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pninaud
06-14-2005, 12:20 AM
Hello fellow enthusiasts.
Have any of you managed to replace all the camshaft bushings in the crankcase and timing cover? I understand this can be a tricky job that involves line-honing the bushings and boring them as well.

I am considering replacing the bushings myself and lapping in the shafts to get a good fit. I may have to face the bushings for the right end-play.

Any tips on performing this job (like removing the bushings from the timing cover) would be great!

Also, should I consider replacing the tappet guides?

T. Cotten
06-14-2005, 07:38 PM
If your cam journals are worn, most modern bushings will be a slip fit even when pressed in, however they usually have minor binds. Line reaming or line honing tends to remove a lot of stock.

So ideally, undersized bushings should be indexed and bored on a mill: Obviously a significant expense.

But most practical is to ink and scrape the standard bushings. A common triangular scraper will quickly remove high spots indicated by felt-tip pen ink with trial fits.
Scraping in a criss-cross pattern, and then finishing with an impregnated nylon brush gives an oil-friendly crosshatch, and leaves a broader and truer bearing surface than a blind resizing would.
It is then truly hand-fitted

(PS: Most lapping compounds embed into bronze bushings.)

pninaud
06-14-2005, 08:21 PM
Thank you Terry,
I appreciate the advice. I really want to do this myself, and now I think I can.... I am glad that I will not have to go through the expense and risk of having a high-dollar shop involved.

Should I heat the timing cover and crank case before pressing out the bushings and upon inserting the new ones?

Cheers, Patrice

T. Cotten
06-14-2005, 08:37 PM
Tom here,

Yes, the manual suggests a proper temperature.

Now that oversized pushrods are available from Eastern, it is probably more economical to hone any badly worn guides you have, leaving them in place.

AdminGuy
06-15-2005, 02:43 AM
terry, tom, whatever... hee-hee.

I really recommend taking a night school course in basic machining techniques for the uninitated. Using a lathe, mill, talking to your instructor about your current project , etc.

Also talk to the local hotrod auto boys (the greasers). You may find someone retired that likes and works on flatheads from home. Many things are universal.

Great shot Patrice - it was nice to meet you both briefly at Tenino a couple years back. Comin out again?

Myself, daughter and Chevy pictured upcountry doing that cowboy thing horseback for a couple days mid April, out of season -real cheap, good friends. Less flys, dust, bears and sometimes you wake up to snow. We ride no matter the conditions. Little girls love horses! May get a phone call mid summer for round-up. Two thaws this winter and its real dry. May have to help two old fellas move 750 head onto trucks to water. Narrow shoot, can only move 35 at a time down one section. Good place to get killed. I've got standard in first aid and/or can stich guys up if need be.
Horses are like bikes - but they think. Sometimes alot smarter than you'd give credit. Gotta trust your horse!

So there you go. I'm a bit of a cowboy. Reality based - no fantasy.

pninaud
06-15-2005, 07:28 PM
Thanks Tom and Admin,
I took a couple of years of machine shop training, and yes it really helped when I had to fabricate spacers, bushings, and the like for my 1924 Chief.

Tom, who is the supplier of those oversized Chief pushrods? If I can get them in +.002 then it will help take some of the play out.

Since moving to Austin, TX I try to visit my family in Seattle once a year.

Cheers. Patrice

T. Cotten
06-15-2005, 09:48 PM
Eastern MC Parts of South Carolina, if my mem'ry isn't befuddled.

They might only come in .005 and/or .010" oversize; either way, a Sunnen hone or similar machine tool would certainly be required.

The guides are quite hard, and require some effort and patience to get honed right.

swall
06-16-2005, 01:27 PM
I got my bushings out by using a "reverse heat shrink" technique. The biggest problem is that the coefficients of thermal expansion for bronze and alumium are very close, so you have to heat the aluminum and chill the I.D. of the bronze bushing. Then it should tap out easily with a shouldered driver.To chill the bushing I used a popsicle, "turned down" to the correct size. On the cam cover, the big bushing is mostly steel, so that one you can get out with heat alone. But chilling the I.D. helps the process along.