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Discussion Starter #1
i just rebuilt my engine and there is a knock.

its a 1965 289 block bored .030 with a 302 crank and moly rings.
302 4v heads, rebuilt by myself.

the knock only occurs when the engine is hot/warm.

at first i thought it was the fuel pump... nope. still had the knock without it.
then i thought it was a rod bearing... but the sound doesnt get louder with rpm. then engine only has like 6 miles on it. i did a rpm drop test to see if it was a valve, but all them dropped about the same. engine runs strong, so idk what it is. its a hollow knock like something is hitting. i thought it could be the oil pump hitting the oilpan, so i removed and adjusted that with no luck.

i think it could be a faulty lifter. the engine has all new parts... cam, lifter, chain, ect. if you have any suggestions or other tests that could narrow it down that would be a huge help. im going to invest in a stethascope soon. homefully that will help.
 

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I had a 302 built years ago, and it started knocking also.
Turns out the shop installed the wrong thrust bearing...so the crankshaft endplay was WAAAY out of limits. I could grab the harmonic balancer and move the crank fore and aft...totally wacked. Turns out end play was like 1/4" when it should have been .015" or something.

Just an idea..check crank shaft end play.

Joe
 

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You changed the crank, did you change the rods also? 302 has shorter rods with the longer stroke 302 crank over the 289. Could be valve to piston clearance once things warm up.
 

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Discussion Starter #4
yea i changed the rods. i did check the thrust when we were building it... it was alot more than spec, but i hoped it wouldnt matter. i was hoping not to take the oilpan off again... but that sucks. is there a way to check the thrust while the engine is in the car?
 

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yea i changed the rods. i did check the thrust when we were building it... it was alot more than spec, but i hoped it wouldnt matter. i was hoping not to take the oilpan off again... but that sucks. is there a way to check the thrust while the engine is in the car?
Not sure on that one. Grab a hold of your harmonic balancer and give'er a good back and forth action...youll know if its too much. If it clunk clunk clunks pull the oil pan and start measuring.
Maybe a dial indicator fixed to the block and measuring at the balalncer?

Maybe one of the motor masters can answer that.

Joe
 

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Did you use Plasti-gage to check the clearances on the rod bearings before final assembly? Realize once the engine heats up, the oil viscosity drops and if there is too much clearance you will get a knock. Avoiding dropping the pan at this point will only assure you of potential further damage. Something is not right internally and it won't heal itself. Frustrating but fixable.
 

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I would suspect crank end play if you checked it and it was out of spec....I did the same as you, 289 hipo block and caps with 302 rotating assembly, my crank end play was right in the middle of the tolerance and no knock....
Are you sure you have the rods in all the correct positions(face to face and face to crank)?
 

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Hi Bud,
You might be able to check the end play (as someone mentioned) by positioning a dial gauge to contact the damper. But first, use a "dead-blow" hammer to seat the crank towards the rear. Position the gauge, then slowly pry the crank forward. Take a reading. Rotate the crank 180 degrees and take another reading. If it's out of spec. Pull the pan, R&R the thrust bearing. ( it can be done) Re-check!
Good Luck!
 

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Discussion Starter #9
thanks alot you guys. i will check the thrust bearing.

this noise is so confusing. the knock is once per valvetrain rotation, but its a deap knock that sounds like lower end. i thought it could be a cam beaering also... we didnt replace those since they looked brand new.
im going to check the bearing right now. thanks for all the input. ill let you guys know what i find
 

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Discussion Starter #10
i forgot to mention that the noise does not change with engine load or spark. when it was hot i cranked it without the coil plug wire and it could still be heard.
 

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So you can hear the noise while cranking the engine over?

What does it do when in gear? Is it a manual or automatic? If manual what about clutch in/out?
 

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Discussion Starter #12
yes it can be heard while cranking. when it was warmed up and making the knock i turned it off, removed the coil wire, and cranked. the knock could still be heard. its an automatic. when i put it in gear the noise stays the same. under load or at idle in park the noise is the same volume.

havent checked crank play yet. just got a stethascope, but its to dark to do anything right now
 

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Let us know when u find out the problem. Because i just rebuilt my 289 and the it is going to a pretty good engine. But if i might end up haveing a problem with it that i would have to resolve so. So i will look out for this problem on mine.
 

