Packard Forum Index » Post-War (1946-54)

Any ideas as to what might caused excesive wear- new guide, new lifter, new valve. .004 to .005 clerance and less then 10 houres on a 48 356. Guide wear to the point of zero compression on #1, all others 90 to 100 lbs. It is the exhaust guide. Head of valve will move 3/16 inch side to side-sure beats me!

When the valve was installed, was a plug gauge (J-2553) used to ensure that the valve stem was faced off (tip ground) allowing .030 - .070 inch clearance?

In addition to JD' suggestion, when you installed the guide did you then use a valve seat refacer to regrind the seat using the new guide as a center? That's a must when changing guides to insure the seat and centerline of the guide are concentric with each other. If not, unless they happened to be ooncentric to begin with, the valve can "cant" as it comes down, pushing the stem sideways, and very rapidly wear the guide to an egg-shape and possibly also bend the valve face on the stem.

Yes plug was used to set height for lifter and seat was regrund to center with new guide. Engine ran smooth at first, then rough idel to miss. compresion zero on #1. seat off set seams possible but valve was checked on set after grinding. thanks for the help-Dell

Dear Dell:

Are you sure the guide isn't loose in the block?

It may also have cracked.

Tim; Had to drive out with guide driver and hammer-tight as he**.

No need to be dainty when removing the old guides (and they can be a PITA), but to avoid damaging new guides when installing I usually like to pack them in dry ice for a few minutes. Wear a good glove to avoid frostbite but then you can just push them in with your fingers. After they return to ambient temperature I run a properly sized ream thru them though the guides I've bought most recently from Kanter and Egge were sized perfectly as installed.

On some engines the intake and exhaust guides are driven in to different depths below the block surface so it's always important to measure that before removing the old ones.

Dell,

This Tech Bulletin has some additional reasons for excessive guide wear.

Dave

Attach file:

---

Size: 453.48 KB; Hits: 177

Thanks Dave; I printed the info and when i get to my shop tomorrow I will run the valve in my friends valve grinding machine to see if it is bent-stem is clean and smooth and I have a set of guides on the way from Egge. When I get the guide in I will regrind the set and see what things look like.

I always counter drill the old guide to relieve any stress on the block when takin gthem out. ALWAYS freeze the new guides I have seen cracked blocks from installing tight guides. ON Clipper models on the number 8 cylinder I have drilled and taped the guide and then used a large bolt to pull the used guide out of the block.