I bumped my timing an eighth and now its sounds like it has a rod knock, i cant remember or didnt notice if it was there before but I know the trucks will idle a little differently.

From what I can hear its comin from the back of the pan and speeds up as i give it the throttle.

Do yall think its a knock or normal idle noise?

 

Before you panic check your flex plate for the knock. It may be a rod knocking but it would have more than likely been making noise before the timing bump. How far do you have the timing bumped. Back the timing up and see if it goes away. It very well may be nothing more than a compression knock. Did the p.o. jump a tooth on the timing? If so it may be too much timing for your application. Good luck.

 

Ya the flexplate does make sense, I shoulda thought of that. I had a 71 mach 1 that ovaled out the flate plate boat holes and it knocked like hell, also i dont have a flexplate cover and it doesnt spin uniformly when running.

 

That may very well be your knock then. I'm not sure if there is room to see if it's cracked or not but maybe with some good light and a small mirrow you might can tell. Good luck with it.

 

Well usually the timing bump makes the engine quieter, so what i think happened is this knock has been there but you couldn't hear it until now , If the inspection cover was already off, someone may have already been in there.

 

In my experience the timing bump increase results in a louder engine, not quieter...more "dieselly" sounding than anything. I'd be surprised if there was anything going on that you couldn't have heard before changing timing...unless you ran the hell out of it and damaged something.

 

I had my timing bumped 1/8 or so. Then I did a cam swap and bumped the timing a tooth while I was there which is another 5 degrees of advance. That thing rattled something fierce when I first fired it up. Sounded like a rod knock. I backed it off a little bit externally and it sounded more normal again. I would back it off a bit and see if it goes away. If not, I would also suspect flexplate. My friends auto truck cracked the flexplate almost all the way around the crank flange. Made a serious racket. I mean REALLY loud. Also know a guy that had his torque converter bolts come loose on his 73 'cuda that made a knocking sound. Good luck.

 

yup... advancing made mine sound louder at idle... maybe a little better once revved up though.

 

Does the knock sound anything like these two short video's of my KW with a Cummins Big Cam 4 knocking. The second one is shacking because I'm about to cry sitting on the Grape Vine.

http://www.youtube.com/watch?v=9ks9T6cPxxI

http://www.youtube.com/watch?v=GVNLx0UsVzE&NR=1

 

Holy Moly Mike Mc the grapevine did you in. In 1980 the scale house at the bottom about did me in.

 

That sounds sick.

In all of the engines sounds that I have heard in all my years a rod knock sounds the most haunting with its metallic rap and also the easiest to spot once the pan is off, look for the blue bearing cap.

How far did you have to get towed?

 

Jim, I bought this nice old truck with a piston knock and registered it as a historical truck. The in frame rebuild cost waaaaaay more than I anticipated. 200 miles after the in frame the new #2 rod bearing failed (thats why I was crying on the road side). The company honored there work and put a brand new crank in at no charge. They even paid the 70 mile tow bill.

This is what it sounded like when purchased
http://www.youtube.com/watch?v=pGatx...eature=related
http://www.youtube.com/watch?v=c2_k4QvQmPw&NR=1

The piston knock is so light you can still hear the rest of the engine. The rod knock is so load it drowns every thing else out . They figured during the in frame rebuild the #2 oil passage picked up a restriction.

 

NOOOOO its doesnt sound anything like that, You have to get under the truck to really hear it, sounds like a small gas motor knock.