Was headed home for my lunch break today, merging onto the highway, gave it some gas... Then sudden loss of power and lots of popping! Fabulous! Look in my mirrors, no smoke. Oil pressure's good, temp is good, so I ride a bit further, watching the gauges like a hawk and looking for a safe place to get over. Everything seemed fine except the loss of power, the obvious miss, and popping through the carb. At this point I was very close to my house, so I took it real slow for another half mile or so, and parked it in the garage. Thoughts going through my head on the way home included, "Yeah, I think I can notch the towers for a 351..." So I went inside and ate lunch real quick, then back outside, started the engine and began pulling spark plug wires until I identified which cylinder had the problem. Passenger side. Good. Valve cover comes off a lot easier on that side. I'm thinking at this point I've got a rocker that came off its pushrod. I looked at my watch, I think I have time to do this... So I pulled the valve cover and there it is. Rocker arm cracked in half, as you see in the pic. I had to clean up and get back to the office, so I did. I haven't checked the pushrod but I imagine it's probably bent. But that brings the inevitable question... What else is broke? Did I wipe a lobe on the cam? Maybe it's just tired old stock rockers on aftermarket springs, and this one was just weak for some reason? The valve doesn't seem to be stuck or anything, although I didn't have time to really look it over. Looks like the rocker broke on the exhaust valve, right? Is that likely to mean damage to my rotating assembly?
it probly broke from age. theres a good chance that there is no other damage. check the push rod on a true flat surface to see if it streight. if you need a cheap quick fix then get another rocker and put it on. i think napa has them in stock. now rember every rocker arm on that motor has moved the same amount of times and seen the same conditions so nows a good time to replace all of them. sounds like a great time to goto roller rockers.
Wow!! Did you find all the pieces? If the cam lobe was gone, it wouldn't be able to push the lifter up enough to cause that (I wouldn't think)
I would also say just old Rocker arm. Those were probably made in what 69? They are pretty tough but I bet all of them have some wear in the cup area as well as all the stress they have taken over the years. I would also worry about the extra pieces but I doubt they would get anywhere to cause any damage. clitn
I was thinking that too actually. These rockers appear to be stock, right? I was thinking just to get it on the road again and verify there's no further damage, I might just go get a parts store/junkyard rocker. Then go roller later. I know I'll need to get pushrods, but are roller rockers compatible with the studs I've got, or will I need new ones? And will that require machining the heads? Yep, found all the pieces. Just two. I can hold them together and you just about can't even see the crack. Very clean split.
When mine went on the race car. I also hurt a lifter. After I fished it out the keeper had broken.= in the lifter. I thought I had all the parts out but a small piece of wire was left and a year later it worked its way into the fuel pump and siezed everything up. Make sure you get it all out.
Y'all think this would be likely to screw up a lifter? Also... Do I correctly remember reading that I have non-adjustable rockers? Or will I need to adjust when I put the new one in?
member to change that oil, and you can get replacement pushrods and rockers for cheap cheap at pretty much any auto parts store. Sorry to hear that though...
One second apart. Clearly we were thinking about lifers at the same time. So, I should be able to tell if the keeper is gone or it it's collapsed by feeling it with the pushrod, I think?
Buy a magnetic drain plug, and get some of those magnets that go on your oil filer, just to be safe. Those are non-adjustable rockers, when you replace them, just torque them down.
So what's the stock ratio of these rockers? 1.6? 1.5? Think some 1.7's will work here without a bunch of difficulty?
I don't remember the stock ratio but it is somewhere in what you said. You do have to have the heads machined for aftermarket rollers, hardened push-rods and guild-plates unless you buy the conversion type rollers and I know less about them. Good luck with it clint
Yeah, I figured. I'm definitely looking for something that can use my existing studs if possible. If I take these heads off for any reason it will be for some GT40's or aftermarket, and that's going to be a while...
Well, the heads were cast on October 12, 19X2. Have to know the casting number on the heads to fill in the X, though obviously it's probably going to be either 72 or 82.
