Material selection IC air cooled valve guide

[JohnEvans]

A friend of mine that works on HD motorcycles and I were having a discussion on valve guide material for a old flat head VL Harley. Original was CI and my thoughts were to use the same because of next to none lubrication in that area. The only lube that gets there would be vapor maybe some mist coming up around the valve lifter. He was thinking some form of bronze ie manganese or silicon which I understand they use on the modern engines. I'm thinking with such minimal lube sooner or later the bronze would gall and stick the valve. But not having any experience with either of those bronzes running pretty much dry I don't know. I've made plenty of CI guides for old British bikes with no issue but they all were OHV with reasonable lube available. Anyone with experience using these bronzes in this application with pretty much zero lube?
TIA John

 

[Newman109]

A friend of mine that works on HD motorcycles and I were having a discussion on valve guide material for a old flat head VL Harley. Original was CI and my thoughts were to use the same because of next to none lubrication in that area. The only lube that gets there would be vapor maybe some mist coming up around the valve lifter. He was thinking some form of bronze ie manganese or silicon which I understand they use on the modern engines. I'm thinking with such minimal lube sooner or later the bronze would gall and stick the valve. But not having any experience with either of those bronzes running pretty much dry I don't know. I've made plenty of CI guides for old British bikes with no issue but they all were OHV with reasonable lube available. Anyone with experience using these bronzes in this application with pretty much zero lube?
TIA John

I've done lots of Harley rebuilds in my salad days. I still have the OEM HD flywheel truing jig from my childhood in my shop., LOL. I even owned a '35 VL at one time. Most of my work was on HD 45's and Knuckleheads, though.

IIRC all of those used some form of cast iron guides. If I were you, I'd certainly stick with cast iron since it's the same material originally used and they seldom gave any trouble and were long-lasting when properly fitted.

One issue often overlooked which I'm sure you know about, is the need to ream the valve guides after they are pressed in. This will return them to the proper nominal size after being subjected to a press fit.

Harley used to supply the proper reamers for this purpose. They would be listed in the front pages of the manuals with all of the other special tools required.

You are correct that some parts of the VL's and earlier HD's didn't get proper oiling, The 1935 models were the last HD's with total loss oiling. I recall riding mine and giving a pump or two on the hand pump on the gas tank now and then. The nice thing about the total loss oiling was that the engine would always get fresh new oil.

When HD came out with their first commercial model of bike with OHV's in the 1936 Model E 61' cu.in., the total loss arrangement quickly became a thing of the past.

Happy Trails!

 

[moonlight machine]

A friend of mine that works on HD motorcycles and I were having a discussion on valve guide material for a old flat head VL Harley. Original was CI and my thoughts were to use the same because of next to none lubrication in that area. The only lube that gets there would be vapor maybe some mist coming up around the valve lifter. He was thinking some form of bronze ie manganese or silicon which I understand they use on the modern engines. I'm thinking with such minimal lube sooner or later the bronze would gall and stick the valve. But not having any experience with either of those bronzes running pretty much dry I don't know. I've made plenty of CI guides for old British bikes with no issue but they all were OHV with reasonable lube available. Anyone with experience using these bronzes in this application with pretty much zero lube?
TIA John

I would stay with cast iron.

 

[Street]

you can soak the cast iron guides in hot oil for a while it will permeate into the cast giving some extra lube in a poor environment when you fit them.
Let them cool before you fit them for obvious reasons.

 

[slowmotion]

A solid bronze guide in cast iron is a risky deal. The chance of the valve sticking in the guide is very good. I'm in my 40th year as an automotive machinist and have seen this literally hundreds of times. The problem seems to be a heat transfer issue. The chamber end of the guide will shrink and lock onto the valve. When you remove the guide, the o.d. is now .002"-.003" smaller on that end. In extreme cases, the valve will seize then the guide will come loose in the head, requiring an o.s. o.d. guide. The trick is too fit the guides very loose when installed. But a loose guide does not spell longevity.
I've done lots of VL, UL, EL, & JD Harleys. I have several Youtube videos showing boring and sleeving of them on my CNC. They all wear the guides, but stick with original cast iron. Having to replace them again in 10 years is better than sticking a valve on the road. However, if you insist on bronze, it's not impossible to put a bronze liner in the original guide. Liners do not have the sticking issue that solid bronze does.

 

[gbent]

Cast iron has a proven track record. If your friend must have bronze, Ampco 45 would be my choice.

 

[GregSY]

You could find some way to provide a drop of oil the the guide once in a while. I suppose that might run counter to all that is H-D, though.

 

[JohnEvans]

You could find some way to provide a drop of oil the the guide once in a while. I suppose that might run counter to all that is H-D, though.

YEP!! HDs were known for marking there spot back in day. Had a couple of HDs but my preference was British and Earls Fork BMWs . Of both of which I've had more than a few. Can you say "Compulsive Collector " !!

 

[Greg White]

Love them earls forks,really like watching the springer on my way older H.D.,
think it was a 1943? 3sp. on the tank. it was some wat spell binding watching those forks werk.

wat bout oilite kinda bronze?
Gw

 

[DDoug]

What are air-o-plane engines using ?

I recall seeing some loose ones in a box for a Continental
and they looked like brass/bronze.

 

[JohnEvans]

What are air-o-plane engines using ?

I recall seeing some loose ones in a box for a Continental
and they looked like brass/bronze.

The problem here Doug is the basically total lack of lubrication,in my experience bronze works OK with a good reliable supply of lube.

 

[DDoug]

The problem here Doug is the basically total lack of lubrication,in my experience bronze works OK with a good reliable supply of lube.

Completely dry ? Jeesh.

I thought the normal air cooled lycoming/continental engine has about the same lubrication & temperatures in service as the OP.

 

[JohnEvans]

Completely dry ? Jeesh.

I thought the normal air cooled lycoming/continental engine has about the same lubrication & temperatures in service as the OP.

Remember Doug the flathead series of HDs were designed when dinosaurs still roamed the earth ! LOL So many things about them were rather primitive.