Oh man you guys are making me pretty worried about my engine!! :ball: First thing I do is going to be to check the oil filter on Monday . . .
Don't be too worried just back off the timing 3 or 4 degrees and take it easy on the engine till you can sort out the air fuel ratio with the carb mods. Things like carbon build up in the engine can make an engine ping, so you never know... I had issues once with a 350 that was grandma driven and had HUGE amounts of carbon build up... I could only use 28 degrees of timing or it would ping. After using seafoam down the carb and some burnouts and a ton of carbon came out the exhaust over the next few weeks and then it ran way better and I could raise the timing to 32 degrees. You may have to remove the spark plugs and inspect them, the detonation may have damaged the plugs.
A Crower level 4 cam installed at default location (or 4* advance) is sitting at 70* IVC, which won't bleed off anything when the OEM cams sit even later between 71* and 75*... Installing it at 0*/0* would still give 74*, which would do nothing to change the static bleed off, and could in fact exacerbate it with the increased overlap and cylinder fill at higher RPMs. According to the wizards here on the boards, those engines never had more than slightly over 9:1 with the extra iron slathered over the book spec deck height (even though rated at 10.25:1), so if it's detonating heavily off 92 octane, it should raise a few eyebrows. My '68 350 ran at a true 10.17:1 SCR with steels, but apparently I don't know how to (or never have) measured a deck height before. If it's not the ignition or fuel, there's really not much else left. Only thing one could do at that point would be to take steps to lower the compression (take off the steel head gasket and put on a composite gasket) and/or back down the timing. Trying to get it to run a bit cooler would help too, with a 180* stat. It doesn't ping when it runs cold, there's a clue. Just my 2c. Flame away haters.
Good points about the seafood and the excessive temperature... Here is a story for ya.... I had a 1991 Chevy truck that had a thermostat get stuck closed when it was -38 out, yes -38!!! Anyways long story short the truck overheated and I was trying to limp it to the nearest gas station when it blew the rad hose... I got out, cut the rad hose shorter and limped it some more, before it blew the rad hose a second time... Made it there safe however the engine would detonate and ping heavily as the engine got too hot... So yeah make sure it is not running to hot. And do not trust the timing number, just back it off it is pinging. Oh and by the way changing the timing will effect the amount of air and fuel needed so keep an eye on that as well... A perfect air and fuel ratio with a given timing curve will change when the timing is changed.... Seafood for thought LOL!
Hahahah :grin: Thanks for the tips guys. I know my balancer is good, had it rebuilt when I did the distributor, then verified the mark with a piston stop. I also put in a new TA 180 thermostat when I did the intake, usually runs at 180 at cruise, and on a hot day it will sometime get up to 190 or 200 at long stoplights. It would probably overheat if stuck in bad traffic and super hot weather. But maybe my cheap temp gauge is off and it actually runs hotter? I will back off the timing and mess around with it some more. Maybe dump some seafood down the carb, Sean did you use a whole bottle? Just slowly pour it in while running? I have to change to oil soon anyways so I will take that opportunity to cut open my oil filter. I will post again with what I find . . . or don't find! ray:
Starting off with a detonation problem...it might be a really good idea while it's apart (if?) to use a 160* thermostat until you get things under control. Efficiency and supposed longer life can come later. It's worth a few full octane numbers towards knock tolerance. Anything you can do to reduce the temp of air coming in does the same.
