Hey guys, I have a 67 Skylark with a 340, factory 4barrel, (aftermarket Edelbrock carb). Stock distributor and dual exhaust. The timing seems to be right but I still get a little pinging when I really give er the gas. If I baby it, its not bad. Any tricks to stop the pinging. Should I just run really high octane? Thanks!
Larry, I'm not really sure, I just put in a new distributor and adjusted it to get it running the best. It says on the vacuum advance that it is tested and set at the factory so no adjustments need to be made. I realize that's just for the internal part of the distributor though. She's unfortunately running a little rich also. Maybe get it on a dyno???
Todd, The most common reason an engine will ping is over advance. Before you can consider other reasons for ping, you need to know what the total timing is. otherwise, you're just flying blind if you know what I mean. I wrote this post just for guys like yourself. http://www.v8buick.com/showthread.php?t=63475 Whwnever you replace the distributor in an engine, you need to check the total advance. The original specs no longer apply.
Scribe an index mark at the base of the distributor as a reference and retard the timing in small increments until the pinging is no longer audible under load. Don't be concerned with exact timing mark indications with a timing light as timing lights can vary in accuracy.
Todd what grade of gas are you using? According to Wikipedia the 340 that originally had a 4bbl carb has a 10.25:1 compression ratio. This will require mid to high grade gasoline like 93-4. If you want to use a lower grade this may require you to use less ignition timing.
Thanks guys! Nate, next fillup I will put the highest grade in and see what that does. I know they did require high octane from the factory. It is a factory 4 barrel car. I also see you are in Milwaukee, once this latest blizzard passes, ha ha, maybe we can check each other's cars out and you could give me some pointers on a tuneup? Thanks!
Hey Todd, we should get together. I'm not digging this snow. But it's not my fault. My snow blower is still ready to go. my car needs a bit of work yet. lots of tuning. Don't go too crazy on the highest grade (you shouldn't need racing fuel or AV gas). also you maybe able to get away with lower octane gas if you tip the timing down but where's the fun in that.
That's right! I want to advance the timing as far as I can!!! I had it out on St. Patty's day when it was 73 degrees, too bad it's not like that all the time around here!
Like Larry says, you need to set the timing with a light to really know where it is.... a 340 power pack engine is definitly a high compression engine... and it is easy to over advance the timing by ''timing by ear''.... dont do it .... you will grenade a piston..... Be sure that when you set the timing with a light that the vac line to the dist advance is disconected.... that way you get ''base'' timing.....now there is an old trick that you can do... start the engine up and warm it up... set the idle up to 800 rpm and then SLOWLY dribble about a glass full of plain water into the carb... you will here the rpm drop some.... the water will turn to steam and clean the loose flaky carbon out of the cumbustion chamber and blow it out of the exhaust system....have some one stand back at the exhaust pipe and hold thier hands there and they will be able to feel the chunks of carbon coming out.... Carbon inside the combustion chamber tends to be flaky and the edges of the flakes will glow red hot and detonate the ratty gas that we get now days... it is more like the ''drip'' gas that we used to get at the well head back in Louisiana than real gasoline that we used to be able to buy....
I like to go bigger with the size of the font everytime actually, but I guess I have to change the actual font itself too. Sorry for making u squint!!!
When fully warmed up what temparature are you running at? I used to get pinging under hard acceleration then I bought a alminum radiator that reduced the fully hot temps 15 to 20 degrees and got rid of the pinging. I was even able to advance the timing 2 or 3 degrees which made it run better/harder.
