Ok I drove my 65 chevelle to Reno for hot August nights and it ran decent but before I had swapped the hei distributor out as the shop I took it too banged on the distributor and it would die. So I changed it out to a msd distributor I had from my old motor. I set timing to 29 total timing no vacuum. I deciding to get on it and it pinged again. So I took it to another shop that I know they checkedthentiming it was 37 tt and as the mechanic friend went to loosen the the bolt for the hold down and the idle changed and we stopped he did not even loosen the bolt and the tt went to 27 degrees. Wtf this car is really Christine. I could really use some advice before I yank this motor to warranty this thing out. .
Timing issue pinging is driving me nuts help???
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Running 91 octane? News Flash: in 1973, REGULAR GRADE GASOLINE, on the average, was 91-93 octane...!
I would suspect that in 1965 it might have even been a couple points higher. (I recall that in the late 60's, when I was buying gas for lawnmowers, you could purchase 107 octane from the local Sunoco station pumps...!)
Today that 107 is racing fuel...!
I would suspect that in 1965 it might have even been a couple points higher. (I recall that in the late 60's, when I was buying gas for lawnmowers, you could purchase 107 octane from the local Sunoco station pumps...!)
Today that 107 is racing fuel...!
What engine do you have? If it's an original 283 or 327, it's probably got 10 to 1 compression or more. If that's the case, run a higher grade fuel as another poster suggests. Other things to try...You can back off the timing a couple of degrees, I'd say no lower than 4* BTDC initial and see what happens. You can also go back one or two heat ranges on the spark plugs. Dump some carbon blaster down the carb. Increase the jet size in the carb to make it richer. That's about all I got.
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What are you running? Engine specs, size, heads, compression ratio, cam and so on.
The rear end ratio , Fuel system,engine temp, how many miles on engine.
Warranty, when and what was done?
Your distributor, initial timing, total timing, vacuum advance. Grade of fuel?
What advance curve in the distributor? If your idle is high enough, and advance is coming in early, timing could be all over the place. Is the MSD proper for the engine you have? Is the distributor seated to the intake? Do you need an extra gasket on the distributor to make it tight? New timing chain on engine?
Why did you replace HEI if you bang it and the car died? Fixing it unless wore out would have been the easiest.
Maybe it didn't like the abuse!
What spark plugs are you running?
And the list goes on...........
The rear end ratio , Fuel system,engine temp, how many miles on engine.
Warranty, when and what was done?
Your distributor, initial timing, total timing, vacuum advance. Grade of fuel?
What advance curve in the distributor? If your idle is high enough, and advance is coming in early, timing could be all over the place. Is the MSD proper for the engine you have? Is the distributor seated to the intake? Do you need an extra gasket on the distributor to make it tight? New timing chain on engine?
Why did you replace HEI if you bang it and the car died? Fixing it unless wore out would have been the easiest.
Maybe it didn't like the abuse!
What spark plugs are you running?
And the list goes on...........
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608 Posts
Compression ratio?
9:1 I believe
Ok now that I can sit an answer. The motor was a crate motor by csd her in California. I have a 4spd muncie behind it. The original diet was a summit hei style. Knock off basically. I had a msd from my 355 engine before. I set total timing at 29 degrees now and it ran decent but still pinged when getting on the freeway tonight. My idle is at 800 right now. Idk the advance set ups right now. No vacuum as I stated earlier. The distributor is seated on the intake only 1 gasket no leaks. The plugs are #24 as I started with #26 and they were too hot. Thanks for the help
Ok now that I can sit an answer. The motor was a crate motor by csd her in California. I have a 4spd muncie behind it. The original diet was a summit hei style. Knock off basically. I had a msd from my 355 engine before. I set total timing at 29 degrees now and it ran decent but still pinged when getting on the freeway tonight. My idle is at 800 right now. Idk the advance set ups right now. No vacuum as I stated earlier. The distributor is seated on the intake only 1 gasket no leaks. The plugs are #24 as I started with #26 and they were too hot. Thanks for the help
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608 Posts
What is your initial timing at idle, and at what RPM are you getting 29?
For street driving, I run vacuum advance, would not run without it.
Here in Texas, I have to run 93 octane only from known good sources. You can tell quick when it is bad.
If CR is 9 to 1, you should be good as long as you plug range is cold enough, fuel mixture is fine, and timing is appropriate.
The HEI had vacuum advance, did it ping?
For street driving, I run vacuum advance, would not run without it.
Here in Texas, I have to run 93 octane only from known good sources. You can tell quick when it is bad.
If CR is 9 to 1, you should be good as long as you plug range is cold enough, fuel mixture is fine, and timing is appropriate.
The HEI had vacuum advance, did it ping?
