Old Briggs flathead with worn out exhaust valve guide

F

Flathead Builder

Member
I have a 1969 Briggs 3HP flathead ("Koolbore", aluminum block) with a real nice block and bore EXCEPT for the exhaust valve guide that is worn out of specs with excessive valve wiggle. These engines did not have a separate (replaceable) valve guide. The valve "guide" was just a hole drilled to size in the aluminum block from the factory. Briggs originally sold a set of hand tools that you could ream out the hole and press fit in a new brass bushing. I have the replacement Briggs brass bushing, I just need the tools. Does anyone have any to sell or know a source for them? If I cannot find any, I guess I'll have to find a small engine machine shop to do it. Can anyone recommend a shop from within our forum members? Just to be clear this is not a racing or otherwise high-performance engine, just a stock vintage engine I am restoring.
Thank you for any help,
Michael
 
Last edited:
Follow-up question:
When replacing/installing a new valve guide is it always required (or at least highly recommended) to recut the valve seat? If so, I do not have those tools either and in that case I would leave the job to a professional/machine shop, and not try to do it myself even if I could find the valve guide tools.
Michael
 
Flathead Builder said:
Follow-up question:
When replacing/installing a new valve guide is it always required (or at least highly recommended) to recut the valve seat? If so, I do not have those tools either and in that case I would leave the job to a professional/machine shop, and not try to do it myself even if I could find the valve guide tools.
Michael
Click to expand...
Replied to your email... and for those following along - YES, it is imperative that the seat be cut concentric to the guide after it is installed.


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🏁Thanks and God bless,
Brian Carlson
Carlson Racing Engines
Vector Cutz
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36 years of service to the karting industry ~ 1Cor 9:24
Linden, IN
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bcarlson@CarlsonMotorsports.com
 
If you post your city somebody on here might be able to help and you wont need to pay shipping for such a small job. Since you are not racing, you may have an old mower shop that can do a decent job, maybe. If you do ship it out, have them do both valves. Just checking, but since you mentioned you have a cool bore you do know that you need a cool bore piston (chromed) right?
 
Update (not good news):
I opened up the engine today to thoroughly inspect the internals. Even though the bore looked excellent and measured out well within specs both the side cover bore and the block bore that support the crank ends were REALLY scored as was the mag end journal of the crankshaft. It does not make economic sense to proceed any further with this engine. I do thank everyone who replied and tried to help!
Michael
 
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