knocking noise 8ba

allen

allen

Well-known member
Hi guys built many Flatheads all ran very nice never had one give me this much trouble, First lets start with everything is new 4 inch crank, all valves are new and springs cam bearing ever thing, the knock is odd at idle you hear it in the front when rev you hear in the rear not the oil pan but in the bell housing, the crank was taken back out and double double check new bearing again installed look over ever thing saw no marks at all looked great. once again install ever thing fire her up and its still there, all rod and pistons were checked by me and the machine shop, think it might be the cam can the cam thrust back and fourth causing a knock, the cam gear has been replace with a aluminum then fiber. the oil pump replace twice with new ones the lifters are adjustable all settings has been check and check set at 13 and 15, thanks for any ideas AL also oil presurre is great idle 30 high rev 50 psi
 
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Sounds about like the trouble I had,I isolated it to one cyl by un hooking one plug wire at a time, no 7 wrist pin was loose,repaired it and all was smooth.
 
Hi Allen; You could try running the engine with a timing light hooked up and see if the light jumps around with the knock. Also what engine do you have and was it balanced? Good luck, Craig.
 
Don said:
Sounds about like the trouble I had,I isolated it to one cyl by un hooking one plug wire at a time, no 7 wrist pin was loose,repaired it and all was smooth.
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Thanks for the info Don, did check the wrist pins all new with wrist pin bushings and did un plug the plug noise stayed the same
 
Craig CT said:
Hi Allen; You could try running the engine with a timing light hooked up and see if the light jumps around with the knock. Also what engine do you have and was it balanced? Good luck, Craig.
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Have not tried this what would this tell, thanks for the help craig also did not have this balanced the noise does not seem to be coming from the oil pan took a hose and listen you and hear it clear when the hose is next to the rear of motor right at the bellhousing took the flywheel off and replace with a second one and change the idle gear out too,
 
allen said:
Have not tried this what would this tell, thanks for the help craig
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Hi Allen; Could indicate if cam is moving back and forth showing gap for thrust is too much. Good luck, Craig. PS What engine is it?
 
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allen said:
Sorry Craig it is a 8ba with merc crank should be 255 bore 60
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Hi Allen; You probably know with the later post distributor the thurst is towards the front. In your first post you mentioned there was noise at the front and the back, so cam movement was the first thing that came to my mind. In JWL's book "Flathead Facts" he says cam thrust gap is one of the things some of us forget to check. Good luck, Craig.
 
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If they are EGGE pistons, Walt is probably correct. I could not use EAB heads because the EGGE pistons set a little higher in the bore.
 
yes if their egge pistons that will be the trouble they have a higher dome than the originals so many people have had this problem with the egge pistons im just going through the same three pitons to high, this seems to happen only with the 4" crank for some reason ,you need to use little silver paper balls to check the hight best of luck.... however a friend of mine just had a funny knock from front of engine he took the new gears off and replaced with another set bingo no knock anymore
 
Jack 34pu said:
If they are EGGE pistons, Walt is probably correct. I could not use EAB heads because the EGGE pistons set a little higher in the bore.
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Im running EAB heads pistons were from reds header will check and see if they were Egge but when tore down for the second time there was no marks at all on the pistons thank for this idea
 
I had one a couple of yr's ago, EAB heads, one pistons was just baily hitting the head in the middle, took a die grinder and ground down the spot in the head, the guy has 20 grand on the engine and never any trouble. Walt
 
Thanks guys for all the help yes they are egge piston got back two years ago, called Jim at reds headers he knows of this said the newer ones will not do this Egge is the only one that makes this for the 255 so there you go, any way going to run other heads either 8ba or edbrock thanks everyone for all the help AL
 
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