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Are you sure you have the Timing tape on correctly?, have you verified by finding top dead center and seeing 0* on balancer? No way that motor at 9:1 can be pinning at 29*
at 9:1 you should be able to run 87 octane
Here is a great video on timing
http://setyourtiming.com/video.html
at 9:1 you should be able to run 87 octane
Here is a great video on timing
http://setyourtiming.com/video.html
I have a similiar 383 and have played with different timing set-ups,what works for me is 19-20 initial,14 degree stop bushing in dizzy,this gives me 33-34 total,run the vacuum advance!!!!!!!,your engine will love the timing at idle,stays much cooler,improved fuel economy,and wont run on when u shut it off, 383 dont like a lot of timing 32-34,you'll need a different vacuum advance can vc 1838 is the part #at napa,that should work for you,dont know exactly what dizzy you have,or what your vacuum is at idle i'll assume 13hg,the 1838 is for hei type dizzy,but if you have a msd 8360 the housing can be modified slightly to fit the 1838,you'll need some stop bushings from foursecondsflat.com,i didnt like the crane adjustable VA can to much spread in can on/off,get the initial working right first (VA unhooked)do hard acceleration runs and adjust dizzy for no ping,then VA,1 more thing,if you run the 10 or 14 stop bushing you will have to recurve,run the 2 heavy springs(curve comes in much to quick with anything lighter)your idle should be around 750 for proper vac signal to VA can,hope this helps
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OK I'm just conjecturing here - since this seems to be an elusive problem. So, MAYBE not the distributor or timing at all. Might it be ...
1. Some intermittent severely lean condition from carb problems, perhaps only on one half of the engine. (e.g. One side of the carb is lean...engine will start and idle, but under power will ping from leanness)
2. Carbon build up issues
3. Hot spots in a single or few cylinders caused by blocked coolant passages or somehow restricted coolant flow to some/all the top end
4. mismatched piston crown to combustion chamber issues (big dome pistons and little chamber heads somehow not playing well together)
5. Electrical grounding issues on the engine block causing erratic distributor performance
6. Errors in timing measurements caused by inaccurate "the finger" TDC method
7. Lack of vacuum advance pushes engine cylinder temp very high during lean idle and lean cruise conditions, heavy throttle combined with unnaturally high cylinder temps results in initial WOT detonation.
8. Some combination of the above...
Again, just throwing out some other ideas. Sooner or later if you can't stop the detonation with what you think and what sounds like severely retarded timing, then you have to look elsewhere.
1. Some intermittent severely lean condition from carb problems, perhaps only on one half of the engine. (e.g. One side of the carb is lean...engine will start and idle, but under power will ping from leanness)
2. Carbon build up issues
3. Hot spots in a single or few cylinders caused by blocked coolant passages or somehow restricted coolant flow to some/all the top end
4. mismatched piston crown to combustion chamber issues (big dome pistons and little chamber heads somehow not playing well together)
5. Electrical grounding issues on the engine block causing erratic distributor performance
6. Errors in timing measurements caused by inaccurate "the finger" TDC method
7. Lack of vacuum advance pushes engine cylinder temp very high during lean idle and lean cruise conditions, heavy throttle combined with unnaturally high cylinder temps results in initial WOT detonation.
8. Some combination of the above...
Again, just throwing out some other ideas. Sooner or later if you can't stop the detonation with what you think and what sounds like severely retarded timing, then you have to look elsewhere.
First of all, the "finger trick" only tells you when the #1 piston is approaching TDC but not when it is exactly on TDC. To find EXACT TDC you will need a piston stop and a preferably a degree wheel as well to make sure when your engine is truly at TDC when the timing mark (line) on the balancer is lined up with the zero mark on the timing tab.
Second, when checking for total timing don't just assume that 3000 rpms is the magic number to rev the engine to. You need to rev the engine steadily until the timing stops advancing, which in some cases could be upwards of 4000 rpms.
Third, 40 degrees is a bit too much total timing for the fuel you are running. I would suggest 35*.
What are the @ .050" specs on your cam?
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Which is all wonderful from the perspective of history, but since we are no longer rating octane at the pump the same way, it's also of little value.
Current octane ratings at the pump label are the average of Research octane and Motor octane: R + M / 2 = Pump octane
They used to use the Research octane number, which is typically ~5 numbers higher than the Pump octane number. In other words, 91 as specified at the fuel pump today is roughly equivalent to 96 octane of years ago.
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what pistons are you using? A flat top with a 76 cc head will give you close to 10:1, a dish will get you close to 9:1. what cam are you using? Can you give us head casting numbers and what pistons your using? what octane are you using?
Let me say I have zero'd out the timing mark as the shop that built it for me ensured me that was TDC. I have taken it to 2 different shop to see the timing issue as I stated before. I went by the instructions that I was given with the 3k rpm. FYI I never set it for 40 tt and never stated I did. The last shop I took it to today said they think I have too much compression and now have too much blow by and I should have them redo the rings as they have not set right. I am not a mechanic but I am decent with tools and cars. I appreciate everyone's insight.
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7,878 Posts
Can you give us any information in the heads and pistons used in this build? I have read that the Thumper cams need alot of initial timing and they have a tight LSA which builds cylinder pressure and if you already have too much compression as it is, this only adds to your problem. How many miles on this engine? Is there any kind of warranty? Have you talked to the builder about your problem? I have to agree that it sounds like you have too much compression.
http://www.csdengines.com/csd 383 thumper stroker.html
I will post casting number tomorrow. 91 octane only flat top pistons is what I was told. I am not going open the motor as I want to send it in for warranty and switch to alum heads if I have to pull the motor.
I will post casting number tomorrow. 91 octane only flat top pistons is what I was told. I am not going open the motor as I want to send it in for warranty and switch to alum heads if I have to pull the motor.
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