Long story short... Had two engines, best of both to make one. Machine shop did the block, Delta Cam did the cam and lifters. And I have the second original cam. Today I'm installing the cam and it doesn't want to go all the way in. On this engine there is one cam bearing in the front, the remaining three journals are just finished holes in the block (for lack of a better term). They are oiled from the oil gallery, but no actual bearing insert. The bearing surface at the rear is too tight. At first the cam would not go into the last opening. I made one very gentle attempt with the new cam and stopped when it resisted. Got the old cam out and tried that. Same thing. At this point, the front journal isn't even touching the bearing yet so I know the problem is the rear one, but why? The cam was in there when I started this. It came out...
Anyway, fast forward. I gently honed the rear hole a very tiny amount and got the old cam installed with assembly lube. It's tight, and seems too tight to me. I can turn it but it takes some effort. No unpleasant noise, no scratches on the bearing surfaces..
Should there be fair resistance at this point, or should it be fairly free when turning? I don't know how to quantify the resistance. Just seems odd to me that it was in there and ran, and now it's resisting going in...
Edit to add... The Mechanic's Manual tells me the bearing sizes for the cam, but I cannot find anywhere that it tells me anything about clearance, other than end play.
Thanks:
Paul
The motor is a Willys F-head 161 cu inch inline 6.
Let me edit this again. Suppose on a chevy inline (model probably doesn't matter) you install a cam. If you then turn or spin it (no timing gear or sprocket) do you need to use a small lever to turn it? (turns without stress but too much effort to be turned by hand alone), turns with your hand around the snout, or spins, say one revolution, by hand?
Paul
In general for me, 4, 6, or v8 (never done a v12...)
* With the gear or sprocket ON- grab and spin as best you can
* When you let go- it should spin on its own, at least a little bit (say 1/8 rev or 1/4 rev). I'd like to see it go a full rev around or near that, but I'll call it "done" if its 1/4 rev of free spin.
* To me, if you grab the gear and spin it and there is NO free spin after you let go, its too tight.
* Ive heard people SAY that if the cam will go in, its ok, it will loosen up on its own, but I'd be too afraid of spinning a bearing or galling to settle for that, unless the engine was expendable and I had several spares.
Willys F-head??????
Here I was thinking this was the "all Chevy Six" section, but its not. Congrats on keeping a rare old inline running!
DeuceCoupe:
Thanks for the info. This morning I measured everything (about 3 times each)Clearances were in the 2 to 3.5 thousandths but on the front bearing (the one with an actual replaceable bearing) there was a high spot and it was generally a little too tight... about 1.5 thousandths. So we attended to that very carefully and now things are moving smoothly.
And yes.. IF I can duplicate the Brazilian version of this motor I should be able to come up with a neck snapping 130 hp.
Thanks:
Paul
I have the same problem. I had my 292 cleaned, and new cam bearing installed. When I tried installing the cam, it wouldn't go all in. I used a fine scotchbrite pad and polished the bearings, cleaned with brake cleaner, lubed, and reinstalled. I did this three times, but it still remained very firm.
I chose to cut down the cam journal when I had this problem. Took about 0.0005 off the diameter of the last journal with abrasive cloth. I had the cam in my lathe to make it easier but that is not a requirement. One benefit of this choice is you don't get grit inside the engine block. YMMV.
Old racer suggested this -
Put the cam in most of the way, then put machinists / prussian bluing around all the journals on the cam. Then shove it in the rest of the way without turning it.
Now, pull it back out a couple inches, again without turning it.
Where the bluing is wiped off, those are the high spots.
USUALLY a little scraping with a razor blade (the goal is to scrape the bearing, not your fingers, but both is still ok) and the high spots go away, then the cam will turn and even spin.
Idea is to just take off whats needed without adding too much oil clearance all around. Tedious job but rewarding when it works.
My machine shop said the reason is that it's not uncommon on these for cam journals to be tight, so that when the bearings are installed, they tend to compress slightly. He said they polish them all of the time. they use scotchbrite mounted on a long aluminum shaft chucked in a drill.