After a couple summers of runnin' the crap out of the 235 in the hauler, the motor died. No major noises, just died. Checked gas....got gas. Checked spark....no spark. Pop dizzy cap....wasn't turning. Brought it home and pulled pan and timing cover. About one fourth of the fiber gear was just dust in the bottom of the timing cover. I broke the rest of the cam gear off and cut the hub off the cam. My plan was originally to install a new steel/aluminum timing set and put it back together. Then I read all I could in the archives about I-6's (235-261's). That's where I read what Squirrel posted years ago this was an interference engine. My question is, do I try putting it back together. See if it has any bent pushrods and check compression or pull the motor/head and fix it right. Another question, if I do fix it where it is at, I expect to heat the aluminum cam gear and drive it on, not a whole lot of room to swing the big hammer. Do I lube the gear with oil to get it on OR lube it with Locktite red and hope I can drive it home before it sets up?
You didn't say if it died while running or it just decided to be a butt one morning and not start ? You got to start somewhere. Pull the rocker assembly off since it's gotta come off anyway's then look at your push rods keeping a mental note of which cly. each one came from. If any are bent your just going to have to keep digging further into the corresponding cly. of a bent push rod . Is it a goner ? To early to tell but it's not a lost case yet. I've done a few and all that was needed was new push rods and of coarse a timing gear. As far as changing the timing gear. I've always pulled the cam out and sent it out because there really isn't anything to support the blow's you'll be placing on the cam.
I would pull the rockers and leak it down and see if valves bent, if not I would replace gears and needed parts and run it.
the interference is not between the valves and pistons..it's between the cam and connecting rods....at least that's what I've seen. Although its possible it bent a valve. You might try fixing the timing gear, and then do a compression test, or just see if it runs ok.
Good info, thanks for the replies. The motor was running, hummin' along and just quit. With the pan off I will do a close inspection of the bottom end.
That's what they do. There is a relief on the cam where each rod comes close to it, when the cam timing is off, it hits and will lock up the engine suddenly.
I changed mine way back the 70's in a 59 El Camino. Lost it on the way to work the day I changed jobs and my boss ended up hauling me and my tool box to my new job. I think we heated the gear on the stove to get it to go on.
if you press off the remains of the gear, be very careful to support the thrust plate...it will snap in two if you apply any stress to it (cast iron).
I hadn't ever heard or encountered that type of interference before and I don't think I'll ever see another 235 ever again to see but I sure would like to look into that. I do know that the crank shaft has to be in the correct position to remove the cam shaft. Other wise you'll never get the cam out because the cams journals will interfere with the throw/big end of the connecting rod's. As far as a bent valve. The beauty of such a long push rod they tend to give in first giving us a bit of good luck.
I bought a 55 Chevrolet Handyman Wagon a few years ago, that the old guy who owned it, had made it into a "pick up". 235 six that was rebuilt, and just quit running, and he parked it. It too had a stripped fiber gear on the cam. I gave the engine to a neighbor for his truck, he replaced the gear, and it ran fine. No problem whatsoever. Luck? Who knows? I say, give it a shot; you won't know until you at least try. Anything more than that, stick a V-8 in the truck and be done with it. I am Butch/56sedandelivery.
All the Chevrolet, GMC 6 gears are the same from that era. If you don't want to you don't need to change the crank gear. If the engine is stock your biggest problem will be getting the gear cover off with out lowering the pan. The to lower bolts have nuts on the inside. If you want u can tap the holes in the front main cap so it is easier to assemble. Everything will need to turn over by hand to line up the mark on the gears anyway. Also the gap between the cam holding clamp and cam gear is only a few thousandths so it is a little tough to replace in the engine. If you lived closer I'd give u a cam gear. .. I also agree with the stock push rods will bend first.. Good luck.
A quick update. I looked on the bottom side today with a good light and everything looks good. I couldn't see any marks on the cam and all the pushrods look straight. I'll try to get some pics. After I pull the rocker shaft and spartk plugs I'll turn the cam and crank for further inspection. Hopefully, this may work with a new timing set and fresh gaskets.
The history of this truck dictates it to stay a six. It had a reputation for being loud and obnoxious and it still is. It is true what I said in the opening post about runin' the crap out of it, I guess I did!
Better check the cam gear install real close There is a free play on the cam gear and retainer that needs to be set.
I would take the cam out now to change the gear. It's really on tight and the new one should not be put on with a BFH. Press is the way. I don't think you can support the end of the cam to get the new gear fully seated with the cam in the engine. Put #1 on TDC and it will clear the crank to pull it out. Or is it BDC? I forget, but its one of those.
the old chilton book says get your reliable helper under there with a pry bar to hold the cam forward. Not what I would do.
Same happened to me. Only a bent pushrod. You don't seem too worried. Get it going. Replace the gear and go for it. Sent from my iPad using Tapatalk
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