460 heads

[Border Patrol]

Had a 460 rebuilt by TMI Inc. Valves on #5 took a crap. They stood behind it and rebuilt it. Now vavles on #6 are giving problems. What the heck can these guys be doing wrong? First time motor had 5k on it, this time it has less than 2k on it. Need suggestions.

[Johnny]

Elaborate... What do you mean by giving you problems?? and when #5 "took a crap" what exactly did it do?

[Border Patrol]

Wiped out the plug completly and I guess there was no vavle left in it (exhaust or intake). Now #6 has left the plug smashed.

[redmt79]

What pistons are you running and what heads are on it?

Also, are the valve heads separating from the stem?

[mudduck]

Please explain " Valves on #5 took a crap". What exactly happened?

You're gonna have to know what year your heads and motor are, maybe get some id #s. Besides what pistons and heads, what kind of gas are you running?

[Border Patrol]

There was no intake or exhuast valve left in #5. Motor block is 79, crank is 79, heads are pre 73. I whish I could give more detail but that is why I don`t rebuild motors = I pay to have it done. Was a complete 79 engine when dropped off but was told heads were bad = they would find better rebuilable heads. Now it seems that 5-8 side can`t be trusted to stay together. Comp ratio is 9:1 running 87 octane with no additives. When it is running on all 8 this thing screams but I only seem to get a month of enjoyment before something breaks. http://7879blueovalbronco.mybb3.org/images/smilies/icon_cry.gif

[79time]

What do you mean by "no intake or exhuast valve left in #5"?

Sounds like the engine builder messed up!

[mudduck]

First pre-73 heads were designed to run with leaded gas. You may have to check into the build your "shop" did. When I used a set of 71 heads on my 77 460, my machinist suggeted some upgrades to the heads for running unleaded fuel. I think there is some guide and valve isssues in those years if you run unleaded fuel. I'm not 100% sure but I think the valve guides are soft and wear excessively without leaded fuel.

I agree with 79time, I think you got an engine builder that didn't know exactly what they were doing. Might have to see exactly what they built and if there is an issue that THEY need to fix for you.

[Border Patrol]

By no intake or exhaust I mean nothing = no stem, no valve, nothing. They are very aware I was or am using this as a daily driver engine and running no additives for valve lube. I hate to blast the shop but it is Tim Meyer Inc.

[redmt79]

Well if you have 9:1 with pre-73 heads, then you have dished pistons so I do not see a clearance problem unless the cam timing is way off.

One possibility is the valve head is separating from the stem, usually a symptom of running too high of valve spring pressures on cheap two-piece valves.

The leaded vs. unleaded this is also a possibility, but that is common knowledge and they should have put in hardened valve seats if the heads did not already have them.

One other possibility is the use of positive-lock seals on the exhaust valves. This can cause the valve stem to stick in the guide under high heat, but usually does not affect intake valves.

I am leaning toward #1, but this is all speculation without knowing exactly what they found with the first failure. For something this catastrophic to happen, you should be hearing a lot of racket in that motor. I would be surpised is there is any amount of head left on the affected piston.

[redmt79]

One other thing could be the keepers or retainers failing, but that seems very rare to me. If the valve guide to retainer clearance is insufficient, or it is reaching coil bind, it could beat the snot out of the keepers and the grooves on the valve stem.

Did they give you any explanation for what happened?

[Border Patrol]

If I remember right they said it was the keepers but alot was missing or scared. I normally try to be calm about this stuff but as I explained to Tim before I brought him the motor I`ve been burned by rebuilders before and now after shelling out 4k for this, calm is waring thin.

[redmt79]

In my mind it is very rare for keepers to fail on their own unless they are mismatched with the retainers. I suspect there is a clearance issue somewhere.

On my 460, I had to mill the valve guides down slightly to allow enough room to prevent the retainers from contacting the guide seals at full lift. This of course will vary depending on the lift of your cam. There are other ways around it, but this is what I chose to do so I could use the parts that came with my kit. Point is any engine builder should be checking all this during assembly.

