On clanking, bent push rods, and rocker arm studs

[foothilltom 33]

Hey guys, so I finally had some time today to look into the loud racket coming from my much-better-running engine (no more carb backfiring). Sadly, I think I've run into some issues and wanted your input on how to go from here.

 

I pulled the valve covers and one of the rocker arms on the 2nd valve of the first cylinder on the driver's side (the 5th cylinder) was completely off the valve. It was just laying off to the side. Further analysis showed the push rod was good and bent. The lifter was still intact and there is no cracking or anything that I can see, but clearly this explains the loud knocking.

 

The rocker arm on the first valve on the same cylinder was also VERY loose, but it still appeared to be engaging the valve. The other rocker arms seemed fine.

 

I also noticed that the "studs" that the rocker arms bolt onto were not of uniform height from the head. In other words, the two studs on the cylinder in question were about 3/8" higher than their comrades. It almost looks like they somehow got pushed *up* from the head. I don't know if this is possible (recall I'm REALLY new at this engine stuff), but it sure looks like they're not in all the way like the others.

 

Can these studs come out on their own like that? How the hell are they supposed to stay in place? The top end is threaded for the nut holding the rocker arm, but the bottom just appears to be a smooth tube that jams into the head. Curious.

 

I also noticed that the lock nuts that hold the two rocker arms (on cylinder 5) are easily turned by hand. The others take quite a bit of effort with a ratchet to move. Does this mean I need to replace the lock nuts (tiny problem considering everything, but i'd like to know).

 

I guess I'm wondering if I can just buy new push rods, tap the studs back down to be equal height with the others, get new lock-nuts, and re-install the rockers and cross my fingers?

 

Can I even tap those studs down or does this suggest some darker problem?

 

This engine was rebuilt some 22 years ago according to the PO, but he didn't elaborate or give details on what was done.

 

The car actually runs pretty good considering the #5 cylinder couldn't have been doing too well (one of the valves wasn't opening for sure), but I'm curious how screwed I am.

 

All inputs and suggestions are always welcome.

 

Tom

[SlimeGold 69 15]

That's why high performance engines have screw in studs. Stock old school Fords and others have press in studs. Big cams, massive valve springs, coil bind, high RPM's or stuck valves will pull them out quick. OR it jumped time and the valves where hitting the top of the pistons and something had to give..the press in studs. May have been why they stopped driving it. Whatever the reason, they will not stay in now IMO. They need pulled out and tapped for screw in studs. I'm sorry that's the problem but 9 times out of 10 the popping you described is a tell-tell sign that a exhaust valve is not opening. I guess I should have kept my mouth shut huh?

 

Your options are to pull the heads to have the screw in studs installed at a machine shop. Or at one time Crane?? I think had screw in studs you could install without removing the heads. Just pull the studs (not easy) tap the hole and screw in the studs. Most studs require machine work to the heads before installing. IMO-I would pull the heads and have them repaired ( screw in studs and guide plates) and checked (valve job included) at a GOOD machine shop. Also check the cam and lifters while it's apart. Or just buy some aftermarket heads.

 

You will need to investigate and find what caused it. The screw in studs will solve the problem if evrything else is well.

 

Also a old trick was to drill thru the boss in the head and the rocker stud and install a pin. But that would be one heck of a job with the heads on and probably not a good idea.

Edited October 11, 2009 by SlimeGold 69

[Print Dad 58]

Hello Tom,

This stinks. I have read what SlimeGold 69 has said and he is right on. His advice on

the heads are 100 true. With that said, I would like to offer a bandaid approach.

1. - First see if the valves are free on that cylinder. This is of utmost importance.

If they are stuck, you'll have the same issues.

2. - I might try fixing the head while it is in the car. I would see if I could get studs. The first would be push in studs, then my second choice would be screw in studs as suggested.

Heck...if you want to gamble, try being sure the valve is free. The try to seat the stud that is there. To do this you must be careful. What we used to do back in the day is put 3 nuts on the stud. Leave the last stud about 1/2 way off the stud. Lock all three nuts. Now with a hammer and block of wood, hit the top nut. You don't want to hurt the threads. Tap till the stud is the same height as the others.

 

if you get a new stud...measure how much the other studs stick up. measure the new stud and measure from the top of the new stud and put a white line. This is the point you want to insert the stud to.

 

Tom, these studs are meant to be pressed in by a machine shop but I have done it before and it worked by hand.

 

The next option is to try and find a screw in stud and see if you can tap the stud hole yourself. This could be tricky and dangerous if not done right.

