valve and guide clarification

[LOUD MOUSE]

You must be changing the valves as the guides were good when I shipped the head.
I see the 250 guides are shorter than the 305 I have on my desk. ................lm

They were very loose on the new valves I put in.

G

OK.
What was wrong with the guides?. ..............lm

I use a butane gas torch to heat up the head.

G

What caused the HEAT RING?. ................lm

Dick

Yes - I guess that the earlier valves would have been all stainless. Not so good as a bearing material in the guide but better for the head in contact with hot gases.

I understand your feelings fro driving out the guides but the aluminum will expand more than the cast iron guide so will release the interference a little.

Here is a picture of the tool I made to knock my guides out and the guides themselves.

G

Dick

I got my head cleaned up first and then pushed the guides out from the inside. Pretty difficult to get those circlips off when they are still in the head.

As for the valve, I would think it was a cost-saving measure. Austenitic stainless for the head and a cheaper alternative for the stem. Probably friction-welded together.

G

Thanks, Graham.
From stated above, the earlier exhaust valves were entirely stainless?
As for the guides, I noticed I could get some movement on one of the guides when I had heated the head up to remove the cams, but my objective at the time was cam removal, not guides. BTW, the cams came out very easily after heating the head in the oven @ 250 deg for about 45 minutes - I do not like driving parts out of interference fits. I did mic the cam bearings, and set a bore gage to that diameter, and measured the cam bearing bores: they were .0003" larger than the bearings. Honda cast a clearance at the 12 o'clock position in the cam bearing bores, and I would presume that when the head is torqued down, the bearing bores close minutely to lock the bearings down.
I'm going to turn up a piloted driver for the guides [7mm pilot], and warm the head up again, and try removal. I do have some pitting on the combustion side of the guides, and my primary concern is scoring the guide bores - I'll have to go gingerly to avoid that.

[G-Man]

Dick

You just have to remember that the tool has to go through the guide bore, too. You need to make it a smaller diameter than the O/D of the guide but a reasonable fit on the 7mm dimater to keep it central.

I haven't found many of these guides to be worn but the ones on my '61 project were looser than I like and made it difficult to centralise my Neway cutters.

G

Dick

Yes - I guess that the earlier valves would have been all stainless. Not so good as a bearing material in the guide but better for the head in contact with hot gases.

I understand your feelings fro driving out the guides but the aluminum will expand more than the cast iron guide so will release the interference a little.

Here is a picture of the tool I made to knock my guides out and the guides themselves.

G
Thanks, Graham.
That tool is what I have in mind - piloted brass. The pics of the guides are helpful - thanks!

[LOUD MOUSE]

I see you are building a FULL RACE ENGINE.
As there are many folks watching a series of discussion like this one and I see replacing things which I seldom see needing replacement
I ask WHY so others don't think "I have to do that"when they work on their engines/bikes.
I remove the cam bearings by placing them in the jaw of my vise wide enough for the lobe to clear but the sides of the inside race rests on both jaws. BLAM.
I don't use any other valves other than HONDA as when I rebuild heads I make them HONDA STOCK.
I build engines to be easy starting, run like HONDA intended, able to ride for miles at a time with usually nothing more than points adjustment and cam chain adjustment.
I see in your case you are building for POWER now that you have described ALL the PARTS you are CHANGING.
Are you building a VINTAGE RACE ENGINE?. ...............lm

Hello Dick.
I have a couple of questions about the guides and cam bearings.
What was the reason to replace the guides?
The wire Cir Clip is a limiter to stop the depth of the guide to an exact depth as the guide is installed from the top.
I've found "2" bad guides in all the heads I've rebuilt.
Both were intake and both had cracked in halt at the lower groove made to allow air to inter when the valve opens. (not much air and after time HONDA removed that from the guide/head.)
All the actual HONDA valves I have are the same as to magnetism. (I have plenty here and they usually have a "B" cast on the head but not all the exhaust but most do have the "B".
All of the intake is steel which is drawn to the magnet.
All of the exhaust will not draw to the magnet.
Beware of the CHEAP after market valves on eBay.
HONDA shows using a piece of wood and rubber mallet to drive the cams out.
I use Brass or Aluminum rod.
Did the 250 degree heat ruin the neoprene on the advance weights?
Do you think there may be a possibility that the steel dome may come loose if the head is heated several times? (I've had 2 leakers and I hadn't heated either of them.)
. ....................lm

Thanks, lm
I am considering making new valve guides from SAE no. 62 hard bronze - an excellent material for severe use. The ends of my guides are pitted, and I am concerned with carbon build up around the stem.
All of my exhaust valves with a "B" are entirely non-magnetic - is that your preference, lm?
250 degrees is only 38 deg above boiling, hot enough for the aluminum to expand, and less than the operating temps of the head. I put a couple of pennies on the point cam under my vise grip jaws to protect it, and the cam came out with little effort. The same for the opposite cam. The cam bearings are a press fit on the cam, and I have always been hesitant driving bearings out, whereby the races and balls take the shock load.
As for the neoprene on the advancer weights, they do not seem to be affected; besides, I am using the Sasche-Elektronic crank-mounted ignition, and removed the weights and point cam from the camshaft, and will cover that end with a cl77 cam end cover. I cut off the tach drive from the l.h. cam, counter bored the end, and made a tool steel washer to fit the counter bore. I shortened the expander bolt, re-threaded it, and made all to fit under a cl77 l.h. cam end cover. BTW, the weight of the stock points system parts I removed was 269 grams [ about 9.5 oz ].

