i have a 383 build in a z me and my brother have been working on the past few months when about a week ago a pinging started it occurred on the passenger side. we have tried adjusting the timing but oddly when revved the timing would drop, i bought a distributor and coil witch fixed that but the ping is still there. it struggles to stay at idle and will kind of choke its self when driven. I believe the motor is too fresh for carbon build up, all the spark plugs look to be fine and the wires are all new as well. we have not drove the car much at all once we noticed the ping but it seems to be getting much worse. I am still new to the hot rod world and need help, anything suggested will be much appreciated.
We need much more information. Where's your timing at now, static and total, c.r., gears, cam specs, trans, etc.? Is it running hot? Any backfiring from the carb or exhaust? What color are the plugs? When is it sluggish, off idle, at speed, WOT?
Purchase this light/10X magnifier.... Longacre 50886 Spark Plug Viewer With Holder
Put the light and enough tools in the car to remove and replace the spark plugs. Find a not so well traveled road and run through the gears. Go to neutral in the transmission, chop the ignition and coast to a stop. Remove the spark plugs, keeping them in order of cylinder. Inspect them with your light/magnifier.
Looking at the porcelain insulator up inside the plug, look for tiny little black specks. This would be oil blown out from between the rings and the ring land as the motor detonated. If the detonation gets worse, you will also see tiny little silver beads melted onto the porcelain. This would be the pistons coming apart.
If you see neither black or silver specks on the insulators, the motor is not detonating to the point of hurting itself, but you need to get a hold of the tune before it does hurt itself.
A engine that is overheating will ping under load. That condition is preignition and appears as if the timing is over advancing. The engine should run between a minimum of 180 and a maximum of 200 degrees, winter and summer.
If it is detonation, your compression ratio is too high for the octane of the pump gasoline you are using.
im sorry it has taken this long to reply i posted this right before i went into work yesterday and have not been on since then.
my brother and i do not know much about the motor besides it has 70cc aluminum heads, flat top pistons, 383 bottom end, holly 750 ultra hp double pumper carb, victor jr. intake, the cam size/piston size and compression ratio is unknown. it has a th350 trans and around 4.10 gears.
its hard to describe the problem besides the pinging noise coming out the passenger side is getting worse and the timing doesn't effect it
i have put 93 octane in it every time but i think the person who we got the motor from used something higher because he used it for the strip only, where im trying to make it a street/ strip car. The person we got it from said it would run on 93 so i trusted his word.
on the highway cruising at about 55 the temp slowly grew hot to about 210-220ish and then staid there. it has seemed to be a little sluggish all around at acceleration. when it starts up after idleing for 3-5 mins it seems like it still wants to die once put in gear but down a street or two that goes away.
If it's pinging on one side, that sounds like, assuming it is detonation or preignition and not some other sound source, that it is a local problem with a cylinder not an overall tuning problem. This engine has a lot of good parts but they are not related to each other in a GM production sense. My first inclination is to think that one cylinder may be leaking air at an intake manifold to head joint. This is a fairly common problem where small mismatches occur with parts from different sources. Often this happens on the underside allowing it to pull from the valley. Another could be a defective or incorrect heat range spark plug.
Sluggish overall and cruising hot sounds like a lean mixture or the cam and/or ignition is retarded. Keep in mind that the ignition times to the crank independent of the cam’s position so each needs to be checked.
Have you given any thought to a partially restricted exhaust system. Just thought i,d go a different direction as every one else is going to timing, and fuel.
Some years ago i had a Chevvy with a 283, Chevvy Fuelie pistons and a Crower roller cam,with a 3 x2 intake and it ran real good at the track and on the street. It started to overheat and ping and i found the mufflers had collapsed inside, partially. this caused backpressure in the system and caused the engine to ping and overheat. Not saying this could be your problem but it,s worth looking in to. I hope this will help you and hope you find your problem. I know there a lot of knowledgeable rodders on this site that will do their best to help you.
we have not drove the car much at all once we noticed the ping but it seems to be getting much worse. I am still new to the hot rod world and need help, anything suggested will be much appreciated.
"Ruff idle, choking itself, wants to die, getting worse" >>> Is this a hydraulic FT cam going south? dread. Did you and your bro install the cam? what type and what are the specs.
Have you pulled the valve covers and looked for broken springs, or other issues? pulled or broken studs etc >>> cam issues >>> you can do a quick check of the valve lift, spin it over and have a look see for rockers that dont wanna dance.
We do not know the specs of the hydraulic cam and didn't not put it in. We have taken the valve cover off and made sure they all are rocking the right way. There wasn't any broken springs or anything that looked out of place.
Would a higher octane gas such as 103 or 110 possible help this problem ? If so would 100LL or Aviation gas work, or should I just stay away from that stuff
poor selection for street use.Airplane plugs get cleaned every 50 hours of flight time.I flew my plane about 65 hours with out cleaning and had 2 plugs foul on take off.
try it as a "test" only.
Well if available and you have deep pockets then that hi test fuel cant hurt but seems to me the better route would be to keep on trying to determine the root cause of the issue.
When you say that things are getting worse that to me suggests that there are deeper factors at play here.
If it is timing >>> then start with basics, determine true TDC, verify the timing marks and tab are accurate, set the timing down to 10 deg base BTDC at idle, rev it up to 4000 rpm to determine that the total advance is less than 30 deg BTDC, disconnect the vacuum advance if you have it. Try crusing it around under light load and if it still rattles then chances are you have something else other than "pinging" going on, it goes away then stay focused on the distributor curve and the ignition in general. As mentioned before in other posts make sure that the A/F ratio is correct, no intake port gasket leaks and that the carb is not too lean.
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