Engine Knock

Forum rules
Please do not start new topics here, but here: New Panhead and Flathead topics
Post Reply
Joelpan
Posts: 26
Joined: Sat Sep 25, 2010 3:58 pm
Bikes: 1956 Panhead
1977 Ironhead Sportster
Location: Niagara Falls, Canada

Engine Knock

#1

Post by Joelpan » Sat Sep 25, 2010 5:25 pm

Hi Everyone:
I recently had a disater with my 56 panhead. A tappet roller exploded caused by a sticking valve. I ended up replacing all the tappets, tappet blocks, camshaft and oil pump. I also replaced exhaust valves and guides and lapped all 4 valves. The cam I installed is an Andrews J grind. I have 10:1 pistons running an S&S Super B carb. The bike starts great but I have a very distinct knock now. Has anyone ever expeienced this and if so how did you solve it. I'm currently running regular gas 87 octane and was going to try 94 octane instead. If anyone has any input I would greatly appreciate it. By the way I'm new to this site so greatings to all.

Joelpan



58flh
Posts: 3339
Joined: Sat Jun 26, 2010 1:54 pm
Bikes: 1958flh 1969sporty,had a knuckle but sold back to original owner
Location: NEW JERSEY
Has thanked: 195 times
Been thanked: 259 times

Re: Engine Knock

#2

Post by 58flh » Sat Oct 09, 2010 2:38 pm

Joelpan wrote:Hi Everyone:
I recently had a disater with my 56 panhead. A tappet roller exploded caused by a sticking valve. I ended up replacing all the tappets, tappet blocks, camshaft and oil pump. I also replaced exhaust valves and guides and lapped all 4 valves. The cam I installed is an Andrews J grind. I have 10:1 pistons running an S&S Super B carb. The bike starts great but I have a very distinct knock now. Has anyone ever expeienced this and if so how did you solve it. I'm currently running regular gas 87 octane and was going to try 94 octane instead. If anyone has any input I would greatly appreciate it. By the way I'm new to this site so greatings to all.

Joelpan
How are you joelpan/ I can understand the knock with the fuel you use & comp. your running,my ? is did you have this comp. before & did it knock then? If this is all new do to the rebuild of top-end-then octane her up & see how she responds. If it still knocks but sounds like it got a little lower,check your timing. Another ? is does it knock more under a load-like when you twist the wick hard,if so it could def. be a octane-comp.ratio,timing thing.What scarey is you blew that roller,ahunk gets to the bottom-end,lots of things NOT-GOOD will happen,like mainbering,crankpin damage etc. Besides whoever did the job im sure checked it out very well,i hope! & if you did the work yourself then you have to be experienced & I know you wouldnt let a thing like that slip-by! One more thing it could be is a bent rod,but going to a higher compression piston this you would have checked firstoff! So it sounds like she needs some juice to me & do a few minor checks.Are you running a stroker 96 or better? cause the 10 to 1 pistons really dont give you much more then a hard kick,8 or 9 to 1 if checked on a dyno will be right in the same ballpark horsewise on a stock 74, but if your stroked-out then by all means I would do the same! Hope my little imput answered any ?s you may have & good-luck sounds like a nice machine!!!!

Joelpan
Posts: 26
Joined: Sat Sep 25, 2010 3:58 pm
Bikes: 1956 Panhead
1977 Ironhead Sportster
Location: Niagara Falls, Canada

Re: Engine Knock

#3

Post by Joelpan » Tue Oct 12, 2010 12:23 pm

Well I've taken care of the top end knocks. For some reason my intake valves started sticking. Not really sure why. Have a few ideas and hopefully it won't happen again. Now there is a knock in the bottom. When I put the stethoscope to it I would say its in the gearcase down near the bottom. The thing is everytime I start it the sound gets worse. It's like something is coming apart. The only thing I can think of is the pinion shaft nut. This nut is designed to get tighter as it runs with the left hand thread. I will say that whatever it is will jump out and bite me in the ass as soon as I take the timing cover off. Unfortunately it will have to wait. I've got too many other things that need taking care of before old man winter sets in. I appreciate all the input and if anyone has any thoughts as to what else could knock behind the timing cover feel free to let me know. I will definately let you know what I find once I get back at it.

steinauge
Posts: 521
Joined: Tue Feb 03, 2009 10:05 pm
Bikes: 1938U,1949FL,1961FL,1968XL,1979FL ,1958 FL, 1965 BMW,1975 Honda CB750
Been thanked: 9 times

Re: Engine Knock

#4

Post by steinauge » Tue Oct 12, 2010 7:05 pm

If you lost a tappet roller you have an engine and an oil tank full of metal. :( We used to refuse to warranty any repairs in that situation unless the customer was willing to authorize a complete teardown because that was the only way to be sure we got it all.

JR JOHNSON
Posts: 325
Joined: Thu Jan 07, 2010 5:13 pm
Bikes: 1941wla,1946el,1947fl,1950fl,1959flh,1972flh,4 twinkies,1 evo
Location: oregon
Has thanked: 4 times
Been thanked: 11 times

Re: Engine Knock

#5

Post by JR JOHNSON » Tue Oct 12, 2010 7:49 pm

hi, my question is if you put an andrews cam in it,and do you have a bronze bushing in the case? my 50 i'd put an andrews b grind in it, but the shaft was .001 bigger than stock, just fit in the bushing,i'd not like that, so had ground down to the stock size. i'm not sure if the needle type bearing is differant size shaft in it. i'd bought it at a swap meet,did'nt call andrews.
to be honest with you,i was worryed about the bearing seezing on the camshaft,spinning the bearing in the case. but i'm sure this is not your probs,but something that people need to watch out for....with respect...JR

Joelpan
Posts: 26
Joined: Sat Sep 25, 2010 3:58 pm
Bikes: 1956 Panhead
1977 Ironhead Sportster
Location: Niagara Falls, Canada

Re: Engine Knock

#6

Post by Joelpan » Wed Oct 13, 2010 12:13 pm

Hi Steinauge: What you say about a complete tear down is exactly what I thought when the problem 1st occured. Unfortunately I let a harley mechanic friend convince me it wasn't necessary. I should have gone with my gut. It's coming apart now, I just hope I havn't done to much damage already. At least now I know it will be done right. Thanks for the input.

Joelpan

Post Reply

Return to “Motor”