454 that eats push rods

[kbelcher]

I own a 1971 454/365 that seems to love eating push rods. I got the car back in August and it had a bent push rod at the time. I made the prior owner fix it before I would purchase the car. He replaced all the push rods, I believe.

Last night I was driving the car and I got another bent push rod. As with the first bent push rod, I was not driving the car hard or were there any unusual conditions that would cause this to happen. Current set of push rods has about 200 miles on them.

As far as I can tell from the receipts of prior work, the engine is completely stock. This includes matching numbers on the heads. Since all prior owners save their receipts, I see nothing for performance cams, lifters, etc.

Any ideas? Sticking lifters? Sticking values?

 

[cruzer99]

My hunch is that he replaced the bent one only. There could have been several that were on there way out but only the one was bad enough to show up when you bought it.
Check the valve springs because some rebuilders like to put heavy duty springs in thinking it will make the car run better. All it does is bend push rods and flatten cams. I would suggest replacing all of the push rods yourself (that way you know), and see how everything goes.
Good luck

 

[wallyknoch]

Call me at [ 1-313-292-9200 ] and I`ll try to straighten you out.

 

[mrvette]

somehow I suspect someone has too tight a clearance on the valve spring clearances when the valves are open as far as that cam wants them to be...and they are binding...if not outright, with certain rpm's...the coils bounce around, and if they collide with one another...it's over for the pushrod/cam...lifters...

might even break a stud...not unheard of...

if someone put a 'rev kit' in there...you might be with too thick a coil for the vertical space, and inducint bind where there may not be normally....

all sorts of variations on any one or more of the above themes...

GENE

 

[sscam69]

are they hardened?

Gene pointed another good area to explore.

 

[clar2001]

Sticky lifter was the car stored for any period of time ?

 

[kbelcher]

Lifters are hydraulic, not solid lifters if that is what is meant by harden?

Also, the vehicle has been in long term storage. Engine has 1500 miles on a rebuild dated back to 1986...

I pulled the left bank of plugs out last night. All 4 looked OK. So it sounds like the right side. I next pulled the left cover off and looked at the rockers and did a visual on the pushrods. Again, everything looks OK.

Next I move to the right side. I believe this is where the original issue was when I bought it. Maybe it is the same one again?

Stay tuned...

 

[Brack]

The 82 I just bought was put up for a while.....everything was going fine ...UNTIL....as Clar2001 said....A lifter froze up on me and lots of stuff broke / bent...push rod / valve ......kinda stunk ...motor was original with only 80K on it.....anyway....im in the process now of going thru it ( heads are in the shop now ) and everything checked out fine...gonna go back standard with everything...... and its given me a reason to detail the engine compartment...

good luck

 

[sscam69]

Lifters are hydraulic, not solid lifters if that is what is meant by harden?

Also, the vehicle has been in long term storage. Engine has 1500 miles on a rebuild dated back to 1986...

I pulled the left bank of plugs out last night. All 4 looked OK. So it sounds like the right side. I next pulled the left cover off and looked at the rockers and did a visual on the pushrods. Again, everything looks OK.

Next I move to the right side. I believe this is where the original issue was when I bought it. Maybe it is the same one again?

Stay tuned...

hardened chromoly pushrods, more resistant to bending/breaking.

 

[kbelcher]

Re: Re: 454 that eats push rods

hardened chromoly pushrods, more resistant to bending/breaking.

OK, now I understand. I'm not sure but I would guess standard pushrods. Might be a good idea to use hardened on my fix.

Left side of the engine checks out fine. So, on to the right this weekend.

Thanks to all for your input.

Kevin

 

[grumpyvette]

the pushrods do not just bend by themselves, it takes over 1000 lbs. of force, there are always clearance issues like spring bind, pushrod alignment, Rocker ratio, retainer to valve guide, problems that causes the pushrods to bend. You must find the problem and correct it, the most common problem, is installing a cam that has greater than stock lift or duration, without checking the valve train geometry and clearances. If you have swapped to a different then stock cam, that is more than likely your problem. If you don't know exactly how much clearance you have between the edge of the valve and the piston, between the slot in the rocker arm and the Rocker stud, the valve spring retainer and the valve guide, and how much clearance you have at full lift on the valve spring before you get into coil bind. (I'm betting you do not, simply because most hot rodders never bothered to check, until they start having problems like that problem you're having to the pushrods ) I think it would be money and time well spent to find out those clearances, and I'm reasonably sure thats a process during which you'll find out why thoses pushrods bent

 

[bigvette1]

Most areas have been covered. I would do 3 things.

1. Find out what cam in the car and what lift. Get a dial indiactor if needed or some help and find out.

2. See if the rockers are the long slot type for a higher than stock lift. Stock on a 454 are usually good for only .490" safely. Less than this with lift >.500 will interfere with the motion.

3. Get a pushrod length checker and see what rod length you need. Your's may be too long for the lift of the cam and the spring height.

Sounds like a lot - maybe or if you can or know a performance shop, ask them to do this for you. In the end it will pay off. Right now you are tearing up pushrods and the whole valve train is at risk or hoepfully not damaged. Good luck and take your time.

JP

 

[kbelcher]

Hello all

Well over the weekend I found that #8 exhaust rocker arm was cracked in half. No bent pushrods that I can find.

Plan for now is to replace the rocker arm and see what happens. If #8 goes bad again, I'm thinking it is time to pull the head...

Still open to other suggestions.

 

[CHEV66JB]

Re:

Dunno if this applies or not with this scenario, but in the Spring I bent a pushrod in my 327 of my Chevelle, and it happened because that valve had worked had actually worked its way LOOSE, and the slapping of the pushrod from the lifter to the rocker arm actually bent and finally broke the pushrod. Is it possible that the pushrods in yours might not be torqued down ENOUGH? Best of luck with finding the problem-

Jim (CHEV66JB)

 

[kbelcher]

Hi all

Good news, I've discovered what was causing the broken rockers and bent pushrods.

This is a good one...

We (friend and I) replaced the rocker last night. All went well. Still caused me grief not knowing what the real issue was behind this. As we ran the engine we discovered that the right exhaust was not omitting any exhaust and pressure was building up. Since my exhaust is getting old, we decided to remove it to see what was obstructing the flow. We original thought it might be the heat riser. However, we found that had been removed by the prior owner. Cut the exhaust pipe out and found that the inner wall of a double wall pipe had collapsed and was not letting exhaust flow out! As pressure built, and there was no place for it to go, the exhaust values had a harder and harder time opening. So, once the pressure was too much, the rods would bend or the rocker broke.

Talk about relieved! This was a fun one to discover.

Got to go and order a new exhaust for the 71 to install this weekend!

Thanks to all for your help!

Kevin