Running rough and loud pinging

Hi all,

Recently my 305 has been running very rough and vibrating a lot at idle. It's also making a fairly loud pinging sound on the right side of the engine (passenger side)...

Could this be a bent valve or something? I'm afraid to drive it and have stopped because it's quite loud.

Is there something I should check first? Could the timing be off and if so would this cause this symptom? What are some things I should check before I consider rebuilding the top of the engine or buying a 350 instead?


BTW, I have been driving it a little more aggressively lately ever since flipping the air filter cover over haha... (I'm wondering if I hurt the engine). I don't floor it more than a few times a day though and never hold the gas to the floor for longer than a few seconds.

When I checked the engine I noticed that the air filter had been crushed or sucked in. (Is the engine even capable of crushing the air filter by sucking in too much air)? The filter is not too dirty and should not be restricting too much...

Thanks.

1985 Caprice 305 SBC with about 110,000+ miles on it.

-Has had minor fuel delivery problems for a couple of years and the idle has to run about 100-200 rpm higher than specified to keep from stalling.
-There is quite a bit of smoke that comes from the oil filler cap and PCV (so both valve covers) it has been like that for a year or two. It's not a huge amount of smoke though.
-No smoke comes out of the exhaust; sometimes only a small amount of smoke upon start up and more smoke at start up in the winter.
-Oil has been recently changed and the level is correct; last oil change was 4,000 miles ago (I usually change every 3,000 miles).
EDIT: Could the 110 degree weather here in AZ be a factor? Perhaps the fuel is pre-igniting? -- I have never had the air filter cover flipped over (allowing more air in on demand) during such high temps as these.

The flipped lid could be the cause. Getting just that little bit warmer air coming in could cause that I suppose. Try putting back to normal and see what happens.

the air filter got sucked in because the high heat melted the air filter housing...where you live you want to have 2 air intakes from air outside the engine compartment ...3inch dia aluminum flex ducting and cut holes on each side of the air filter housing to mount them ..this with the air filter mounted correctly...

now cooler air from the grill will enter the engine and the engine should have more power and less pinging..

vacuum leaks will cause pinging /overheating also causes pinging..

home depot has the metal/ducting / rivets to do this mod..

Thanks. I actually tried running it last night, it was only about 80 degrees then, and it ran normally.

I also found out that the radiator cap failed and that it would not allow the coolant to purge to the reservoir (which tells me the engine was probably running way too hot). -- So I guess this was likely the problem; however, I do also like the cooler-intake-idea and will consider that.

Thanks. I actually tried running it last night, it was only about 80 degrees then, and it ran normally.

I also found out that the radiator cap failed and that it would not allow the coolant to purge to the reservoir (which tells me the engine was probably running way too hot). -- So I guess this was likely the problem; however, I do also like the cooler-intake-idea and will consider that.


with the radiator cap bad you have no coolant pressure this then causes the coolant to boil then the pinging from high temps...

the cold [ram air ] I did do this on my 1983...towed my boat 4,2oolbs upto the white mountains in NH ..ater this mod was completed [used only in the summer] my car had no problem going up those grades..before I had to use 2nd gear ...just kept it in 3rd gear ...

the design I used is basicly the same as some olds 442 had back in the late 1960's...

the design I used is basicly the same as some olds 442 had back in the late 1960's...Sort of like this?

http://www.teds-olds.com/1967_W-30_engine_sm.jpg

(from http://www.teds-olds.com/1967-442.html )

Sort of like this?

http://www.teds-olds.com/1967_W-30_engine_sm.jpg

(from http://www.teds-olds.com/1967-442.html )

thats about it on what I did ...like I said the added air in the summer heat when towing helped on the power ..

now this is a 400cu 350 hp vehicle so you with your vehicle don't need as large a flex ducting as this one used ..3 inch duct should be ample..air intake should be entering forward of the radiator mounting area ..

since its 120deg f out your way have you done this cold air intake test yet ?

Not yet :/ Been busy w/ school and a new job fixing muscle/classic cars haha...

Hopefully I'll have the time sometime... But the summer does stick around for quite a while here so I should be able to before it ends.

I put 89 octane in now and it seems to help a bit -- it doesn't loudly ping although I have not driven it long distances recently.