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Discussion Starter #14
im waiting on the dial indicator guage. i remembered the 302 crank came out of an engine bored .030 over and was very worn out. its possible they had oversized bearings to compensate for the crank wear. i still have the bearings from the 302 block... is there any way i can tell what size they are by the numbers or serials on the bearing?
 

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im waiting on the dial indicator guage. i remembered the 302 crank came out of an engine bored .030 over and was very worn out. its possible they had oversized bearings to compensate for the crank wear. i still have the bearings from the 302 block... is there any way i can tell what size they are by the numbers or serials on the bearing?
Are you saying you assembled the engine without checking the bearing clearances and just installed "stock" bearings?
 

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Could be the flex plate/fly wheel is cracked, I had that problem one time and it sounded like a knock in the engine.
 

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im waiting on the dial indicator guage. i remembered the 302 crank came out of an engine bored .030 over and was very worn out. its possible they had oversized bearings to compensate for the crank wear. i still have the bearings from the 302 block... is there any way i can tell what size they are by the numbers or serials on the bearing?
I'm not sure what you're trying to convey here, but, here's what should happen.
A reputable shop will "mic' a crank to determine the wear. If worn beyond a nominal value, they will, typically, turn the crank to accommodate a bearing .010, .020 oversize etc. Bearings are purchased as STD., .010, .020, or .030 over to match the smaller re-ground journal. The stamping on the back of the shell will reflect these values.
I have heard of bearings that are available in lesser values to compensate for minimal wear, such as .001, or .002 etc. Personally, I've never used nor needed them.
In all cases, it is considered best practice to "mic" each journal, compare to the factory spec. Then with all else being good, obtain a bearing that allows for the clearance spec. you're seeking and install. In the case of the center bearing, it has two purposes; first, to act as a bearing in the classical sense and, second, for "thrust" clearance (fore and aft or back & forth) play. Typically, when the engine bottom end is mocked up to check the clearances, the tech as part of the assembly procedure, would gently "smack" the nose of the crank to aid in setting or relaxing the thrust bearing, after which, a dial gauge is set up to measure this "fore and aft" clearance.
A reputable shop should document all of the values and have them available for you. I would highly suggest, you ask them to document their build specs when you offer the job to them and get it as part of the build agreement.
As an example, when I rebuilt my last engine the crank end play was listed with a tolerance spec of ".004 -.008". Mine when finished, spec out at ".004".
I realize this may be way more information than you wanted to receive, but, I feel like it's important to know how all of this "stuff" ties together.

Hope this helps.
 

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Before doing anything major I'd pull the bell housing sheet metal plate and look at the flex plate weight for scrapes. You might not have lined up the torque converter drain plugs with the holes in the flex plate and the counter weight maybe hitting. Put a socket on the damper bolt and rotate the engine one complete turn and look for evidence of interference. I had similar noise and found that my flex plate was warped.
 

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Discussion Starter #19
for everyone that thinks its my flexplate, i dont think so. i bought a new one when i assembled the engine. and its a knock, not scrape. and only occures when hot. so its something to do with the oil thining out and making it louder.

i am ashamed to say that plastiguage is the only thing i didnt do. the previous engine i built ran perfect with the bearings i installed. my thrust was about .028- .035 on this one if i remember correctly. so thats WAY more than there should be.

i have 2 options. trying to measure crank play and getting the proper bearings, and then attempt to replace the main bearing from underneath the car, or pull the engine, taking it apart, and doing it right. replacing all the bearings with the correct size ones.
what do you guys think?
 

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Discussion Starter #20
i found the bearing off the 302 where i got the crank. it reads:

D.A.B. 85
760 3 CAP-U
2-24
DA-49 3-24

Image48.jpg

can anyone tell me the bore? or if its regular?
 
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