July 10, 2012 at 11:49 pm #7417
I’ve actually seen cam bearings done (cam bearings machined), but not the cam itself. It’s not as uncommon as it might sound, and from my machining coursework, depending on what amount of material they’ve removed, it can be “just fine.” Most of the time (and when I was building my engine, there were at least 8 others being built around me in the classes), it seemed pretty common to me that when the cam bearings were torqued down sometimes the cam wouldn’t spin freely. Sometimes it just meant that a very light sanding (I think with an emery cloth)and others it meant very precise measuring (with a bore dial gauge, if I remember it right) and then a very slight boring of the cam bearings to get everything perfect. Bearings oftentimes aren’t perfectly matched, one can differ slightly in bore size from another – there’s usually a tolerance to it within very tight specifications. I think what we did on mine was some very exact premeasuring to ensure consistency among the bearings, and if I remember right (been about 3 years now) I had to purchase another set of bearings to get the pre-installed set to match the tolerances we wanted. We did not machine the cam, however. I’ll have to ask about that.
I understand the desire to “get it together,” but your instinct is dead on to get it right no matter how long it takes. A slight delay now might mean years more of it running right. As somebody who’s had a post-build glitch or two that made me consider what I’d have done differently if I’d have rethought it during the rebuild (and mine runs pretty damn great now), take your time and think every little thing through, and seek advice.July 11, 2012 at 7:48 am #7419
thanks for the info. for the pistons, i just got what D&D recommended, he said i would not have a problem with over heating if the fluid injection was working right. also, the compression will be a little less than original (not much) because the head gaskets are thicker.
i talked to several machine shops today on the phone and none of them want to line bore the cam bearing holes of the block. most of them told me they did not have the tooling to go that small other than with a hone. i think i am just going to mail the block to D&D and be done with it. looks like shipping will be $80 each way. i will end up having around $600 in a new cam and bearings being installed with shipping. that stinks! i should have sent it there to begin with.July 11, 2012 at 9:23 pm #7420
I ordered basically all of my stuff through D&D as well, and they are a great resource for advice and parts. Yes, the original engines used cast pistons and they’ll be fine with a working fluid injection. The Jet Hot coating was just an added precaution. And yes, absolutely, using the thicker head gasket will significantly lower the compression. I did the same thing (Jim Noel can give a dissertation on that subject!)
I guess my big question given your situation would be whether it was the bearings themselves or the actual cam bore that was the issue on your original installation. Like I said, sometimes the bearings can be mismatched or inconsistent in size and that can be the problem. The only way to know that is to measure the cam bearings with a micrometer prior to installation to ensure that every one is the same size or within the spec. I would guess a machine shop would do this, so then it’s down to the cam bore. If it is the bore that’s the issue, machining the cam bore is the solution. As it sounds like you’re not doing this work yourself, you have to trust the professional that’s telling you what the problem is. I definitely put some extra funds in along the way, as it pretty much is with any engine build. It always costs more than you thought it would!July 13, 2012 at 7:50 am #7422
i am stepping away from the entire thing this weekend and going to work on another Oldsmobile. i will take another look at my situation next week and go from there. the good thing is, my transmission was $1000 less than i thought it would be so i am still a little ahead of the game. i have talked to several machine shops about this now and most all of them are telling me that what i have should work just fine. the trouble i am having is the “should” part. with this being the original Jetfire block i don’t want to have it ruined by taking a shortcut.July 20, 2012 at 9:45 pm #7425
My machining experts (instructors where I built my engine) thought it was unusual to machine the cam. They would not have attacked it that way, they said. It seemed to them to be an afterthought when the cam bore, cam, and bearing sizes should have been checked prior to installation. If there’s any issue after installation, their first response would be to remove the cam, lightly scotch bright the bearings, and then reinstall. (which would likely be the only time to reinstall, as you cant do that over and over) If there was still an issue, they’d then remove and check the bore, which would be the first thing to machine if it wasn’t right. Although they also said it was unusual for a bore to be off, they rarely have to do that -the issue is usually with the bearings being slightly off.July 24, 2012 at 5:41 am #7434
i have called around to several machine shops and only got one that would look at it to give me a second opinion. they checked it all over and said they could do it right if i wanted them to but they also said it would be a wast of money because what i have will work just fine. i think the cam has been in and out of this engine about 20 times now. i am going to start putting it back together and trust what they are telling me. i am taking vacation next week and hope to have this car most of the way back together by the end of next week. i am still needing piston rings but i should have them this week.July 29, 2012 at 9:21 am #7437
AT LAST!:woohoo: i am back on this project. after some big delays i am now putting it back together. i only had 4 hours for it today but this is what i got done so far. i calculated the compression and it came out to 10.0 on the nose. i am on vacation this week so i plan to have it mostly done. more pictures to come this week!
You must be logged in to access attached files.July 30, 2012 at 2:54 am #7439
that’s pretty! Looks terrific. Good luck. Keep posting those pictures, they’re very cool.July 30, 2012 at 7:21 am #7442
i was not sure if i liked the color of the exhaust manifolds but now that they are on the engine i think they will be ok. i am not sure what color they were when these cars were new. i painted these with POR exhaust manifold cast iron paint. i have not decided yet but i may change the bearing shell on #8 rod cap. there was a small pit in the surface of it. i don’t see that it would ever hurt anything but if D&D can sell just one rod bearing i will likely change it. i also need to order a Pertronix.
You must be logged in to access attached files.July 31, 2012 at 8:01 am #7445
I haven’t had a whole lot of luck keeping paint on the manifolds or the pipe from the manifold up to the turbo. Your color looks like mine did. They just get so hot, it seems like the paint always gets cooked. I’ve tried a few different paints, the POR stays on the best for me, but I’ve still had to recoat every year or so, which is a pain when the engine is in the car.
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