Classic/Antique Car Repair/1947 Packard head

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Expert: - 11/1/2009


Question
First, Thanks for your help.  I have a '47 Packard 245 6 cylinder apart for overhaul.  How much can I mill the head before I have valve problems?  The cumbustion chambers measure 96cc so I think the head has not been milled before.  The cam lift is stock.  Thanks again.

Answer
We used to figure that .030" was about the limit back in the day. However if you are concerned that it might have been milled before and the tolerances are getting thin between the valves and the roof of the combustion chamber try the old playdough trick. Line the roof of the combustion chambers in the head with about a 1/4 to 1/2 inch thickness of playdough. Then bolt the head on with an old gasket. Turn the engine over two turns, that will open and close all the valves. Then remove the head and the impressions of the valves will be in the playdough and you cam measure the thickness. It will tell you if you have room to mill more off the head. That is the way we did it in the day.
Brad

Classic/Antique Car Repair

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Brad Sears

Expertise

All automotive including antique and collectible. However if the car has been modified I can only answer in general terms and maybe get you pointed in the right direction.

Experience

Automotive tech instructor. Syndicated auto columnist 1970's though the early 1990's. Syndicated auto radio talk show, Ask Brad About cars, CBS Radio 70's through 90's TV Show "Last Chance Garage" 1980's PBS-TV syndicated. Auto instructor for the following companies: Fram Autolyte Holly Carter AMF Ford Motor University Of Conn Blue Hills Technical School Sugar River Technical Center Grew up in a family garage in Needham Mass and turned wrenches from the age of 14.

Publications
Manchester Union Leader, Nashua Telegraph, Motor Service Magazine, Yankee Magazine, Popular Mechanics (Saturday Mechanic early 80's), Los Angeles Times, New York Times, and lots more.

Education/Credentials
More than I care to remember. Basically Franklin Technical Institute in Boston, Northeastern University, Fitchburg State Teachers College, Tufts University, and a lot of factory schools along the way.

Awards and Honors
Moto Award winner. And much more.

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