, but...i dont know the first thing about a holley and it would need to be gone through..I know i know....but i have never messed with one..Ive always been a thermoquad guy ..This was hogged out to be run on this particular combo by demonsizzler from moparts..But i agree, it could still be leaning out at that last 2% of the pedal.
mopower440
Well-Known Member
ok, i may be wrong then. i built the engine back in 2004 and i degreed the cam in at 4 degrees advanced from what its advertised at by recommendations from someone on moparts back then. I remember doing it to not lose any bottom end..which i dont know why now because it got plenty bottom end..
What ignition? Points? Vacuum advance? Retard ignition two degrees.
mopower440
Well-Known Member
electronic, ordered a fully curbed "to my engine build' distributor from halifax shop on moparts as he is well known for his distributors. It did help most of it but this last bit im talking about.
Reduce the air valve opening by 0.100". Try this first, very simple 5 min job. It does two things: richens the mixture & changes the mixture distribution. Make sure the air valve spring is adjusted to 2 - 2.5 turns, NOT the factory setting. The Holley intake is a single plane, often need richer jetting.
Also make sure it has 0.143" sec jets, but only if above fails to fix the problem.
Also make sure it has 0.143" sec jets, but only if above fails to fix the problem.
Kendog 170
Let the boy go !
Thicker head gasket?
jos51700
Green Bearing thread connoisseur
Aluminum conducts heat better, so they're less prone to ping. They usually raise the compression in aluminum heads to compensate for that, actually.
As far as your combo, have you done a plug chop to see if it ACTUALLY running lean? You're kinda guessing and throwing **** at it instead of being systematic. "I'll get the coldest plugs I can get" instead of maybe two steps to see if it's better.
So to be clear, whether you're stopped, or 120 mph, if you go wot, it pings, but if you go 98%, it doesn't?
Have you verified that it actually goes WOT when the pedal is floored? Like, checked to see if the plates are going all the way open? You might be just getting into the mains which are way lean but the carb isn't opening completely.
mopower440
Well-Known Member
yes, it indeed is opening. Its just that last little bit of opening that gets it..Im going to try adjusting the stop on the secondary air door.
An O2 sensor might be helpful. Weld a bung in each side so you can move the sensor to check both sides. The sensor is a good tuning aid and can be moved to other vehicles if necessary.
You could take the car to a chassis dyno to have the air fuel ratio checked where the problem occurs. If you do go to a chassis dyno shop have some options available to alter the air fuel ratio or the timing. A sharp dyno tuner might recognize the problem and have a solution.
You could take the car to a chassis dyno to have the air fuel ratio checked where the problem occurs. If you do go to a chassis dyno shop have some options available to alter the air fuel ratio or the timing. A sharp dyno tuner might recognize the problem and have a solution.
I had that issue and installed smaller air bleeds for the secondaries to richen it up on the big end . It was and easy test without disassembling the carb and worked. . I was running 12.8-1 with race fuel through mufflers. Something you could try if you have replaceable bleeds as the first picture. You can remove the fixed bleeds and install changeable style easy with the carb off. This lets you fine tune easily when at the track.
mgoblue9798
Well-Known Member
Have you pulled the plugs to look at them? Do you have any pics to post of them?
Also, not all detonation is audible. In other words it may be happening more but you can only hear it the last little bit of throttle opening.
Also, not all detonation is audible. In other words it may be happening more but you can only hear it the last little bit of throttle opening.
You don’t have a compression issue. You have a tuning issue.
That should run EASILY on 91. Probably less.
You have a horrible plug location. You have an even worse selection of spark plugs with those heads.
Slow the curve down through the middle.
You may need to go up in jet some to cover it up.
And I’d raise your coolant temperature to 180. You don’t have enough cylinder pressure to run the engine that cold.
You may be running into detonation because the engine is too cold and the fuel isn’t vaporized.
No, most likely not. Aluminium dissipates heat faster and it will help.
mopower440
Well-Known Member
UPDATE: Went out this morning and Tweaked the secondary air door by bending the tab that limits the opening. Didnt tweak it much but man did it ever help!! I think i only heard it ping a few times and the few times it did it, it didnt keep doing it.Bfore it was quite loud when it would do it. I drove it around quite a bit and even did low rpm stomps in 3rd gear and it was silent! NOW, The only thing different from the other day is that its about 25 degrees cooler today. 45 today and was 70 the other day, but as far as i always remember it always did regardless before..
Seems like your using your secondary air door like a choke blade to richen up the air fuel ratio.
That's exactly how it's designed.
I haven’t seen it mentioned had you tried making adjustments on the accelerator pump cam. You said at 1/8th throttle to me that’s about when the accelerator pump kicks in no? To compensate the transition. Could be an octane issue but to me it sounds more of an a/f ratio problem. If every where else is not pinging. Just richen that spot up a bit and see. That’s the cheapest and easy try.
Thermoquad.
AGH it appears reading is fundamental and the turkey brain isn’t helping.
I can completely relate.
It would be interesting to see what the air/fuel ratio curve is. Especially just before detonation.
This is the beauty of the TQ: so many sec adjustments & tweaks that can be done.
- as above, amount of air door opening
- air door spring tension
- air door starting point
- bending straight the forward facing lip on the air door as per the Competition Series
- changing the WOT angle of the sec t/blades
- changing the air valve dashpot. There are at least two models with different springs which change the release rate.
- different size hole in the dashpot to alter release rate
-
- as above, amount of air door opening
- air door spring tension
- air door starting point
- bending straight the forward facing lip on the air door as per the Competition Series
- changing the WOT angle of the sec t/blades
- changing the air valve dashpot. There are at least two models with different springs which change the release rate.
- different size hole in the dashpot to alter release rate
-
-
Similar threads