[DianneB]

..... building a VINTAGE RACE ENGINE?

Hummmm, what an interesting idea! Was wondering what to do with my CB160 ;)

[LOUD MOUSE]

I'm sure others have an idea that I support STOCK HONDA BIKES all the way.
Were I you I'd build what I wanted at the time.
That said I have and sell some HONDA 250/305 Competition cams (used) and springs.
I actually have a oversize (I think I have a used 350 cylinder and gasket set) that I will sell for a reasonable price.
Not perfect but in my opinion usable. .......................lm.

..... building a VINTAGE RACE ENGINE?

Hummmm, what an interesting idea! Was wondering what to do with my CB160 ;)

[Dick Eastman]

I see you are building a FULL RACE ENGINE.
As there are many folks watching a series of discussion like this one and I see replacing things which I seldom see needing replacement
I ask WHY so others don't think "I have to do that"when they work on their engines/bikes.
I remove the cam bearings by placing them in the jaw of my vise wide enough for the lobe to clear but the sides of the inside race rests on both jaws. BLAM.
I don't use any other valves other than HONDA as when I rebuild heads I make them HONDA STOCK.
I build engines to be easy starting, run like HONDA intended, able to ride for miles at a time with usually nothing more than points adjustment and cam chain adjustment.
I see in your case you are building for POWER now that you have described ALL the PARTS you are CHANGING.
Are you building a VINTAGE RACE ENGINE?. ...............lm

I don't know that it will be a "full race engine", but some things mfr's do are more cost-effective, much to the chagrin of designers and engineers. No doubt a crank-mounted ignition will be more precise than the stock system, and why I am eliminating a half pound of unnecessary rotating mass. I've generally found a little "tweaking" here and there can improve performance and reliability. Besides, I love internal combustion engines, from my model airplane engine collection , to the big block Chevy in my garage [it's not in anything, but I really had fun building it, and am trying to convince my wife to let me set it in the living room with a glass top as a coffee table].
In my opinion, the 305 engine was one of the most aesthetically beautiful engines Honda ever produced, but Honda's casting and manufacturing capability was not then what it is today - hence a few "tweaks" here and there. As a retired toolmaker, I can't leave well-enough alone, and my Super Hawk is going to look some what like a vintage track bike. I have another that will go back to show room stock.
A couple of pics of my 1961 Chevy 348 [first big block], starting with a "before" pic. I had a '61 Impala SS in '68, with the 3x2 set-up - always liked that engine.

Hello Dick.
I have a couple of questions about the guides and cam bearings.
What was the reason to replace the guides?
The wire Cir Clip is a limiter to stop the depth of the guide to an exact depth as the guide is installed from the top.
I've found "2" bad guides in all the heads I've rebuilt.
Both were intake and both had cracked in halt at the lower groove made to allow air to inter when the valve opens. (not much air and after time HONDA removed that from the guide/head.)
All the actual HONDA valves I have are the same as to magnetism. (I have plenty here and they usually have a "B" cast on the head but not all the exhaust but most do have the "B".
All of the intake is steel which is drawn to the magnet.
All of the exhaust will not draw to the magnet.
Beware of the CHEAP after market valves on eBay.
HONDA shows using a piece of wood and rubber mallet to drive the cams out.
I use Brass or Aluminum rod.
Did the 250 degree heat ruin the neoprene on the advance weights?
Do you think there may be a possibility that the steel dome may come loose if the head is heated several times? (I've had 2 leakers and I hadn't heated either of them.)
. ....................lm

Thanks, lm
I am considering making new valve guides from SAE no. 62 hard bronze - an excellent material for severe use. The ends of my guides are pitted, and I am concerned with carbon build up around the stem.
All of my exhaust valves with a "B" are entirely non-magnetic - is that your preference, lm?
250 degrees is only 38 deg above boiling, hot enough for the aluminum to expand, and less than the operating temps of the head. I put a couple of pennies on the point cam under my vise grip jaws to protect it, and the cam came out with little effort. The same for the opposite cam. The cam bearings are a press fit on the cam, and I have always been hesitant driving bearings out, whereby the races and balls take the shock load.
As for the neoprene on the advancer weights, they do not seem to be affected; besides, I am using the Sasche-Elektronic crank-mounted ignition, and removed the weights and point cam from the camshaft, and will cover that end with a cl77 cam end cover. I cut off the tach drive from the l.h. cam, counter bored the end, and made a tool steel washer to fit the counter bore. I shortened the expander bolt, re-threaded it, and made all to fit under a cl77 l.h. cam end cover. BTW, the weight of the stock points system parts I removed was 269 grams [ about 9.5 oz ].

[Dick Eastman]

Dick

You just have to remember that the tool has to go through the guide bore, too. You need to make it a smaller diameter than the O/D of the guide but a reasonable fit on the 7mm dimater to keep it central.

I haven't found many of these guides to be worn but the ones on my '61 project were looser than I like and made it difficult to centralise my Neway cutters.

G

Good point - I've "stuck" a driver or two in my day! I hate lessons learned the hard way!
I presume you have three Neways - been looking at those. Exactly which ones do you have? Also, what does their pilot measure at precisely?