Hello - my 75 350/4 has been rattling for a while, so I opened it to take a look and found that one of the rocker arm retainers had broken off sometime in the past and that a few of the rockers on each side weren't very tight I took off both sets of rocker arms to look for pushrod wear and two more rocker retainers easily broke off - are these super fragile or just aged and brittle? My question is - what parts should I be looking into replacing? Is this just putting new retainers on these rocker arms and reinstalling them? A new set of rockers and retainers? Also new rocker shafts? ... now sure how to check the shaft, it doesn't seem scored, bent or damaged at all will I need any (or all) new pushrods? - these don't seem damaged or bent Any advice you guys can give me is appreciated - I've located new rockers, retainers and pushrods but haven't bought any of them yet - a word or two from an old timer would be helpful here Thanks, Chris side note ... holy cow I love how easy this car is to work on - I wish they still made vehicles like this
Hi there, i would simply replace the retainer buttons and go from there. Warm up the buttons in boiling water before installing them and they will go on better. Yes they just get old and britle. Try not to get deeper into the engine, likely this will solve your issue.
I used that water trick and a long 3/8 extension and a 3lb hammer (metal head) to pound them in. Be careful, you could break them by accident. BUY TWO OF THE BAGS if you go through TA. Most retailers sell them in packs of 16 or individually. If you've never done it before, you will break a couple. Clean up the rockers and shaft with some steel wool and carb/brake cleaner, rinse off with water, and install the buttons.
Are you sure the rattle isn't something else. Did you check your oil pressure? Rockers should have preload. If they are too loose the lifters or cam might be failing. But I have heard people complaining of rattling rockers and find they are getting spark knock. Are you getting noise hot only or just acceleration?
Definitely signs of valvetrain issues going on! Before ordering any new parts here I would pull the Intake and then the lifters one by one to check the Cam lobes on the base circle. If the base circle ware pattern goes across more then 1/2 with width of the lobe, then those Cam lobes and lifters are failing!
Yes. I agree that the cam is probably a problem. Could be the oil being used with low zinc zzdp levels.
thanks for all the replies - I agree taking the intake off is probably the best choice, I'd like to see what the cam looks like - I'm going to start with new retainers and start it up to see how much different it sounds with a bad cam, are there any symptoms other than noise? ... it seems to run smooth through the whole RPM range - the rattling was on acceleration and during highway cruise I haven't checked oil pressure yet, I'll check it first thing after the new retainers are in and it's running
Check your timing if it's at cruise and under acceleration. Sounds more like spark knock. Lifter "tick" would happen at idle hot in or out of gear. . Check your timing advance also. highly doubt it's retainers. That loose to make noise you would probably drop a valve.
it sounds more like a rattle when it's happening - and wiggling the unretained rocker and pushrod made the same sound there may be more wrong with it, but I feel good about this rocker thing being the main sound I've been hearing scored a new set of rocker retainers from an old school guy at the Burnsville MN Napa machine shop - I brought the rocker assemblies in so he could look at the shaft and rocker arms - he said everything looks OK and to just try the retainers - he happened to have a NOS box of them in the back of an old desk drawer, $15 cash bought a whole new set I'm going to carefully install these rocker retainers and put it all back together for a test - the valve cover gaskets won't be here until tomorrow so I won't know until then - I'll post back the results
Are they marked? Or maybe the pushrod "cup" is offset to one side? I don't recall the stamped steel later syle arms having any markings. I know the cast style had an L and an R cast in them, like so:
so far so good - everything's cleaned up and ready to go back in with some white lithium grease - the valve cover gaskets are still on the way so it will be another day or two should these have any play in them after the shaft is bolted down?
Some rockers can have quite a bit of slop even when bolted down. The slop is taken up once the engine is started and oil fills the lifters, and preload is established, then the pushrod rises and pushes upward on the rocker, then the bottom of the rocker fulcrum hugs the rocker shaft which pivots the rocker tip snug against the valve stem. After all that happens, the valve train has zero lash, due to the established preload on the lifter plunger. When you shut the engine off, oil pressure goes away, and depending where the lifter came to rest on the cam lobe, the rockers can be sloppy.
okay thanks for explaining that - that makes sense with what I saw when I first took the covers off - I should have this back together in a day or two with the new retainers and everything cleaned - thanks for the help
haven't given up - painting the valve covers and waiting for a new torque wrench from Amazon any advice or tips for torquing the rocker arms and valve covers back on?