200* or less is considered normal for a factory engine. Keeping it between 180 and 210 is ideal. If the factory nylon gear skips a notch (or more) it will retard the timing, not advance it. This can make it run hotter (and weaker, and make it skip, etc. depending on how far it jumped), but won't normally make it start detonating unless the increased temperature puts it in that zone. Too early of an intake closing will boost dynamic compression which will make it require higher octane or otherwise ping on a lower grade of fuel (lower octane rating). IF it's the original OEM cam (or OEM replica GS cam), timing is set right (including valve timing, ignition timing, and distributor isn't having issues), damper is good, fuel is good, and it's running at less than 200*, there's really only one thing left... You could try to get it to run as cool as you can get it. I'd normally not recommend a 160* thermostat, but... ...and even this won't fix anything unless you can keep it there. Temperatures of 180* or more are recommended for proper oil temps (burns away condensation, fuel, etc. in crankcase), or back down your ignition timing, which will 'detune' it so it'll run on lower octane (92) but won't have the full power potential it could have. A more long-term fix would be to take your heads off and replace the steel gaskets with composite gaskets, which will lower your static compression ratio about half a point, which should be enough to let you run your engine at normal temps and a better ignition timing setting. There's apparently an anomaly with the Buick 350 and its factory performance--some ran way better than others (usually the early models) as well as fuel requirements. Some report the same findings as I--that their 350 had closer to advertised compression ratio, while others say their findings were much less. I guess the deck height varied as much as performance ratings throughout the years (and would explain the performance/fuel requirement differences). Perhaps the ones that showed closer to advertised compression were blocks that needed more machining to true them up, bringing the deck height closer to 'book specs', which is why they added so much more and why other blocks that trued up with little machine work had so much more deck height? It would make sense. Octane ratings in 1968 were 99 octane for premium and 93 octane for regular, and these were leaded gasolines with no ethanol added. This added plenty of leeway on octane requirements for varying compression ratios in those years from different manufacturers. An octane rating of 93 leaded/no ethanol would have been plenty for any typical Buick engine in those years, if the tuning was properly set. Another point of interest is that the Buick 350 wants more spark advance to run best, and so lower compression ratios would accommodate this much better than higher ones. Ratios around 9.5:1 SCR seem to be the 'sweet spot' for 91-93 modern day octanes and plenty of advance with cams ranging between 71*-75* IVC points. Different cams, timing settings, and actual compression ratios (as well as ambient engine temperatures) will cause these figures to vary somewhat, but as a general rule, are applicable. Hope this helps.
Funny thing is I was typing out a response that said pretty much the same thing, and didn't see your response until just now after I submitted my reply. :grin:
Haha. If you DO happen to have some head work done... make sure you have full contact pattern, wide exhaust seats. It will keep the face of the valve much cooler. This can be a major contributor to detonation problems.
Thanks for the tips guys, and yes Gary that is a very helpful post! The engine isn't currently apart, and since I'm going to be focusing my efforts more on building the turbo 350 for the next couple of years, I'm not sure that it makes sense to pull the heads. Today I changed the oil (Brad Penn 10W30) and dialed the timing back to about 28 total. I'll have to take it for a drive this weekend to see if it still pings. If lowering the timing doesn't work I will buy a 160 stat and work with that. I just want the engine to run well enough to drive normally I guess, being able to go WOT would be nice but isn't completely necessary. I can baby it for a while and be patient while I save up the $$ for boost. What's the lowest total timing I should try running to see when the ping goes away? Would a really low total number also be bad for the engine? Also here are some pics of my old oil filter, does it look ok? I've never taken one apart before, it was kinda a PITA!
Well I sprayed a whole can of Seafoam down the carb while reving it and a ton of white smoked dumped out of the exhaust! Unfortunately this didn't stop the pinging, but I may do another can of the stuff to make sure it's as clean as I can get it. Then I tried lowering the total timing to about 28 degrees. I only have 0 and 30 degree marks on my balancer so it's kinda hard to tell exactly where my total is. I've tried timing tape but it always falls off. Anyways that even didn't stop the pinging. With ~28 total my idle is at around 4 degrees. Then I installed heavier springs and this is what stopped the pinging. I'm using an MSD kit and I have the second heavyiest set on there (one heavy silver and one light blue) so I think now my total is coming in somewhere around 3000 to 3500 rpm. With this setup the car bogs bad from a stop but no audible ping on the top end. Runs fine on the freeway. I'm going to try raising the total back up to 30 while keeping the heavy springs in and see how it runs. I'm thinking that it was the timing curve causing the ping and maybe not the total degrees? This is all with the vac advance plugged.
