Pinging...still haven't figured it out

[Rooster's82]

So a couple of weeks ago i started a thread about my engine pinging when i didn't use premium gas and got a lot of good advice...I applied most of it but the engine still pings. (it actually started pinging with premium too)

First, I had the timing checked and set to specs.

I figured out my vacuum advance and corrected it. There are no leaks.

I ran some SeaFoam directly into my engine using a vacuum line. I was told that carbon build up will "glow" and cause pre-ignition. I think i did a pretty good job...but i think i could do it again.

I put in a new 180 degree t-stat, and did a very good flush, now the coolent is nice and green with no rust, there are no leaks. It calls for a 195 but because the engine pings worse at higher temp i thought a cooler t-stat might help. Funny thing is the engine runs at 195-200 now, why i don't know.

I also got the carb dialed in better, and gave her an oil change with 20W50 oil.

End result...

I have been running regular gas and it runs great until it gets to 195-200 then during mild acceleration it pings. regular cruzing speed NP...heavy acceleration NP.

I have not tried premium fuel yet but i have a feeling it would mask the problem...but don't know for sure.

When it pings the engine heats up like crazy (210-220 in a matter of seconds) and the pinging gets worse. I can drive the truck and prevent it from pinging...but i have to lay into it to do any type of acceleration.

Also at idle the temp starts to creep up. Which doesn't make sense...i have an electric fan that pulls way more air at idle then the stock fan ever did.

The previous owner dented the headers in 2 spots in order to get to the spark plugs....could this be causing enough restriction to heat up the engine and cause the pinging?

I should also add that previous to doing everything above if i put regular gas in the truck was nearly undrivable....now i can run it pretty well with regular...Basically i have made VAST improvements...but haven't quite eliminated the problem yet.

HELP...I don't know what else to do!

[Rooster's82]

here is a picture of my beast...I promised to do a before and after thread awhile back...but i have been lazy as heck. I will get to it eventually.

[Square84]

Yours Doesnt Have A Cat Does It?

[Rooster's82]

It has dual exhaust and a cat on one side...i don't know WTF the previous owner was doing but the exhaust is pretty cobbled together.

[dammitmitchell]

are you consuming more oil then normal? water?
could be a head gasket leak.....
hmmm...you shooting any smoke out your exhaust ?
hows your water pump if the temperature keeps rising so fast....
??
or i could be totally wrong.. its one of those days

[Rooster's82]

I replaced the water pump about a month ago, and when i flushed the system it was flowing well.

It puffs a little white smoke if it sits for a day or two...otherwise nothing.

I haven't noticed any unusual oil or coolant consumption...I'm going to go check right now to make sure....Nope plenty of coolant...still looks nice and fresh. Oil level is fine, nice and clean...i did the oil change about 3 weeks ago as far as i can tell it's at the same level.

[dammitmitchell]

wait only "one cat"??
like it's a tru dual exhaust with only one catalytic converter on one side?
or is a two collector that combines to a single pipe wiht a single cat then out to dual tips??

[Rooster's82]

Originally Posted by dammitmitchell

wait only "one cat"??
like it's a tru dual exhaust with only one catalytic converter on one side?
or is a two collector that combines to a single pipe wiht a single cat then out to dual tips??

True dual exhaust...one with cat one with out!

[Square84]

little puff when it starts is valve guide seals but i had the cat go out on my 90 burb and it caused all kinda probs over heating pinging running like crap at lower speeds all kinda stuff. cut it off everything works great now.

[Square84]

Originally Posted by Rooster's82

True dual exhaust...one with cat one with out!

it used to be single exhaust someone did a elcheapo daul setup they prob even weld over where the 2 pipes used to meet.

[Rooster's82]

Originally Posted by Square84

it used to be single exhaust someone did a elcheapo daul setup they prob even weld over where the 2 pipes used to meet.

I think you hit the nail on the head....there is all types of crap welded together under there.

I will stop by my buddy's shop and see if i can't chop it out tonight after work.

[COMP]

Originally Posted by Rooster's82

I think you hit the nail on the head....there is all types of crap welded together under there.

I will stop by my buddy's shop and see if i can't chop it out tonight after work.

that may do it ,,, it can be from a lean spot in transition

[dammitmitchell]

well yeah... wow... crap dud one side is runnign with minnimal bak pressure and the other is working "normal" ewww
dont u love it with PO's dude just seemign random weird things....
grrrrr.

