I had previously posted questions about possible bad distributor and having timing issues on my Chevy 292. Well I found the problem. Exhaust lobes on the cam are shot on four, five and six. Number six is barely moving, I mean barely. I had the head re-done last summer to replace worn valve seats. When I put it together I replaced the lifters, push rods and rocker arms. My compression numbers were great so I figured with a new top end (minus the cam) I would get several years out of it while I figure out if, or which V8 to build for it. Now this is where I shot my self in the foot, I soaked the lifters in oil overnight and put them in. Note I did not lube the bottoms to prevent cam journal damage. Damn, live and learn. So after playing with the timing and setting per Leo Santucci I still had spark knock when going over half throttle. I ended up putting a adjustable vacuum canister, limiting plate, and new springs on the distributor to get it dialed in, still knocked. I played with the timing throwing out Leo's numbers and ended up with base timing at 0 and overall at 28, all in by 3000 rpm. This was a marked improvement but still knocked. So I just pulled the valve cover off to look things over as I have a twitchy vacuum reading on the motor. Viola, found the problem to be little movement on four and five exhaust and barely any on six. So I willing be swapping the cam out, does anyone have recommendations? It's a 292, 4 bbl Edelbrock on a Offy intake with headers. Still running factory rear end and 3 speed. I 'm looking to keep it a well mannered daily driver, a little more performance would be nice but not looking to set any speed records. I tried Langdon's site and the catalog is not working.
Not much on cam help but I would suggest that you pull a couple rod/main caps and check for bearing damage. Most of the time the stuff worn off the cam will wipe out the bearings although I have gotten lucky once or twice.
Yeah, good point! So dumb question, do I need to replace the lifters with the cam as a set or can I do just the cam?
you should replace them all. when you pull the lifters out I bet they are cupped on the bottom as much as the cam is worn off. Be sure you properly lube the cam and lifters as they go in, break it in properly and use ZDDP (zinc) in the oil with every oil change.
I have seen many Chev cams wiped in the 70 's and on . I can tell you that if you are going to keep the car , then do a complete engine rebuild so it's done right . If you need the engine to run to sell the car then sick an common aftermarket cam and lifter in it . Isky , Schneider , Erson , Comp are just a few that makes good cams for the engine . If you give them all the information they can let you know what cam you need . Comp Cams actually has a program to download on your computer that you Fill in the blanks and it will give you some cam recommendations on what cam grind to use . Once you have those specks you can check with any cam grinder to see what it will cost . Retro Jim
Thanks Jim, I know that's the thing to do. Unfortunately it's my daily ride to work to the 283 idea may be what I do, looking at used motors now. The funny part is I've had it for 2years and since day one I had fought to get it too run and never understood what the fuss was about 292's. Everything I have done up to this point was in search waking it up. It has all made progress but it has always had spark knock, popping valves out of the exhaust. After I had the head done I think I have set valve lash 6 times. I would do it and then still have the twitching vacuum and other issues. I was thinking it was me screwing up the whole time, now I'm thinking the cam has been wearing the lobes for quite awhile and finally flattened them enough for me too see. Other than the spark knock I really have it dialed in, man she runs great right around 2 grand. Sounds real nice, which is why I am scratching my head as I watch rocker arms not move. I think I will have another beer or two and contemplate some more. Really looking like it may go V8.
I think you always want the cam and lifters as a set. Either broke in together or both new. Putting new lifters on a broke in cam is probably what did it. A cam and lifters need to be broke in together. If you have to remove them for some reason mark them so they go back in the same spot.
Checked for shavings and wear and looks good. It may help that all the gaskets on the bottom need to be replaced, it's gets new oil added frequently. Money wise at the moment looks like I will swap the cam out and start saving to build a 283 for it. On the timing gear on the cam, I'm thinking I should replace both the gears as a set to be on the safe side. I am thinking that the only way to put the gear on cam is heating the gear up in the oven and pressing it on, is this right? I don't have a press and may need to take it to a machine shop for that part.
Do it right this time. Fresh will then give you longevity and peace of mind. A bump up from stock or two in the cam upgrade will net both milage and power.
You want to check the valve spring seat height and possibility of binding this has been the culprit of many camshaft/lifter deaths.
Correct ! You NEVER install new lifter on a used cam . they won't last . If you buy a used on , the lifters must be marked the way they cam out . If it's a stock cam it's not worth the time and trouble to install a used cam & lifters . Performance cams are the only ones worth installing used . Now you are considering a 283 . Well you will be in the same boat since that engine hasn't been around since the mid 60's . If you are going to install a used engine , just go on C/List and pick up a good 350 for less than $500 . They will last a long time and are dirt cheap as well . If you buy a used engine MAKE sure you hear it run ! If you don't , then consider it as a core to be used to rebuild . When they tell you , "it ran when pulled" , well that means it's junk and needs a rebuild too . I rebuild engines and it's just not worth buying an used engine to install in your car unless you can hear it runs and can do a compression test on it as well . An untrained ear will get you a worn out engine ! Retro Jim
The Jalopy Journal
