RATTLE IN A BIG BLOCK CHEVY

[entodad]

Hmmmm,
I had a sbc 350 that rattled much like yours for a couple of years,  I could hear it when I put it under power, and sometimes when you let off.  Listening around with a stethoscope I could hear it towards the back of the engine, but I just couldn't find anything that could've caused it....
finally it got so bad that I jacked the car up and listened from underneath with it running, still nothing....

I turned it off and was putting the cover back on and i noticed a line in the flexplate that looked odd...when I unbolted the torque converter and flexed the place....it was partially broken around the rear flange of the crankshaft...never seen that before or since.  However, I wouldn't rule that out here...unless yours is a std tranny...

Hope this helps

Doug
BTW...On my way to Illinois...new job and such....

[348tripower]

Hmmmm,
I had a sbc 350 that rattled much like yours for a couple of years,  I could hear it when I put it under power, and sometimes when you let off.  Listening around with a stethoscope I could hear it towards the back of the engine, but I just couldn't find anything that could've caused it....
finally it got so bad that I jacked the car up and listened from underneath with it running, still nothing....

I turned it off and was putting the cover back on and i noticed a line in the flexplate that looked odd...when I unbolted the torque converter and flexed the place....it was partially broken around the rear flange of the crankshaft...never seen that before or since.  However, I wouldn't rule that out here...unless yours is a std tranny...

Hope this helps

Doug
BTW...On my way to Illinois...new job and such....

Thanks Doug,
 Something else to check!
Don

[348tripower]

I spent the better part of yesterday chasing the dreaded rattle.  I changed distributors and timed the engine to stock specs. Still rattles.
 I unhooked the torque converter  and checked the flex plate. Nothing.  
Now I am suspecting the converter. This is a 350C trans. It has a lockup converter.  Taking the car down the road and letting it shift up thru the gears, I have a very loud rattle untill the trans is fully shifted into the next gear.        
Driving down the road I can cause the rattle by pressing down on the pedal.  Let off and it goes away stand on it and it goes away.
Maybe Crosley can shed some light on this?
 I wish I had access to another trans to try.
Time out today to take the 48 truck and the teardrop to Coldwater.  Gonna test the trans in this and see if I have the converter lock up fixed.
Don

[dragrcr50]

I spent the better part of yesterday chasing the dreaded rattle.  I changed distributors and timed the engine to stock specs. Still rattles.
 I unhooked the torque converter  and checked the flex plate. Nothing.  
Now I am suspecting the converter. This is a 350C trans. It has a lockup converter.  Taking the car down the road and letting it shift up thru the gears, I have a very loud rattle untill the trans is fully shifted into the next gear.        
Driving down the road I can cause the rattle by pressing down on the pedal.  Let off and it goes away stand on it and it goes away.
Maybe Crosley can shed some light on this?
 I wish I had access to another trans to try.
Time out today to take the 48 truck and the teardrop to Coldwater.  Gonna test the trans in this and see if I have the converter lock up fixed.
Don

I think you are on to it, in my days a service manager at ford, we would kill each cylinder and see if the noise stopped when we found which cyl it was we wo go there.  I suspect not hitting the head but a skirt bad or broken or perhaps a vlve hitting piston but if so it should bend and give other symptons.  i thi8nk id go with broken piston skirt or too much clearance around said piston..  my 2 cents , good luck...

[348tripower]

We have narrowed the rattle down to a loose wrist pin.  Being as the rattle becomes  noticable when the engine is warm, it starts at about 2000 rpm and goes away when we let off or really lean on it.
I checked and replaced the flex plate, checked all the valve adjustments and changed distributors, nothing helps.
The oil filter went to Roush racing this morning to be cut open and checked, no foreign matter was found.  
 Gonna drive it till fall and pull it apart.
Don

[Jbird]

You don't have a cam lobe or two going flat do you? I just did a 396 with a similar rattle, found one flat lobe and two on their way out. Just something else to check.   Jbird

[348tripower]

You don't have a cam lobe or two going flat do you? I just did a 396 with a similar rattle, found one flat lobe and two on their way out. Just something else to check.   Jbird

 I don't think so. This thing runs way too good.
Don