[COMP]

don't forget to scrap that verter for $$

[dammitmitchell]

Originally Posted by COMP

don't forget to scrap that verter for $$

YES YES YES to that, every local craigslisting will have a dude looking for old converters, some pay well because of the precious metals in them, much niceer then PAYING to dump it

[knightlife]

I had the same overheating problem a while back too... it was my radiator.

might wanna do a radiator flush (lime is a PITA when it comes to stock radiators). bought a new one from radiator barn for 195 bux, free shipping.

[gchemist]

How clean is the radiator?

Try dropping to a 160. I ran a 160 thermostat during the summer. Temps would average 170-180 with a 454 aluminum radiator.

Your thermostat may not be opening all the way.

Drop the timing by 1 degree until it stops pinging. Iron heads hate heat.

[MylilBowTie]

May have to retard the timing to run 87.

[Rooster's82]

So, i pulled that cat off lastnight...it was totally HOLLOW...NOTHING...not a damn thing in it. How does that happen? do you think that the guts from the cat are now in the muffler? Maybe that is my problem?

I was under there for a while and really examined the mess that is my exhaust. The PO welded the pipes directly too the long tube headers. On one side the pipe is about 1/2 smaller than the header (lean spot?). One side is routed over the cross member (?) and the other is not. From the cat back(and where the cat should be) the exhaust and mufflers look pretty new.

I'm going to cut the entire section out from the headers to the newer section on the exhaust and replace it.

How can i check and see if the muffler behind my empty cat is clogged up? without having to dismantle the whole thing? I don't have an impact wrench.

Also, I drove the truck to work today with the exhaust disconnected on the cat side. This is also the side with a 1/2 smaller pipe welded to the header. Although the exhuast was pretty loud i thought i heard some pinging still! Could that lean spot still be causing the problem?

As far as the radiator goes...I pretty sure it is in good condition I have flushed it twice really well since i bought it and it seems to have good flow.


I have not messed with the timing to much...i was assuming that because the pinging occurred at higher temps, it was a heat issue. Could i be wrong?

The t-stat is brand new...i would assume it is operating properly.

Sorry about the novel...but i wanted to get everything in.

[dammitmitchell]

the cat is hollow because the PO took the cat off and punched out the insides himself that's all it isnt gonna be in your muffler, unles your cat has some serious damage to th outside, but i do not believe that is the case.
hollowing the cat is a cheap easy way to get past the safety inspection people for regristration while maintaining a high flow exhaust.

[Rooster's82]

Ok...so the cat wasn't the problem. Could it be the the "lean" spot caused by the smaller pipe welded to the header?

Who would i test the radiator? It looks good...when it was empty i didn't see any build up or anything that would cause alarm.

I think I'm going to have to start looking at the timing again.

[77 350 Shorty Wide]

What brand of gas Shell, BP, Tesoro, AMPM ARCO, or even an Independent are you using? Have you tried different ones? I know that sometime this can be the problem. I believe some of the higher quality ones like 76, Sunoco, Texaco, Shell, Conoco can make a big difference. God Bless, Terry

[COMP]

Originally Posted by Rooster's82

Ok...so the cat wasn't the problem. Could it be the the "lean" spot caused by the smaller pipe welded to the header?

Who would i test the radiator? It looks good...when it was empty i didn't see any build up or anything that would cause alarm.

I think I'm going to have to start looking at the timing again.

yes look at how fast it comes in ,,total etc.

[airdale94]

Originally Posted by knightlife

I had the same overheating problem a while back too... it was my radiator.

might wanna do a radiator flush (lime is a PITA when it comes to stock radiators). bought a new one from radiator barn for 195 bux, free shipping.

I agree with knightlife. Sounds like you're overheating, then the pinging starts. Then the more it overheats the more it pings.

[LONGHAIR]

First, I had the timing checked and set to specs.

I figured out my vacuum advance and corrected it. There are no leaks.

To exactly what spec? You may still need to retard it a bit. Once the pinging starts, it creates heat...that just makes it worse.

Second, the heat spike is coming from the pinging. Once it starts, is just grows upon itself. A lower temperature thermostat will not do anything. The thermostat is just the "switch" that "turns on" the cooling system. Once it is open, everything is based upon the efficiency of the rest of the system. This means not only the flow of the coolant, but over all heat exchange. The fan may be moving air, but is has to be removing heat with that air. If the fins are blocked of air, no much actual cooling happens either.

I am thinking that this is still an issue of the combination of timing and cooling efficiency....but lean carburetion can be a factor too. What carburetor are you running?