Cam woes part II

Desertson · #1 (**permalink**) 10-08-2004, 04:53 PM

I began assembling my new 393w yesterday and its already getting ugly. For starters I found out that for some reason flatlander racing gave me a set of piston rings that are fully a tenth of an inch too big with the kit I bought from them, a little odd since those would NEVER go in a factory small ford block. That was resolved easy enough, but now I have a cam problem. My Comp Cams XE284H cam (see my other thread) slides easily into the block and rotates smoothly and easily for all but the last perhaps 1/16" of its way into the block, ware it seizes in place and refuses to turn. I inspected the bearings thick were installed by my machinist and there doesn’t seem to be anything wrong with them. I tried in the ford factory cam that I took out of the block when I got it and it too seized when pushed far enough back, but it did spin freely and smoothly with the throwout bearing installed and could even go in a little further with no issues. The journals on the comp cam are considerably wider, but when I miced the diameters the new Comp cam was a little less than .001" larger in diameter (Just did a real quick check of the last journal). Honestly I've built a few Chevys before but this is my first Ford, and I know that the for cam set up is quite a bit more complex than Chevy's. The only thing I can think of is to pull the cam plug out of the back of the block and see what that gets me. Am I missing something? thanks... Mike

Rick Parker · #2 (**permalink**) 10-08-2004, 06:25 PM

It is possible that the cam bearings were not installed properly. You may have a burr or nick in one of the bearing surfaces.

I don't want to Hijack your thread but here is something I observed firsthand:

Recently I witnessed the treardown of a real nice 302 that had been built by a very reputable fellow. The engine was in a 66 Mustang that saw a fair amount of open track usage in the SF Region. It had seen several hours of usage. One complaint conveyed to the shop doing the disassembly was irregular oil pressure readings at times and valve lashes that kept changing. This had a lot of high dollar parts including one of the race specific (I think R302?) blocks. What was found is that the cam used by the prior builder was not intended to be used with this particular block. There were significant differences in the journal diameters and the ID's of the bearings. The cam could be "Rattled " around in the bearings from below with the crank removed. It was a huge oversight, fortunately there was not any major damage done.

Rick

Desertson · #3 (**permalink**) 10-08-2004, 10:52 PM

I know I have a run of the mill '71 block, and the bearings must be the right size because the cam fits perfactly other than that last little ways, now if it siezed upas soon as it was in the final bearing i'd know it was simply a mis-match, but rember the cam spins freely when all the journals are allready very nearly in all the way engauged in their respective bearings, Its just that last tinyist bit of travel that causes the siezing, I didnt even notice i had a problom untill I tightened the bolts down on the throwout bearing and all of the sudden, the cam is frozen. I guess my best option now is to pop the cam plug out of the block and get a good look, but i dont want to have to give my bearings any more of a beating by taking the cam in and out and having it sieze. This is really depresing, somethin about me and valve trains i guess just dosn't mix.

Rick Parker · #4 (**permalink**) 10-09-2004, 05:32 AM

I'm not sure what you are refering to? The throwout bearing is on the input shaft of the transmission, it has nothing to do with the camshaft. First of all who installled the cam bearings? Thake the block back to them or make them give you some input on this problem. You will need some specialized measuring and installation tools for this problem to be corrected, which a shop would only have. Visualy check the journals on the cam for any irregulaities. Will the shaft go in far enough so the front journal is below the shoulder at the front of the block? Is the installation of the thrust plate causing the binding?
Rick

Mike Simard · #5 (**permalink**) 10-09-2004, 05:41 AM

I had a similar problem. It turned out to be a nick on the cam journal for the rear bearing. As soon as the cam was the last bit in it got tight. In my case I replaced the bearing becuase it had been scratched by the nick. I would bet that you have the same problem, it could be any journal with the nick on the forward edge. The cam should be nowhere near bottoming out at the rear plug.

Mike Simard · #6 (**permalink**) 10-09-2004, 05:46 AM

Oh, BTW here's what my cam journals measured:
2.0807
2.0659
2.0512
2.0363
2.0211

Jack21 · #7 (**permalink**) 10-09-2004, 03:08 PM

Hey Mike,

It's a Ford, not a Beemer, MB, or swiss watch. Keep it simple, just like Chevys. They both have their idiocyncracies.

Sounds like you have some irregularity on the rear cam bearing that needs to be checked out, perhaps by the machine shop, before you go final on the cam. If need be, replace the bearing. Since you took the old cam out, perhaps replace all the cam bearings while it's apart and in the shop.

If you take it to the shop, have the valley near the lifters clearanced, and holes threaded for a spider so you can install a hydraulic roller cam later without tearing the engine down.

Desertson · #8 (**permalink**) 10-09-2004, 05:11 PM

yea, thrust plate, sorey i tend to mix stuff like that up when I get real unhappy, you wouldnt belive how mad i can get at a cam. Funny its not even a bearing....
Needless to say im not too happy about this and if i have to take it back to the shop, ugh, dont like to think about it. Had a place called Miller Machine down in mass put them in, seemed they had alot of big $$$ stuff getin' put together down there and they looked like they'd in business for about 40 years. I suppose I know thats it's not very complicated, Its just I was hoping there was something I dont know about fords since the alternitave isn't any fun at all.

Desertson · #9 (**permalink**) 10-09-2004, 07:11 PM

Well, upon closer (and calmer) inspection the #2 bering seems to be the problom, theye is a little silver streak in it and when the journal touches the streak it jams. It dosnt seem to be a scratch but more of a high spot. Could it be like a defective bearing? Could it have been crushed and wrinkled a little when they put it in perhaps? Anyway it has to be replaced, suppose I'll take it to the shop. Just out of curiosity, if I could get my hands on the proper tools, is it really as difficult as I have heard to change cam bearings?