Maybe consider converting to E-85, you shouldn't have a problem with that fuel because I think its over 100 octane. You can use the cash you were going to spend on the Riviera. The carb will need to be upgraded or swapped to run E-85, also your fuel line from the tank to the engine compartment will need to be stainless steel tubing, the rubber hoses will need replaced to something E-85 compatible and maybe fuel pump will need upgraded not sure though. No seafoodlaugh needed to clean the inside of the engine running E-85 as well because that fuel will be the cleaner when it burns. That is one of reasons it is so hard these days to read plugs even with the regular E-10 that we're forced to run(unless most of us drive many miles to fill up with pure gas) because the ethanol cleans the plug before it can be removed and read. I have seen that E-85 is 50% less than gas right now so because it takes 30% more of it to go the same distance as pure gas, it is still less expensive to run you'll just have to fill more frequently. GL Derek
You can use the timing tape to copy the marks, sharpie works well. Leave the tape off. So does a light ding with a stamp or tiny chisel. The idea of slowing the curve is good. This could be a big part of the problem, keep in mind it could still be doing damage silently. You'll have to expand out the oil filter or rinse it over a paper towel to look for grit.
With that much timing out and still got ping to the point your at 4 advance . You have other issues that are not being addressed and most comments here are leading you in the wrong direction. First you need to find your actual engine temp and if rear of engine isn't hotter then front due to flow of coolant problem. and you need a meter in car so you can read exhaust sensor. So you can tell how lean and when. Is it lean under load, wide open, cruise , light throttle. . Then you can see what adjustments to carb are needed. You did timing and that does not appear to be the problem. Lean issues can cause a overheat like condition. Go with the suggestion from Ken on jetting changes and try that then see if timing can be brought back up. I feel you should be able to run 8 at least. Also if you didn't change pcv valve do so.
Maybe I'm misreading the same post? Timing at idle and just off idle accounts for the sluggishness at only those rpms, and would be completely irrelevant at the converter flash speed or at the total timing amount (middle rpm range where detonation risks are higher) The mix may very well be too lean...but, Can't keep hammering on it while creeping up on jetting, or the next post will be "why is there glitter in my oil?" It's safer (esp. for a novice) to pull back timing first and then creep up on the tune.
I still have the oil filter, so I will try and take it apart further to check for metal. Well I moved it back up to 30 total with the heavy springs and back came the ping. This is driving me nuts, especially since I know that I'm potentially damaging the engine whenever I drive it . . . It's weird because the pinging does seem to change when it comes in, but one that that'll always make it ping (unless the timing is at 28 with the heavy springs apparently) is driving on the freeway in 3rd then flooring it so it kicks down to 2nd. Any time I ping I lift off the gas immediately. I may try 28 or 26 total and lighter springs? Maybe this will let is advance a bit at idle so my acceleration isn't so terrible but it'll stop the total timing short. Also tried switching to BBB secondary metering rods per Ken's suggestion to no effect. He said if that doesn't work then try jets, but I'm going to put back the stock rods and continue messing with the timing first. Someday I will figure this out . . . I just hope the engine doesn't blow before that.
PCV valve is new from TA, changed when I did the intake. I have a multi meter in that car and have been reading the O2 sensor. It's weird, sometimes it will read rich to normal (800mv to 400mv and up to 1.5k when I gas it) and sometimes it will read very lean (50mv - 300mv) and not change when I give more/less throttle. I hope I've hooked it up right. Got the wire from the 02 going to the positive of the meter and the ground of the meter going to chassis ground. Maybe I should get an in-car vacuum gauge too as this was suggesting on the same site where I read the 02/meter trick. Either way the readings are hard to make sense of, but I'm still new at this. To get the temp reading correct should I test the temp gauge I have or just invest in a nicer set of gauges?
