valve guide specs

jhajjar · May 24, 2010

would anyone know what the optimum difference should be for the valve guide and where it sits?

Danno · May 24, 2010

I think the guide bore is .002" smaller than the o.d. of the guide.

jhajjar · May 24, 2010

thanks

comnoz · May 24, 2010

If this is an RH4 head you will be better off fitting the intake guide between 1 and 1.5 with a bronze guide. Less chance of cracking into the intake ports. Since the bronze is close to aluminum in expansion rate it will not come loose at this spec. Jim

jhajjar · May 24, 2010

it is an RH10, right side exhaust guide was so loose that oil would work its way into the exhaust and start smoking as soon as then engine heated up.

comnoz · May 24, 2010

Time for an oversize. Jim

jhajjar · May 24, 2010

yep, what I am worried about is that I was running it this way for about a year now, and i hope I didn't wear it out beyond repair. If that is the case might have to look at a machine shop for the repair.

Danno · May 24, 2010

comnoz said:
If this is an RH4 head you will be better off fitting the intake guide between 1 and 1.5 with a bronze guide. Less chance of cracking into the intake ports. Since the bronze is close to aluminum in expansion rate it will not come loose at this spec. Jim

Is anyone using anything other than bronze guides? I thought cast iron guides went out with bronze skulls.

comnoz · May 24, 2010

Oh they can nearly always be fixed. I did one just last week that took a .028 os guide. It was a 750 so I just cut an 850 guide down to use. Jim

comnoz · May 24, 2010

Danno said:
comnoz said:

If this is an RH4 head you will be better off fitting the intake guide between 1 and 1.5 with a bronze guide. Less chance of cracking into the intake ports. Since the bronze is close to aluminum in expansion rate it will not come loose at this spec. Jim

Click to expand...

Is anyone using anything other than bronze guides? I thought cast iron guides went out with bronze skulls.

They definately went out with me many years ago. As long as I can use an Ampco 45 guide. The older british bronze guides wern't so good though. Jim

jhajjar · May 24, 2010

I might look into the new bronze guides then. I will see if my local supplier stocks them.

comnoz · May 24, 2010

For real Amco45 I would suggest you get them from Kibblewhite Precision Machine on the west coast or Jim Noll out east. Jim

jhajjar · May 24, 2010

Thanks for all the info Comnoz, much appreciated.

splatt · May 24, 2010

Danno said:
[Is anyone using anything other than bronze guides? I thought cast iron guides went out with bronze skulls.

Probably 80% of motor vehical manufactures uses some thing other than bronze.

mike996 · May 25, 2010

The various bronzes - Manganese-bronze, Silicon-bronze, aluminum-bronze and phosphor-bronze- are generally considered the best valve guide materials but there is mixed opinions as to which is best in the specific application. I can't imagine it matters on our old Commando motors.

I believe that cast iron guides are still used on virtually any production engines using cast iron heads. It was certainly true a couple of years ago but that may have changed though I doubt it. One thing that is worth noting is that all modern engines have valve seals on int and exh valves. I have never seen exh seals available for a Commando motor.

Danno · May 25, 2010

splatt said:
Danno said:

[Is anyone using anything other than bronze guides? I thought cast iron guides went out with bronze skulls.

Click to expand...

Probably 80% of motor vehical manufactures uses some thing other than bronze.

I guess I should have qualified that by adding in "air-cooled engines" or "Nortons" since that's what this forum is about. What do F-1 engines use? How about Cummins diesels? I'm sure there are a lot of guys here rebuilding them that would like to know.

comnoz · May 25, 2010

splatt said:
Danno said:

[Is anyone using anything other than bronze guides? I thought cast iron guides went out with bronze skulls.

Click to expand...

Probably 80% of motor vehical manufactures uses some thing other than bronze.

Since the passing of the cast iron head that had an integral guide to save money that is no longer true. There are a good percentage of engines using a powdered steel guide but many are aluminum silicone bronze. I don't know the percentages. Jim

highway · May 25, 2010

I like using cast guides, not the crap that was fitted stock to early commandos, atlases, Tr6s' etc but the ones made by Rowe which are miles ahead in quality match with B/N valves. Pretty much any guide they make can be bought in cast or bronze.
The bore of guide hole is surely worn somewhat hourglass and should be rebored or reamed true rather than the next oversize just banged in. Have a PRO do it. Rick

comnoz · May 25, 2010

highway said:
I like using cast guides, not the crap that was fitted stock to early commandos, atlases, Tr6s' etc but the ones made by Rowe which are miles ahead in quality match with B/N valves. Pretty much any guide they make can be bought in cast or bronze.

>>I always looked at al-bronze guides like this. Since al-si-bronze guides cost several times as much to make due to both tooling and material costs I find it hard to believe that a car maker would actually spend more money for an inferior product. I still see al-si-bronze guides in Mercedes and BMW engines so there must be some advantage.<<<
>>>I also like a guide that grows more with temperature so it doesn't have to be fit so tight. Cracks in the guide hole are a common problem especially with RH4 heads.<<<

The bore of guide hole is surely worn somewhat hourglass and should be rebored or reamed true rather than the next oversize just banged in. Have a PRO do it. Rick

>> I couldn't agree more. Whether You use a iron or a bronze guide. The correct fit is most important.<<< Jim

jhajjar · May 25, 2010

will definitely have the bore verified and reamed before putting in the new guides. Thanks to all for the great advice.

valve guide specs

Similar threads