Time for me to address the 800lb Gorilla in the room.(Engine knock thread) REVIVED!

[mcgovern61]

I finally got a chance to pull the right side cam out of the '81 engine and the wear is even, not lop-sided BUT... the cam lobes have a definate flat spot just passed TDC on the lobe on two of then and indendations on the back side of the lobes that I think would definately cause floating of the rockers after the lobe passes and then recontacts the rocker. I am very surprised otherwise at the good condition everything seems to be in considering the noise it made. The bearing journals on the cam shaft look great!

 

[scdmarx]

I just found this video about valve floating. To be honest, I'm more intrigued with the technology it took to produce this video than the actual content. :lust:
But this is what I meant about the flat spots on the cam lobes.

https://www.youtube.com/watch?v=_REQ1PUM0rY

 

[Tory]

Would the right 1200 cam have the fuel pump ddrive on it?Or can it be installed?

 

[joedrum]

yea your right ron on everything ...i guess i could have been clearer about the overlap its going to breath better and the higher the rpm it increases its breathing and thats where it will be better than the 1100 cam in the entire range that the cam grind is.....good stuff ron im going to read your link now :mrgreen:

no tory if you used 1200 cams you would have to go electric fuel pump and cover the hole with custom plate or something.....not a big deal realy ....there not completly inter changeable neither were the 1000s :mrgreen:

ron my whole assumption of 1200 cams in 1100 head is about better flow maybe ....the intake ports and exhast valve are bigger than 1200 heads ...there are a lot of reasons why honda makes decissions on products that has nothing to do with whats best for the motor and how it runs ....thats where opportunity is ....im not a numbers guy i work on hunches and maybes ......

that was a great read ron :mrgreen:

 

[dan filipi]

Impressive video Ron.
I haven't had a chance to read the link but I will.

Joe I think I'd be interested in a 1200 cam swap with you.
I would like to try the 1200 cam on the right first to see if the knocking is gone.
I'll have to set up a gravity fuel tank and pull the 1200 cam from the left side etc.
Gonna be a few days.

 

[dan filipi]

the cam lobes have a definate flat spot just passed TDC on the lobe on two of then and indendations on the back side of the lobes that I think would definately cause floating of the rockers after the lobe passes and then recontacts the rocker.

You described exactly what I see on the cam, looks like the follower floats after TDC then recontacts the cam on the other side as well as the indentations.

 

[joedrum]

dan you cant put the left cam in the right side stop!!!!!!!!!! :beg: :nea: oh2: :headscratch: :doh: :hihihi: :ahem: :mrgreen: it would not time right im sure not using the the marks anyway!!!! :mrgreen:

 

[dan filipi]

I don't think it would matter would it?

I'll have to have a look at a right and left cam.

 

[scdmarx]

I don't think it would matter would it?

I'll have to have a look at a right and left cam.

I'm thinking (ouch!) that due to the firing order: 1-3 and 2-4....
Both sides fire front cylinder first, then the rear cylinder. So it may just be a matter of "clocking" the other side 180* out. :?: But...I'm not there to look at it, so it's up to you to be sure.

 

[dan filipi]

I compared a right and left cam and the keyway is in the same place with the lobes pointing in the same direction so right and left cams are interchangeable.

There's something strange with the cam pulleys though.

In comparing the cams and keyways I also compared a pulley and found the timing marks look odd so it's got me wondering if my right side might be out of time.

On the pulley's there is a dot and a slash.

The left pulley I have on the bike right now doesn't have a stamped slash, it's a raised slash which clearly must be TDC because there's a tiny arrow pointing at it.
The slash doesn't line up with the dot on the other side of the loose pulley's but the dots do.
I've always used the slash as TDC ( I think, on the right pulley anyway) now I think I've been using the wrong mark when timing after looking at both sides of these pulley's.
Also one of the right pulley's on the shelf has a arrow pointing at the dot. This pulley also has a slash.

In this first photo the slash has been marked with a sharpie but that slash doesn't line up with the dot on the other side.
(Green's are dots, reds are slashes)

I'm confused but it is starting to look like I might have the right cam out of time.

It's probably on the right marks but I've got to open up that side now and check. Only way to be sure.

 

[joedrum]

i just did this the other day ...and after reading dans post im confussed to from lack of memory ....the slash and the lower arrow pointing to it is the mark ...the pulley is suppose to face with the slash and arrow facing out ....

let me say this again ...whatever mark on the pulley lines up with the lower arrow ....check the other pulley and use the marks that line up with arrow marks from the other ...gee this would be crazy if its off .....

ive watching that video ron put up several times its amazing how much movement the steel makes ...valve shafts bending ...valves boncing off the seat ...spinning and vibrating....its easy to see what kind of trama the wings are going through....but the valve trane on the wings is much better design than what was on the video ....look how old they are and still running with all the pounding going on ....

i dont care what the specs are its obvious to me that if these crude cut cams work for honda when new and were quiet its because the springs were good ....they anit good no more ....idont think there are springs to buy now new the only thing you can do is shim the springs to perload them ....and smooth the cams for the parts we have ....it would be nice to find springs that would work ....i bet some know where to get something who knows .....

so im going to work with what i got old parts and effort to make them work better :mrgreen:

 

[mcgovern61]

The last picture, where the arrow is pointing is correct. In the other pictures, the dots are correct, not the slashes. The dots are perpendicular with the key and the up mark and they are diaganol from each other (270 degrees and 90 degrees).

