Highway woes

[justhorsinaround]

Ko I have an idea what's up but I'd like to have some other opinions thrown at me if you don't mind.


The Blazer, with a 350, is pinging (clattering lifters) really bad at highway speeds of 60 and above i.e. higher revs after a trip of say ten miles or more i.e. really warm. At the beginning of a drive no issues at all. Makes some obnoxious noises at rather high street rpms as well but it's a different noise.

I keep retarding the timing but it doesn't seem to be making any difference. If you need some more detail then that's cool. Fire them questions and I'll answer as best as I can.

Any and all thoughts appreciated.

Thanks in advance.

 

[pauly383]

Well , its two different sounds . Pinging could be bad heads , bad gas , gears too high , too far advanced timing , bad vacuum advance , and a some things I forgot or can't remember . Clattering lifters sound different , as least to me .

Did you readjust the valves since putting those heads on ? Did you tighten the locknuts on those nice shiny anodized roller rockers ?

 

[Can Can]

Is your vacuum advance hose hooked up to the right spot on the carb?

 

[justhorsinaround]

Was thinkin about runnin the valves again, again after retorqueing the heads this weekend Paul. Wanna come over? To answer your question though yes I have run the valves since install.

And to Mister Canmore Canadian Guy Dude the vacuum advance has been in the same port since I bought the truck and it's only here recently that this problem has reared it's ugly head.

Oh and on the way home it decided to power it's way up to 75 with no clattering for a couple of miles then on the next freeway rise it wouldn't hold sixty without all hell breakin loose.

 

[pauly383]

I'll be there Sunday , you weldy frame , I'll help you back

 

[justhorsinaround]

Oh yea, huh.

 

[7blazer5]

My 75 k5 does the same noise. I haven't came around to fixing the problem but it seems to be comming out of the Distributor. Maybe my distributor is going out cause when I swaped my intake manifold and carburator, I dropped in my distributor incorrectly and drove it for a good while until I got it properly timed so now I think it's out. It's like a ticking noise. I have a manual 3 speed and at the end of every gear it'll do it moreHas anyone heared about a problem like this?

 

[pauly383]

I listened to it run yesterday , damn thing sounds nice . It starts on first turn of the key , jumps to life and idles sweet . Timing is good , and it revs nice . No lifter noise to speak of .

Maybe oil pump on way out , maybe distributor or vacuum advance while driving at higher rpm's

Maybe just bad gas , I assume he's running cheap stuff like me and sometimes big tires and stock gears ping a bit anyway