silbermustang88

just bought a 68' mustang, owned a few in the past. Love these cars. About 5-10 minutes driving I notice a ticking noise, promptly pull over and tow the car home.

Open up the valve covers to find a popped off roller rocker. Bent pushrods and some are grinding as pictured.

1969' 351W, 1969 block and heads, has a Lunati 468 lift cam advanced 7 degrees and the valvetrain component mods.

Trying to figured out what the cause of this grinding is. Pretty sure the guide plates on the failed pushrod are crooked and had a part to play in it, but as for the others? I've thinking various things like pushrod length, hyd. lifter adjustment, drilling wider pushrod holes, pushrod guide adjustment, even bad gas making things sticky, etc.

Current pushrods are 8.125" - funny that one pushrod in there was a variable "Black Sheep" - high strength type.

I'm trying to determine which size pushrods to get as I obviously need to replace the pushrods. I ordered a pushrod length checker - can I use this to check one roller without the others being connected? I have a handheld starter switch to achieve TDC.

One strange thing about this is that some of the indication spots top of the springs where the roller rocker rollers rest are inconsistent - some a little high, low, and a few are just right (see pics). They cant all be different can they?

Thanks in advance!

2+2GT

Déja vú all over again. You need hardened pushrods. The valves that have exhibited this wear must be replaced. You'll need to file the edges of the damaged valve tips to avoid damaging the valve guide when you remove them.

OCHOHILL

Trying to figured out what the cause of this grinding is. Pretty sure the guide plates on the failed pushrod are crooked and had a part to play in it, but as for the others? I've thinking various things like pushrod length, hyd. lifter adjustment, drilling wider pushrod holes, pushrod guide adjustment, even bad gas making things sticky, etc.

Current pushrods are 8.125" - funny that one pushrod in there was a variable "Black Sheep" - high strength type.

I'm trying to determine which size pushrods to get as I obviously need to replace the pushrods. I ordered a pushrod length checker - can I use this to check one roller without the others being connected? I have a handheld starter switch to achieve TDC.

One strange thing about this is that some of the indication spots top of the springs where the roller rocker rollers rest are inconsistent - some a little high, low, and a few are just right (see pics). They cant all be different can they?

You are on the right track. I am not expert but I can guess a couple things. You definitely need hardened pushrods. I am pretty sure those aren't. The inconsistency can be from not adjusting the rockers properly. The hydraulic lifter can be compressed (there is a spring inside there) effectively changing the length of each pushrod from rocker to cam. Depending upon the engine mileage and poor rocker alignment, you may have worn valve guides. Was the engine burning oil?

Now for the next part:
Let's assume all is good with the valves, you will need to pull the intake and use a hydro lifter modded to a solid lifter and an adjustable pushrod to get your proper pushrod length.

You can go to sbftech.com for more info. The good tech stuff isn't available until you have reached 10 posts.

Now for the bad part:

Where did all those little metal shavings go? What else did this crack mechanic work on?

If it were mine, the oil pressure was good and it didn't burn oil, I would pull the intake and figure the proper pushrod length and assemble the valve train.
Next I would perform a compression test. If the compression test was good enough I would put it back together and run it. If not, I would tear down to replace rings, bearings, seals and rebuild the heads.

Good luck.

67mustang302

Yes, that's from stock non hardened pushrods being used with stud rockers and guide plates, which need hardened pushrods. Also notice the wear pattern on your valve stem tips, the rocker geometry was all wrong on most of them.

Do what was said above, yank intake, buy adjustable pushrod length checker, buy the correct pushrods. I'd go with some Comp Cams Magnum hardened 1 piece pushrods(that's what I run in mine), affordable and plenty strong.

Also it's probably a good idea to pull the heads off and check all the valves/guides, there's a chance that the ones that rattled loose may have excessively worn the guides. Badly worn guides lead to broken valves and destroyed engines. That f'd up rocker geometry can ruin guides too, but it takes longer than vibrating rockers loose.

Edit: Also whatever genius mechanic did that....consider the possibility of a flat tappet cam/lifters without proper break in lube and procedures, so there's the possibility of a cam failure in the near future, if it hasn't happened already. You'll know when you pull the lifters.

mr_velocity

Look at the wear pattern on the first rocker (all the way to the right) and the one that is off. I wouldn't be reusing those rockers either.

kalli

yes, to all of the above and amen to that:

JMD

I agree that most all of the comments are right on, but frankly, unless there is more than meets the eye, (the pictures), for my own car, I would get new hardened pushrods, dress the top of a couple valves, and make sure the guides actually FIT the new pushrods, put it together and give it a whirl...

But then I have always been lucky that way.

Worst case would be a dropped valve, but (from what I can see) I'm not seeing much that would lead me to think a keeper is going to come out or that the valves are so damaged to cause this.

Short of this "worst case scenario" (which I see little if any real risk of happening) it will be cheap enough to take the chance. Just my 2 cents.

It probably took 10,000+ miles to wear through the pushrods, chances are most other catastrophic build issues would have shown by now.

silbermustang88

Thanks for the responses guys.

Yeah, I get the feeling this guy tried to throw things together in order to sell it. He's a nice guy and bought it from a friend who was in trouble. Whatever the history is on it, I'll just fix it. It's a playtoy anyway! =)

I'm gonna pull the intake, install new hardened pushrods and new roller rockers as suggested using the correct EOIC method. Not sure if I need to pull the heads to check valves as this engine has less than 300 miles on it, I don't think that's enough time to wear out the valves is it? I promptly stopped the car when the pushrod came loose.

How difficult is it to replace the hydraulic lifters? I know they have to be soaked in oil, and I can find a proper guide to installation if its not too complex.

As for the heads I'm reluctant to take them off (never done it before) - how difficult is it, do I have to replace gaskets in that case? And how do I check the valves for wear?

Thanks again!

silbermustang88

I pulled the intake today. How can I tell if the cam was properly broken in and lubed? What about the lifters? The lifters look normal to me, and I can see the cam through the holes if I know what to look for...

kalli

the lifters are really as simple as remove old and drop new in. the more complicated part is how to adjust the rockers (so to say play). too loose: tapping, to tight: cam and lifters dead.

to check on the lifters, they should be 100% flat at the bottom (the part that sits on the cam). If there are deep marks in eat or parts eaten off it's dead

for the cam. what you are really looking for is wear on the lobes.
this is what it usually looks like. It doesn't have to be that bad. if a cam starts to wear you can throw it out

compare the lobewith the pen (ground down) with the one right in front of it