Topic: damn 'F' model

[superchode]

guess the engine ailment:

http://www.3cpu.org/gallery/750_repair/750_head%20aug08.jpg?size=orig

[eurban]

Top end oil starvation on the 1-2 side.

[bwaller]

a certain little blocked restrictor.

[superchode]

eurban's the winner! not even 10 minutes... nicely done.

now to fix it.  still torn between fixing the F head up (valve guides and seats have been done) and replacing the top end with a K head.

[SD750F]

Concerning the restrictor. My 1978 F3 engine has one installed on one side while the other side has no restrictor. Tell me should I have the one removed or the other installed??? I have been looking through my maintenance books and can not find anything about it.

I should add that I have APE HD studs that will restrict the delivery of oil to the top end because of the wider diameter in the supply path. So I want to make sure that I will provide enough oil to the top end without flooding. I would imagine this is the reason for the restrictor(s) in the first place to balance the entire oil delivery system?

Scott

[NWrider]

Can you directly replace an F head with a K head? I was under the impression they were different enought that they didn't interchange directly due to oiling or draining differences. I'm have the understanding the pistons will have to be replaced as well.

If there is a change over, I'd sure like to understand what it takes, assuming I don't have the correct info.

[WFO]

Iam going to say it's missing the cover to keep all that oil in there 

[fixahonda]

Wow! That valve gear looks like it got hot!

I've never seen the "F" problem before. Good luck sorting it out.

[Bodain]

Can you directly replace an F head with a K head? I was under the impression they were different enought that they didn't interchange directly due to oiling or draining differences. I'm have the understanding the pistons will have to be replaced as well.

If there is a change over, I'd sure like to understand what it takes, assuming I don't have the correct info.

You can. It will fit, but you will have more grief than you can shake a stick at. There are draining differences.
If you go K. You must do Pistons, Cylinders, and Head.

[Terry in Australia]

That's it guys, you need to do a whole "Top End" rebuild, not just the head. If it's just an oiling problem though, the K head won't fix it, they have the same issues.

Shortly I'll be posting pics of my new external "Top end Oiler" kit that takes oil from one of my oil cooler adapters, and sprays it onto the exhaust side of the cam, (the hottest side) so with one of these installed, you'll have a lot less to worry about it happening again. Cheers, Terry.

[eurban]

Wow! That valve gear looks like it got hot!

I've never seen the "F" problem before. Good luck sorting it out.

No this is not the "F" problem.  That would be valve guide wear, largely due to valve angle.

[Jerry Rxman Griffin aka MuthaF'er]

Don't you be cursing our beloved F models (at least the ORIGINAL F's)

[superchode]

ok, ok, i take it all back.

i do have a question about the oil orifices, though... the manual says to remove oil o-rings and orifices after removing the cam towers.  can you actually get the orifices out at this stage (ie. without taking the whole head off)?  i can't see if or how they are removable.

amazing what a contrast there is between the left and right sides of this engine.  one side was being oiled perfectly while the other was tying out and heating up.  both orifices look identically clean, though.  i'd love to get them loose and have a real good look.

[05c50]

When I rebuilt the top end on my 750a, I was able to get the restrictors out after removing the towers.
 I have a couple of questions. Do you have any idea how long the engine ran in this condition (hours,miles)? Did you recently have the engine apart? It seems that most of cams that wear like this are caused by gasket sealer getting into the restrictors. I'm just wondering out loud-what would cause your restrictor to plug up?

.........Paul

[superchode]

so i should be able to just grab the restrictor (with the head still on) and pull it out?

motor was rebuilt fairly recently... i didn't use any gasket sealer, though... just the gaskets themselves.  something got in there, i'd expect.  have to get that restrictor out to find out.

[05c50]

It's been a few months since I did the engine, but I'm pretty sure that I used a sharp pick and pulled the o ring and restrictor out after removing cam baskets. Let us know what you find plugging up the hole.

........Paul

[superchode]

ok, pulled them out.

oddly enough, the well oiled side didn't look much different from the un-oiled side.

definately small bits of something in both orifices.  the side that cooked happened to get the main passageway blocked.  should work fine now, too bad i'll need another set of towers and a camshaft. one or two of the hot rockers should be replaced as well.

[05c50]

If it were mine, I'd try to flush  out the oil passages and maybe pull the pan to clean out any debris before I replaced any parts. Just a thought.

.......Paul

[MRieck]

You have make absolutely sure those upper case oil feed holes are clear....another member recently had a problem with that.

[joeb]

I am running a K head on my 78 836 and to keep the oil from pooling in the head area I had a valley cut on the bottom of the cylinder to connect the oil drain hole that is blocked off by honda to allow the oil to drain faster from the head.

[SD750F]

Well I am getting the idea without hearing it specifically that you should remove the restrictor(s) in the top end oil gallery on a "F" engine? Is that correct?

What do you think Terry? Anyone else? I am at the point with my rebuild were it is the perfect time to do the right thing.

Scott

(see my question early in the thread)

[Jerry Rxman Griffin aka MuthaF'er]

Definitely not. The only real issue with a F head is only with the 77/78 F and it pertains to valve guide wear. This is due to the more "extreme" valve angle relative to the cam (as compared to the original head used on all other including 75/76 F's) and the ensueing additional stress causing the guides to wear prematurely.

[bwaller]

Definitely not. The only real issue with a F head is only with the 77/78 F and it pertains to valve guide wear. This is due to the more "extreme" valve angle relative to the cam (as compared to the original head used on all other including 75/76 F's) and the ensueing additional stress causing the guides to wear prematurely.
[/quote

+1.   Most definitely not. Again, the restrictors are there to maintain adequate oil pressure to the crank and bottom end. I wouldn't even consider enlarging them.

The restrictor size is adequate. Obviously the problem is that people are not meticulous enough when rebuilding if these are blocking with any kind of crap. Sorry but lets be honest. If there was no restrictor the rest of the passageways upstream are small enough to be blocked with the same crap anyway.

Terry's plan, I believe, is to just add a little extra.

[bryanj]

Been there, seen the video, shrunk the Tee shirt.

Most common cause--------

lumps of old cleaned off gasket falling into oil pathways

[Terry in Australia]

What Bryan said, very common that the "blockage" was introduced by either a "bodger" slopping silastic over old gaskets, or a well meaning rebuilder leaving a few gasket scrapings in the cases.

My "TOE" is intended as an "enhancement" to the OEM oiling system, and definitely not as a replacement. It's been speculated in another thread that the OEM jets (restrictors) could be removed or "bored out", but I wouldn't attempt it, the person who suggested it certainly hasn't tried it either........... Cheers, Terry.