New engine, Knocking?

J

JWadeSchutt

New Member

Nov 18, 2006

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May 6, 2007

#1

• May 6, 2007

• #1

I just rebuilt my 82 with the mods listed below and i have about 100 miles on it so far but it has a knocking sound really bad when it is under load, it doesn't do it when in neutral. i have heard about piston slap with forged pistons because they expand, but do you think this is it, i dont want to be driving it around too much with something wrong.

 

T

Twisted306

New Member

May 6, 2007

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May 6, 2007

#2

• May 6, 2007

• #2

dose it sound like a rod knocking or a rocker knock

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

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B.C. Canada

May 6, 2007

#3

• May 6, 2007

• #3

Can you get the sound recorded for us to listen to? What were your bearing tolerences? Did you plastic gauge evrything to make sure it was within spec?

 

J

JWadeSchutt

New Member

Nov 18, 2006

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May 7, 2007

#4

• May 7, 2007

• #4

yes all of it was plastiguaged

 

J

JWadeSchutt

New Member

Nov 18, 2006

27

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1

May 7, 2007

#5

• May 7, 2007

• #5

its not really like a ticking but more of a deep knock and i can hear 4 of them in a row.

 

J

JWadeSchutt

New Member

Nov 18, 2006

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May 7, 2007

#6

• May 7, 2007

• #6

its like maybe one bank of them are doing it could it be firing order or bad wires?

 

8

86bluecobra

Advanced Member

Dec 20, 2004

4,265

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69

B.C. Canada

May 7, 2007

#7

• May 7, 2007

• #7

It could be an exhaust leak???

 

cobradvm

New Member

Sep 2, 2003

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Woodinville, WA

May 7, 2007

#8

• May 7, 2007

• #8

86bluecobra said:

It could be an exhaust leak???

Click to expand...

x2 - you may just have a leak at the header - try pulling plug wires one at a time, and see if you can isolate it to one cylinder. I had an exhaust leak, and I was convinced it was something seriously wrong - a real metal on metal sound - turned out to be a crappy BBK header gasket.

 

J

JWadeSchutt

New Member

Nov 18, 2006

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May 15, 2007

#9

• May 15, 2007

• #9

ok so i have an update. i found that the noise was exhaust leak and backfiring. i went ahead and got new coil modulator and checked the plugs and got new cap and rotor. however i am still having the same problem still. i just figured that it was an electrical misfire and the old modulator was the problem. any suggestions now?

 

302RollinHard

New Member

Sep 26, 2005

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0

Columbus, OH

May 15, 2007

#10

• May 15, 2007

• #10

Simple things first.
make sure you have the plug wires on right.
and make sure the flange surface on the header is flat. If it isn't likely you will get the thing to seal up.

 

J

JWadeSchutt

New Member

Nov 18, 2006

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May 17, 2007

#11

• May 17, 2007

• #11

k well the wires are right and the mani is sealed up nice. but still backfire.

 

Paul Perreca

New Member

Mar 30, 2005

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May 17, 2007

#12

• May 17, 2007

• #12

check your timing - make sure its not way off because my timing was WAY off and i had that same type of noise under "heavy load" as soon as i adjusted the timing correctly it was gone and less embarressing - this was also after a fresh rebuild

 

J

JWadeSchutt

New Member

Nov 18, 2006

27

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1

May 18, 2007

#13

• May 18, 2007

• #13

today after taking some thing apart i find collapsed lifters and possibly a flat cam. what could cause this? i called the company and the springs are right for the cam. but im not sure if they are trying to get out of buying me a new cam. everytime it is cranked there is soo much pressure that the lifters fall back down after a couple seconds.

 

K

krallman

New Member

Mar 3, 2006

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Hurricane, WV

May 18, 2007

#14

• May 18, 2007

• #14

you could have wiped out a cam lobe. Did you break in the cam properly. What type of cam are you running. I hear comp cams are bad about it if you dont break it in to a t.

 

J

JWadeSchutt

New Member

Nov 18, 2006

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May 18, 2007

#15

• May 18, 2007

• #15

its a lunati cam .522 int. .538 ex. i ran it exactly how the directions from the manufacturers notes said. the problem is that the performance shop i went to gave me too strong of springs and i think thats what caused it. but to cover themselves they are saying that the oil i used made the cam go flat. whats up with that? is this something that is true or am i getting fed full of BS?

 

I

izzleon

New Member

May 7, 2007

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May 19, 2007

#16

• May 19, 2007

• #16

prime

did u prime the engine before starting it? what type of valve train u using?

 

J

JWadeSchutt

New Member

Nov 18, 2006

27

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May 20, 2007

#17

• May 20, 2007

• #17

ya i primed it just before startup. lunati cam, stock rockers, comp magnum pushrods, lunati lifters, comp springs, comp timing chain