Combat head rebuild

motorson · Mar 12, 2014

Well after all is said and done I have returned the high zoot valve springs in favor of a stock Andover set from Fred and Ella.

I was using solid neway valve cutting spindles and expanded out the guides more than I like so I bought a valve guide knurling tool and knurled them back down below size and re-reamed them to fit again. I also got an expandable spindle for the neway cutters so it doesn't wear the guide taking it in and out. When reaming the valve guides back to fit I was trying for a .001 fit on the intakes and a .0015 fit on the exhaust. Unfortunately, they seem to have reamed in a bit of a curve because the valve fits just right after using a reamer that is bigger than I want it to be.

I'm thinking I will order new guides and start over. I have a question about how to fit the new guides. The ones I put in were very snug but not the .0015 interference fit that is recommended. I can buy .010 over guides and a .508 or .5085 reamer but I am afraid of how to keep the hole straight while reaming by hand. If you look at my previous posts in this thread you can see the reamers I have. Now that I have had this experience with them not going perfectly straight I am a bit worried.

Bernhard · Mar 14, 2014

motorson said:
Well after all is said and done I have returned the high zoot valve springs in favor of a stock Andover set from Fred and Ella.

I was using solid neway valve cutting spindles and expanded out the guides more than I like so I bought a valve guide knurling tool and knurled them back down below size and re-reamed them to fit again. I also got an expandable spindle for the neway cutters so it doesn't wear the guide taking it in and out. When reaming the valve guides back to fit I was trying for a .001 fit on the intakes and a .0015 fit on the exhaust. Unfortunately, they seem to have reamed in a bit of a curve because the valve fits just right after using a reamer that is bigger than I want it to be.

I'm thinking I will order new guides and start over. I have a question about how to fit the new guides. The ones I put in were very snug but not the .0015 interference fit that is recommended. I can buy .010 over guides and a .508 or .5085 reamer but I am afraid of how to keep the hole straight while reaming by hand. If you look at my previous posts in this thread you can see the reamers I have. Now that I have had this experience with them not going perfectly straight I am a bit worried.

Re; “Now that I have had this experience with them not going perfectly straight I am a bit worried”

Reamer does not have a small taper to lead it in :?:

pete.v · Mar 14, 2014

motorson said:
Now that I have had this experience with them not going perfectly straight I am a bit worried.

My old Combat head, although usable, was way off and the tappets would wear the valve tips way to soon. This was more than likely from the factory like that. Someone probably let too many chips build up on the jig during the days run.

I sent it to Jim but the rest of the head was just sort of beat. He sent it back and I sent him a RH1 in very good shape to re-guide and do the seats. I have since mill/shaved the face and is awesome. It is a combat head with smaller ports. Not a bad combo.

Anyhow, Jim has the jigs to get it right and if the head is in good shape, it's worth the trip.

motorson · Mar 16, 2014

When I looked up oversize guides on eBay I found out that they come every .002" from .500 to .506. I ordered a set of .502 guides and ordered the .5005 and the .501 reamer. I'll see how I do when it all gets here.

Combat head rebuild

motorson

Bernhard

pete.v

motorson

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