 

Of course, what Slimey says is 100 accurate and will be a definate fix but if $$ are an issue..you could try to fix yourself. Of course i would change the nuts that hold the rocker. The problem is you can't be 100% certain that the stud will not pull out again, unless you get the valve nice and free.

 

I ma not certain which way I would go, I know having a machine shop do the work will fix things correctly. MY method could be considered a band-aid approach but I have seen it last a long long time if the car is not raced and high revs.

 

I wish this was all better..you have come so far. Push rods are only a few dollars and the stud can't be more than 5 but I just don't know what I would do.

 

I should mention if i had listened to Slime Gold I would have had mt car on the road much sooner.

I only post this with great respect for his advice and wisdom, but I wanted to let you know there are a few less certain options.

 

Something to consider...... Print Dad

[SlimeGold 69 15]

Print Dads idea may very well work. You could give it a try if all the valves are free. If it saves you some money, then it would be worth a try. They may have just pulled out when you first fired it up after a long nap and the valves where stiff or the P.O. missed a few shifts long ago. When stuff like this hapens to me I never have good luck with a easy fix, so I just go all out to make sure it won't hapen again, but that don't mean you wont. Give it a try and see what hapens before you go tearing it down.

Edited October 11, 2009 by SlimeGold 69

[foothilltom 33]

Hey Gents, I'm very grateful for all the excellent advice. I have one quick question:

 

How can I verify that the valves are able to open? I tried to just press on the top of the valve by hand, but the spring seemed 10x stronger than I was able to push. Is there some way to compress that spring and verify?

 

As far as root causes, I can only guess that it was a combo of a valve sticking after 20 years (though I did crank it by hand many times in the early going to ensure everything was working) or perhaps my rapidly and recklessly changing the timing when I was first trying to get the backfiring to stop. Probably not that relevant now to wring my hands, but it is interesting to know how I got to this point.

 

I'll probably try a cheapo approach first, I figure what the heck. If that doesn't work, or I mess something up, I'll probably look at after market aluminum heads from Summit. I wasn't planning on sinking a lot of dough into this, but you know what they say about best laid plans.

 

I guess the good news is I'm learning a lot along the way. Seems like this "press in" studs are really a problem waiting to happen.

 

Anyway, I'd appreciate knowing how I can test the valves to help me decide on the next step.

 

Tom

[69RestoRod 10]

To test the valves their are a few options. Remove the rocker and set a 1"x2" piece of wood about a foot long and whack it with a BFH (If the wood splinters at all make sure you clean anything out of the head). You should feel the valve move, test it on another good valve if you don't feel a difference. Or you can put that cylinder at nearly TDC and fill the cylinder with nylon rope. Then move the piston up till it compressed on the valves and remove the spring with a compressor. Slowly turn the engine a few degrees and test if the valve moves at all. Could be stuck in carbon or could have had a bad valve job and is hanging up on the valve guide.

 

To remove the old studs just put a piece of steel or coper pipe an inch or two long over the stud and tighten down the nut with a washer under it to pull off the stud. Could always try the cheaper press in replacements and some new nuts before buying the thread in. Sounds like the valve stuck and the cam acted like a press and pulled out the weakest link.

[LoneWolf2U 136]

Tom,

I know your not going to like this responce.

But your popping was from a sticky valve and resulted in pulling the rocker stud up.

You WILL be money ahead in pulling the heads off and repairing the valve train.

If you try and do a cheapy fix just to see what if? Then you are not going to like the results when the what if happens.

Breaking off a valve and driving it thru a piston top or doing extreame damage to the block will cost you more in the long run.

A head gasket set is cheap compared to a complete rebuild to the motor.

[SlimeGold 69 15]

Tom,

I know your not going to like this responce.

But your popping was from a sticky valve and resulted in pulling the rocker stud up.

You WILL be money ahead in pulling the heads off and repairing the valve train.

If you try and do a cheapy fix just to see what if? Then you are not going to like the results when the what if happens.

Breaking off a valve and driving it thru a piston top or doing extreame damage to the block will cost you more in the long run.

A head gasket set is cheap compared to a complete rebuild to the motor.

 

This is very true. That's what I mean by not having good luck with a quick fix sometimes. Like I said Print Dads idea could work but if other rockers are loose and more studs are up, I would think twice about a cheap fix. If it drops a valve your in big trouble, trust me, I know. It's up to you Tom but I would think hard about pulling the heads and fixing it right. If it is something simple I would hate to see you spend money, but if more than one stud is up, I'm afraid you will have this problem again...probably when your about 100 miles from home.

Edited October 11, 2009 by SlimeGold 69