1989 Chevy Camaro Engine Knock! Need help narrowing causes

CAMARO_IROC_GUY

MEMBER
1989 CHEVROLET CAMARO
V8
2WD
AUTOMATIC
20,000 MILES

Engine knock on my Iroc Camaro. Need help narrowing down causes?
A little about my car. It is a 1989 Chevy Iroc Camaro with a Tuned port injection 406 in it. The car has an almost new 700r4 auto transmission with a small shifter improver kit in it. The engine is a 400 block Bored.30 over and has been balanced and blueprinted. The car also has.224 lift comp cam, 24ib/hr injectors(accell), Accell fuel pressure regulator, 9.1-1 compression, Hooker competition headers, a fast chip, Cam lift is.3180 and separation is 114. It has cylinder heads off of a 350 and they are not ported. Thermostat temp is 195'. Valve timing is set at.006 tappet lift is 258 and the gross valve lift is.479. Cam installed at 110 Intake center line, duration is at.050, lobe lift.3180, lobe separation 114.0.

So far this is the list of things I have that could be causing my Camaro to ping or knock.

Low grad fuel: have tried couple bottles of octane booster and a big one with minimal results
Rod bearings bad
Cracked flex plate or flywheel
Advanced ignition timing
engine is too hot
excessive clearance inside the bearings in the connecting rods
defective main crankshaft bearings
worn water pump bearing
failed or loose timing belt tensioner
air conditioning compressor
alternator with worn rotor bearings
piston rod journal knock

That is the list, basically I need to know how to go about slowly eliminating any or all of the possible issues that could be causing my car to ping before damage starts to occur.

The ping is a loud constant ping. It increases with rpm and comes from the back of the engine by the last header on the drivers side it sounds like. My engine does give off a lot of heat if that helps. I ended up filling the oil as it was low with 2 quarts 10-30 plus 1/2 quart of lucas oil stabilizer and it almost took the knock away. You have to get very close to the engine to even pick up on it and if you didn't know it had one you might not even pick up on it. I know that the knock will eventually return and this is only a temporary solution. Any suggestions on narrowing down this list of causes and any extra help on this matter would be extremely helpful and appreciated.

Thanks in advance, josh

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Couple of things to check are torque convverter bolts loose asthey will hit the back of the block and make noise. You header plate may bewarped and causing a noise. Usually you can put two header gaskets together with silicone in themiddle of one to solve this. Another thing may be the 350 headson the 400 block. They needto bedrilledby the center in two spots. Most lmachine shopes who modify these for 400's not where. It may also be due to the size of the cc's in the 350 heads on the 400 block. You could try a fuel like Torco which is racing fuel and see if that helps or eliminates it altogether. I fyou can't get that get 5 gals of 115 octane airplane fuel. You may also have to back the timing off to eleimante the ping. If your engine is running under 220 degrees all thetime, don't worry about it. If you have a stethscope to singleout the noise thats' ok, but if you have along screwwdriver you can put that in various areas and put to your ear and will pick up different noises to try to single it out. However, be very careful where you put it due to the engine will be running when you do this.