Pan oversize valves

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Andygears
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Pan oversize valves

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Post by Andygears »

Got some questions about pan valves. I took my abused and poorly rebuilt heads apart, & found: all 4 valves are 1.875 oversize, 3 are unknown mfg. and rear intake is HD #18071-48-1 (marked on valve head), the 3 measure 1/8 from tip to keeper groove, the HD is about 3/16. The stem protrusion is about 1.550 for all. It has steel hard seats which seem tight. Bronze guides all around, movable front ex guide (1/8 up & down) , rear ex guide worn loose on valve stem but seems tight in head, intake guides seem OK. Valve seal angle looks pretty good on both seats and valves, except the rear exhaust which the loose guide shows poor seating. Kinda a mess huh?
The rest of the heads ain't bad, one broken fin in rear and rockers are tight and OK, haven't found any cracks, tapped holes all seem Ok.
So, I'm thinking I can get by with 4 new valves, 4 guides and cut the seats. Hopefully.
Question 1. Where can I source the 1.875 dia. Valves? Seems they were fashionable years ago but neither Manley or Kibblewhite list 'em and V-twin/Sifton says discontinued.
Question 2. What's up with the tip length? It would seem to make a big difference in cover clearance if the top collar was 1/16 further down the stem. That one HD valve I have clears the cover in all positions and it has been reground to a narrow margin on the head.
Question 3. The bottom spring collar is supposed to bear on the aluminum head on the edge? Or on the guide with a gap at the edge? I have multiple varieties.

OK who's the head guru out there??
Thanks to any and all

Andygears
58flh
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Re: Pan oversize valves

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Post by 58flh »

Andygears----The steel seats are enuff to scare me off & shelve them as decoration//However if you do intend to put them in service//I would buy all new stock size valves & Cut seats to match//All new guides-(Iron ones)--& 4 teflon seals/(get the double banded type)-The seals work best if the guides are just faced off to give a 90-degree sharp corner,not chamfered as they are when new.Once you get that nice Flat sharp edge ,just touch a millsmooth file while there still spinning,just to soften the sharpness a little.Measure all installed hights & Tip the ones that need to get to your smallest number when you check the installed hights.//Really look for cracks that cant be seen!!!-(once heads are cleaned//A oven set at 150 will show any cracks in the heads once you bake them-(Oil will ooze out of any tight unseen areas).If they ran before you broke them down/With Patience & care they can be fixed.If you dont have the Machines needed/Be PREPARED to shell out some green!//Not just anybody can fix Old heads!///You need an exp. guy that does them for a living.It may take months & I know ALOT of money to do//(probably more then a set of new aftermarkets cost (IF DONE PROPERLY).Beware those steel seats.I hope you get going soon & good-luck/////respectfully----Richie
Andygears
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Re: Pan oversize valves

#3

Post by Andygears »

Thanks Ritchie, the steel seats have been in place for years, about 40, and the motor ran pretty well before I took it apart for other issues. I found the 1/8 oversize valves from Eastern but don't know yet the tip length. I felt it was unusual that the keeper grooves were at that different length from what I assume was stock. The motor had no valve seals before and even for a well worn motor didn't smoke to speak of. On a post somewhere by Cotton he spoke of facing off the edges of valve spring collars to gain clearance from the covers as a last resort. I would prefer to keep the steel seats because they are "proven" in these heads, the seating surfaces don't seem bad and they are not deep into the heads.
Thanks for responding and will get some further advice from some AMCA guys that do this stuff often, living in Daytona makes some things easier. I've also been offered a supposedly pristine set from a friend, not cheap but fair price in "as removed" condition.

Thanks again,
Andygears
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