i'm getting engine load based pinging

[camshaftgsxr]

yep.. it happens only when its hot and only when i'm loading the engine, it sounds very metallic, like a thin metal rod being shoved into a metal bladed fan, when the engine has been up to temp for a while it becomes more sensitive to engine load (beginning to ping at cruise and getting much more pronounced upon accel.)

i recently got a new exhaust installed (professionally) and all the welds are clean but could a crack in a header or a gasket cause a temp related leak?

i also switched to 87 octane fuel but the pinging DID NOT begin the same time i switched fuels it began a month afterwards.

[STOCKISH]

Sounds like the timing is too advanced. Try going back to mid grade or premium fuel or turn the timing down a bit. If you're looking at the distributor from the front of the truck, grab the dist. and turn it clockwise just a little at a time and see how it reacts while driving. Unless you have a timing light which would make this whole process a lot easier.

[camshaftgsxr]

i do have a timing light it is set 14 degrees btdc at idle.

[87chevy.com]

man, i had a knock under load and it was a spun bearing...

[71swb4x4]

Back the timing off 2 or 3 degrees and see if it helps. I had my timing too far advanced once and it did the same thing you are describing.
Maybe the distributor is advancing too much at higher RPM's??? No idea, just throwing it out there. I am not an engine guru.

[camshaftgsxr]

*gag* nooooooooooo...... oh well... reason for a stroker

i will try other stuuf to make it go away first though

[jake wells]

either timing or excessive carbonized heads on it

[STOCKISH]

Put better gas in it.

[1986swb]

Does your 1984 Silverado have a stock engine (carb, manifold, etc.) or did you replace parts of it/or entire engine?

Try disconnecting the ported vacuum line on the carb that is connected to your distributor vacuum. Then plug the ported vacuum line and start your truck. Your truck will be running on its mechanical vacuum and hopefully it will not stall or have any hard starts.

This worked for me as I replaced my stock GM manifold with an Edelbrock Performer manifold (non-EGR) and a Holley Street Avenger carb. I had major ping issues at low RPM and tried different grades and types of gasoline, octane boost, adjusted timing (retard/advance) but none of these worked. However, after I blocked my ported vacuum line, and retarded the timing 1 degree, she ran flawlessly. No pinging, no hesitation, no power loss.

If this doesn't work, then maybe switch to an adjustible vacuum advance.

[camshaftgsxr]

thanks guys i'll try all of those tomorrow, its almost empty so ill fill it with premium and see if it does the trick if not ill plug the vac advance, (which i got into a big argument about ported vs manifold) and if that works ill get into the timing some..

[68GMCCustom]

8* base timing at idle should be plenty. 14 sounds like alot unless that was with the dizzy connected to direct vacuum.

[camshaftgsxr]

alrighty after the premium fuel i'll retard the timing, i advanced it to where it is because it ran better but it began pinging a month later and i dont drive it much so it wasn't a problem until i began driving it more

[gchemist]

Try running a cooler thermostat.

[mooseknuckles]

My 305 used to do that all the time under load, so I put in a hei curve kit unhooked the vaccum advance and backed the timing off. no more pinging.

[camshaftgsxr]

is the hei kit in the timing thread in the engine forum? if not would you please provide a link

also what temp thermastat

[PRattenbury]

Maybe go to the next cooler heat range spark plug.

[mooseknuckles]

Originally Posted by camshaftgsxr

is the hei kit in the timing thread in the engine forum? if not would you please provide a link

also what temp thermastat

The curve kit is a couple of weights and some different springs. I replaced mine, they were pretty worn and I used the heavier springs. It was from Mr. Gasket and its under $10. Most use a 160 degree thermostat when replacing them, but I kept the 190 in mine cause I drive it in the cooler weather too. Pull the vaccum line off the vaccum advance and plug it and take it for a drive, If it quits pinging you have too much timing. I dont have my vaccum advance hooked up at all with the curve kit.

[LONGHAIR]

I don't have time to go into the whole thing right now, but removing the vacuum advance is NOT a cure. It might be used as a testing tool, but not as a perminent "fix".

More later.