 

[joedrum]

did you get that info from your daughters gerry :ahem: :smilie_happy: :smilie_happy: :smilie_happy: :mrgreen:

 

[mcgovern61]

did you get that info from your daughters gerry :ahem: :smilie_happy: :smilie_happy: :smilie_happy: :mrgreen:

Always check with the experts!! (They have more wrench time on these motors than I do!) :smilie_happy:

(My 13 year old pointed out that the timing belt looks a little dry, could be time to change it in her opinion) :smilie_happy:

 

[joedrum]

okay its time for me to admit ive made some mistakes in memory in facts gathering and posting im used to it ....but im sorry for the transfiguration of my memory ill just list them and hope ive got it strait this time.... :headscratch:

there is no advantage to useing 1200 cams as an upgrade for the 1100 ....the overlap in cam timing is for a euro modle 1200 im sure was not sold in the us the overlap is the same as 1100 cams .....making the 1200 cams milder than the 1100s ....less power on top

even the 78-79 cams are milder than the 1100 cams there a lot like the 1200 cams

now i will try to say somthing real......the 1000 and 1100 heads with there solid arrangement are great heads with good flowing ports.....the problem is valve springs are the weakest link in the chain on these heads ......and sould be replaced often enough to keep the rockers on the cam .....

we dont have that option that i know of .....so it dosent matter what honda engineered grind for the cams are ....the rockers wont stay on it ....the speings are old and weak period ....the only way to fix this is to as ive said before is to smooth the cams out so there is lanching ramps in them .....and after that if the springs are working good or much better then i guy could shim the spring some as an added bump in the fixup :mrgreen:

 

[dan filipi]

Makes sense about the springs, the rockers and valves could be bouncing all over the place.

When I get out to my head shop I'll ask them about replacements.
They had new valves and guides and seemed to think there wouldn't ever be a problem supplying them.
Just a matter of cross referencing to something else.

 

[mcgovern61]

When I get out to my head shop I'll ask them about replacements.

Is it possible you could ask them what the actual shape of the cam lobes should have been when new? Seems that either the material used was not up to par, or their is an engineered design that these cam lobes are all wearing like this. I question, how did my number 1 valves get a sharp flat spot (almost like it was cut in like that) just past TDC on the lobe. I would have thought that it would wear down evenly. (The sharp flat spot runs across the lobe at just passed TDC, not like a wear mark that runs the length of the lobe.)

 

[dan filipi]

Will do Gerry. I see the same thing on at least one lobe of all the cams I have, including the 1000.
The 1200 cam is in good shape and does not have those edges and lumps. It's a smooth surface all the way around.

I'm also wondering about grinding these cams because on a couple lobes I see flaking like the hardened surface is coming loose.

The guys at this shop really know their stuff. If they tell me they can be filled, ground and hardened I'm sure they'll stand behind it.

 

[mcgovern61]

Will do Gerry. I see the same thing on at least one lobe of all the cams I have, including the 1000.
The 1200 cam is in good shape and does not have those edges and lumps. It's a smooth surface all the way around.

I'm also wondering about grinding these cams because on a couple lobes I see flaking like the hardened surface is coming loose.

Very interesting. I pulled the cams out of the right head on the old blown '82 engine. I know that it was run without oil and that was how the piston broke in two. The cam lobes are worn very much the same as the noisy '81 except they do not have that edge or lump but do have that pre and post dip before and after TDC. That engine only had 23k miles on it before it imlpoded. The '81 has somewhere around 169,000 miles or more that I can trace. Point is, is that dip cut into the lobes when new?

 

[dan filipi]

Will do Gerry. I see the same thing on at least one lobe of all the cams I have, including the 1000.
The 1200 cam is in good shape and does not have those edges and lumps. It's a smooth surface all the way around.

I'm also wondering about grinding these cams because on a couple lobes I see flaking like the hardened surface is coming loose.

Very interesting. I pulled the cams out of the right head on the old blown '82 engine. I know that it was run without oil and that was how the piston broke in two. The cam lobes are worn very much the same as the noisy '81 except they do not have that edge or lump but do have that pre and post dip before and after TDC. That engine only had 23k miles on it before it imlpoded. The '81 has somewhere around 169,000 miles or more that I can trace. Point is, is that dip cut into the lobes when new?

What I see odd on the cams also is after the follower passes over the top of the lobe and is heading down, the cam surface is "less worn" almost appears untouched by the follower. After this (I would call a "flat spot") in the cam the cam surface then has a polished (or worn) contact point.
These seems to suggest (to me anyway) that the follower is not contacting the cam continuously as it goes around then impacts the cam.
This is what I believe to be the knocking.
Very interesting thing going on here. I'll post a picture later today.