Engine Knock

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Joelpan
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Engine Knock

#1

Post by Joelpan » Sat Sep 25, 2010 5:17 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



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Re: Engine Knock

#2

Post by Hog54 » Sat Sep 25, 2010 5:47 pm

You should be running 8:1 not 10:1 with the crappy gas we have now.

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Re: Engine Knock

#3

Post by Bosheff » Sat Sep 25, 2010 6:32 pm

When you say "knock", are ya talkin bout "spark knock" or a knock in the engine when runnin?...bosheff

Joelpan
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Re: Engine Knock

#4

Post by Joelpan » Sat Sep 25, 2010 8:35 pm

It is a spark knock not a mechanical knock by a valve hitting or something. That's why I'm going to try 94 octane. I'm just about to do that now.

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Re: Engine Knock

#5

Post by NightShift » Sat Sep 25, 2010 9:24 pm

Dear JoelPan,

Welcome to the site and dont take the rest of this personal honest. We all went 10:1 once or a lot of us anyway. I did it when you still could.

The real problem was whatever made the valve stick but thats gone with the rebuild we hope huh. (What could the oil pump do so wrong?)

And your knock is a clackclackclack as you leave a stopsign, right?
Or it is all the time even sitting at the stop?
Even cruising?

Since you are new here you really really might want to search all the valve adjustment threads (like "aluminum pushrods") because that might go a long ways to quiet things up. You gotta have a rad cam with compression like that.

No matter what you want to retard your timing to the front of the hole til its almost out of sight.
And get rid of every bit of extra weight and any windshield and make your date drive her herself.

And pray its really 94 octane yeah right.

The motors together so get what miles you can out of your money! No point in spending it twice.

Sincerely,

Joelpan
Posts: 26
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1977 Ironhead Sportster
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Re: Engine Knock

#6

Post by Joelpan » Sun Sep 26, 2010 2:47 pm

It seems as though I was wrong about the cause of the knock. It is a mechnanical knock after all. The rear intake pushrod was not seated properly in the rocker. This caused the knocking sound. As far as running 10:1 pistons, I have used them since I first rebuilt the motor about 30 years ago. The bike has always run great like this. I have not road tested yet the knock started when I finally got it running. This thing fought me the hole way this time. To many problems to list. Anyway I think I have it solved now and with any luck I will road test today weather pending. Thanks for all the input. I will let you know how it turns out.

Joelpan
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1977 Ironhead Sportster
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Re: Engine Knock

#7

Post by Joelpan » Sat Oct 02, 2010 1:45 pm

Now I'm really att a loss. The noise is coming from the rear intake valve. When the pushrod reaches its highest point the valve clicks. Actually I think its just after the highest point. I can see the pushrod jump a bit for lack of a better term. The valve is not rotating either. I have removed the head and taken out the intake valve. The only thing I see wrong is a badly chewed up guide. I don't know how I missed it when I had it apart before. Anyway I don't know why it clicks. I think its sticking for just a split seecond at the top but I'm not sure. I'm replacing the guide & valve and can only hope that does it. If anyone has any other ideas as to why it clicks I'm all ears so to speak. This is a mind boggler.

Later
Joelpan

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Re: Engine Knock

#8

Post by john HD » Sat Oct 02, 2010 1:53 pm

how does the tip of the rocker look?

john

Joelpan
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Re: Engine Knock

#9

Post by Joelpan » Sat Oct 02, 2010 2:31 pm

Funny you should ask. There is a mark on it from hitting the valve. It should polish out but it shouldn't be there since the rockers are new.

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Re: Engine Knock

#10

Post by kitabel » Sat Oct 02, 2010 2:49 pm

Have a nice day.
Last edited by kitabel on Sun Oct 03, 2010 2:30 pm, edited 1 time in total.

Joelpan
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Re: Engine Knock

#11

Post by Joelpan » Sat Oct 02, 2010 2:58 pm

My rocker assemblies are brand new. They can't possibly be worn already. I will check though.

