I recently installed ITR cams in my b20z/vtec - stock bottom end, stock head aside from different valvesprings and cams. I noticed a new sound immediately afterward, however I'm not entirely sure it didn't exist before. I'll explain the sound...

Neutral revving = no unusual sounds. Driving in 1st or 2nd gears, again no usual sounds that I can detect. Driving 3rd-5th gear at around 3500rpm in each gear starts a muted knocking sound. The sound increases with RPM and is louder and more distinct in each subsequent gear (more engine load).

Cruising on the freeway = very little engine load = no sound, so I know it's gotta be motor/drivetrain related. Push the throttle and I get the knocking sound. Increases in tempo with RPM, and increases in volume with added throttle.

Could this sound be a slight rod knock? I know most of the time with rod knock it's loud as hell even when revving in neutral, but mine seems to only pop up under heavy engine load. If it's not rod knock, any ideas as to what else this might be? Possibly transmission?

Thanks for any help,

Justin

 

sounds as if the vavles are hitting the pistons??

 

what compresion are you running? It could be detination. But, I think since you changed the cams it is probably the valves smacking the pistions....VTEC, more aggresive cam.....higher rpm....smack, smack, smack.....DUDE STOP DRIVING AND TAKE OFF THE HEAD CHECK YOUR VAVLES AND MAKE SURE THEY AREN"T BENT!!!! I mean it really sounds like you have been driving the car for a while in this condition. STOP

 

Yeah, im pretty sure the stock B20 pistons wont clear the valves with an ITR cam cuz the VTEC valves are bigger than the B20 ones, so the valve reliefs arent as big on the B20 pistons.

 

What rods are you talking about???? Pushrods, I agree but, if you aren't talking about pushrods what do you connect the pistion and crank with....bubble gum and duct tape?

And the Cam pushes on the rocker that opens the valve, all cams push the valves open just some use only rockers and others use lifters/pushrods and rockers.


[Modified by Spade, 5:47 PM 10/17/2001]

 

well said spade, was wondering what the hell he meant by that no rods????????

 

Sorry bro I was thinking about lifters.

 

It might be possible that the increased running compression from your new cams is causing knock/ping. Try to retard your timing a degree or two (ignition) and see if that helps. If your valves were hitting your pistons you would have more problems than just a little knocking and it would do it in any gear. The only thing that really changes with different gears is cylinder pressures from the increased load.

 

Its not rod knock. Do this test. Drive at around 25mph. Put it in 4th or 5th and floor it. If it makes a distinct knocking or pinging noise, you have detonation. ITR cams will clear a B20Z motor with no problems. My friend ran JunIII's with no problems for a little while anyways on his B20vtec. He decided to see if he could rev to 9500 on stock GSR springs and a B20 bottom end. Retard.

Its most likely detonation. Also you could do a compression test, and leak down test. Don't pull the head until that is done.

 

So, my removal of the head advise was bad N-E-Way, are you gonna give us a status on this or what? We all add to it and don't hear from ya.

 

Sorry I haven't replied to this yet, but thanks for all your ideas.

Valves are not hitting pistons. ITR cams clear in a b20z until you go way advanced with the intake cam.

I seriously doubt it's detonation. I can retard my timing a bunch (via the distributor) and the sound does not change. It also doesn't sound anything like pinging.

Rod knock. That's been ruled out by about everyone I've talked to, so I'm comfortable assuming that is not the problem? So then, what IS the problem?

I'm thinking now that it's transmission related... it only happens in three gears. Since before I thought it was based on engine load, I put on my a/c and drove up the steepest hill I could find. The noise was not present then. I also did another stupid test. I was cruising on the freeway, purposely making the noise in 5th gear. I then swerved hard to the left and right, and the sound was not there when I was swerving, but it returned when I started going straight again.

I think just by that stupidity of mine that this is not a motor problem. I'm going to swap transmissions this weekend. I will let you guys know. Thanks again for all your posts.

Justin

 

Swapped the transmission last weekend and..... the noise remains.

Swapping driver side axle tomorrow if all goes as planned. If that doesn't fix the problem I might just drive the car into a wall.. see if it still wants to make funny noises

Justin

I like these little icons....

 

put that bitch on a set of jackstands and have someone "drive" it

 

I had a knockind sound similar to what you described. Sounded like the piston was hitting the head in Cyl. 1 and 4. Took off the head and saw the letters "IN" under the head, shows that the piston stamped it on there. I had no bent valves at all, but I had spun rod bearings.

 

That was an idea I had at first, but it seems that this only happened under engine load. I can cruise at 60mph and hear no knocking, but as soon as I hit the gas, sure enough the knocking sound comes back.

I'll see if replacing the driver side axle does the trick.

Justin

 

maybe you just figured out the problem from doing that test. check your driveshafts/wheel bearings/brake calipers and caliper bolts. shifting the weight of the car from side to side and the noise goes away? i bet it's somthing i listed above.

somtimes drive line noises travel from one end of the car to the other. it might sound like it's comeing from the engine but really it's somthing else?

it "could" be a axel........the tend to knock and click and make all kinda of weird sounds when going bad.

check thouse out as well.

good luck.

 

YES!!!!!!!!

I am a happy boy now.

Swapped driver side axle (took 30 minutes, I must be getting good at this ) and the wobble went away!

YES!!!!!!!!

Thanks again everyone for your help and ideas.

Justin

 

Damn, this whole time it was an axle.....I had been wondering what happened yesterday actually and was gonna ask but, wow an axle.....hmmmm.....duley noted.

 

same thing happened to me, t was my drivers side intermediate shaft.