Joel

JR JOHNSON
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Re: Engine Knock

#12

Post by JR JOHNSON » Sat Oct 02, 2010 3:24 pm

ONE THING TO LOOK AT ON AFTERMARKET TAWNEES STUFF IS TO CHECK WHERE THE ROCKER TIP HITS THE VALVE,SHOULD BE RITE IN THE CENTER OF THE STEM. IF ITS OFF CENTER,ITS GOING WEAR YOUR VALVE TRAIN TO HELL, BEEN THERE,DONE THAT. FINE SOME OEM ROCKERS,BLOCKS. I BELEAVE THAT BAISLEYS IN PORTLAND OR. RESTORE THE OLD ONES, JUNK THE NEW CHINA ONES. THEY ALLSO SAID THE BEARING STUFF IN THE AFTERMARKET STUFF IS TO SOFT, HOPE THIS INFO HELP YA WITH RESPECT JR ALSO IT WAS NOISEY,THEN NORMAL. THERE JUNK, BEEN THER DONE THAT! JR

Joelpan
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Re: Engine Knock

#13

Post by Joelpan » Sat Oct 02, 2010 3:50 pm

Hi JR: Shouldn't the rocker be off center just a bit and this is what makes the valve rotate as it goes up and down. The new set of rocker assemblies were made in the good old USA. At least that's what it says. The guy I get my parts from is not too hip on the China junk. I will check to see how close to center it is hitting. Thanks for the input.

Joel

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Re: Engine Knock

#14

Post by JR JOHNSON » Sat Oct 02, 2010 4:24 pm

HI, TO ME SHOULD BE PRETTY CLOSE IN THE CENTER,UNLESS YOUR VALVE IS IN DEEP, I MY BE WRONG,BUT THE ROCKER WAS'NT DESIGNE TO ROTATE, THE VALVE FLAT,ROCKER FLAT, IT MAY TURN BEING PUSHED DOWN,I DON'T THINK SO,THEY RUN ROLLER TIP ROCKER ON PANS, SO ITS NOT PULLING THE VALVE TO ONE SIDE,OR OTHER, SOME BODY MIGHT CORRECT ON THAT. ARE THE ROCKERS HAVE ALLUM BLOCKS, OR A SHINNY BRASS LOOKING? IF YOU HAVE YOUR OLDS,MACH THEM UP,SET THE ROCKER ON THE HEAD,SEE WERE THE STOCK ONE HITS, AND SEE HOW DEEP YOUR VALVES IS,MINE WAS HITTING THE PAN,THEN MADE MISTAKE PUTTING IN VALVE SEATS. I'M PROBLEY NOT NO HELP TO YOU, BUT I'LL TRY MY BEST. I'VE BROKEN ALOT STUFF OVER THE YEARS,I'VE LEARN THE HARD WAY, WITH RESPECT JR

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Re: Engine Knock

#15

Post by Bigincher » Sat Oct 02, 2010 4:33 pm

JR JOHNSON wrote:HI, TO ME SHOULD BE PRETTY CLOSE IN THE CENTER,UNLESS YOUR VALVE IS IN DEEP, I MY BE WRONG,BUT THE ROCKER WAS'NT DESIGNE TO ROTATE, THE VALVE FLAT,ROCKER FLAT, IT MAY TURN BEING PUSHED DOWN,I DON'T THINK SO,THEY RUN ROLLER TIP ROCKER ON PANS, SO ITS NOT PULLING THE VALVE TO ONE SIDE,OR OTHER, SOME BODY MIGHT CORRECT ON THAT. ARE THE ROCKERS HAVE ALLUM BLOCKS, OR A SHINNY BRASS LOOKING? IF YOU HAVE YOUR OLDS,MACH THEM UP,SET THE ROCKER ON THE HEAD,SEE WERE THE STOCK ONE HITS, AND SEE HOW DEEP YOUR VALVES IS,MINE WAS HITTING THE PAN,THEN MADE MISTAKE PUTTING IN VALVE SEATS. I'M PROBLEY NOT NO HELP TO YOU, BUT I'LL TRY MY BEST. I'VE BROKEN ALOT STUFF OVER THE YEARS,I'VE LEARN THE HARD WAY, WITH RESPECT JR
JR, can you please tell me more about your 'mistake' of putting in valve seats? I recently had my heads rebuilt, and the guy cut out the old seats and installed new ones. (groan) Also new valves, springs, etc.... Also new valve rockers. Now I can't get the pushrods in. I was so pissed off about this that I just quit working on the motor for awhile.
I notice also that the end on the rocker shaft does not contact the top of the valve stem very well. Looks like some dressing of the rocker would be in order. Is this common? I may have to start a new thread here, don't want to hijack this one...

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