Did you remember them saying anything about broken valve springs? That is another possibility that could allow the retainer to back off and let the keepers pop loose.

[Border Patrol]

Took truck to TMI on 29 and handed over bad distrubitor and spark plug. Talked about what happened and did informal compression test on 5 and 6. 5 is 120, 6 is 125. Stated I was waiting on new carb yet and would install as soon as it arrived. Aggreed truck is running but not as well as it should. Agreed change carb and plugs and hope for best http://7879blueovalbronco.mybb3.org/images/smilies/icon_neutral.gif . Installed new carb and found #1 plug smashed like #6. Installed regapped plug and truck now gives 2nd gear rubber without problems(c6). Tim is going to call plug maker and distrubitor maker and look for answers. Can a bad distrubitor give a person this big of problems???? I`ve heard of them make a car backfire under heavy load and also shorting out but this????

[redmt79]

The only thing I know of that smashes plugs is pistons. http://7879blueovalbronco.mybb3.org/images/smilies/unknw.gif

Are you sure you have the correct plugs installed?

[jr78f150]

if it has dropped even one valve i cant imagine that piston even being worth the price of scrap.i also agree that smashed plugs sounds like piston clearance problems.
J.R.

[Blue79]

Lots of boost and /or detonation will also smash a plug.

[jr78f150]

to me a smashed plug means its smashed not just a busted insulator like detonation would cause.maybe this should be cleared up as well

[Border Patrol]

Smashed = no gap, and visibly missing ceramic. I agree it looks like something hit it. Tim is hoping this clears up with said carb and new plugs http://7879blueovalbronco.mybb3.org/images/smilies/icon_rolleyes.gif . We discused having compression yet but like what happened before I had compression then but got frustrated and would just hold it WOT to get to work. I don`t want to pull this engine again but I also don`t care to be stuck on the road somewhere either. This truck is expected to pull any of my broncos to the end of the earth and back(texas).

[jr78f150]

sounds like a clearance problem to me,the piston is about all that can smash a plug like that.was the block decked and/or the heads shaved? what kind of pistons were used? i was going to go out to the garage and take a look at the heads im useing on my 429 and see how far the plugs actually stick out but id have to move way to much shit to get to them. id be a little worried about valve clearance myself but surely Tim wouldnt miss that would he? im geussing he is planning on useing maybe a different plug that is shorter,ask and make sure what he is doing because it will make a deffinet difference at tuneup time which im sure will be past the warrenty.

[MIL1ION]

It would be good to know EXACTLY what they did.

If they replace valve seats or valves or mill the heads they must make adjustments to moving parts ie: Valves

Do you have the original work order ?


What are the head casting numbers ?

[Border Patrol]

I have the original invoice yet but it just lists part numbers and general labor. As far as plugs I just replaced with the same that was in there Autolite 46. Parts store said it was 1 step hotter plug. Right now I guess my fingers are crossed that it will stay running. According to Tim this has been his only bad motor. http://7879blueovalbronco.mybb3.org/images/smilies/icon_e_confused.gif

[MIL1ION]

The reason I ask is because of Pushrod lengths.

I have the list of known sizes.
But usually the push rod will get bent before the valve is rammed into a piston.

Maybe check with a engine re-builder page ?

[Blue79]

I still say detonation caused the plugs to be mashed. You said the dizzy was bad, which would throw the timing off and run like crap. But the plug still fired and may have fired in just the right spot to cause massive Cly pressure. I have seen blower engines do this, and even blow a plug up like that just from boost.
My money is on the dizzy and timing issues.

[Border Patrol]

Talked with Tim today and he has talked with Autolite. They think the smashed plugs were caused by detonation (bad distributor). I hope this was the cause and is now fixed by a cheap reman dis.>{} Still hoping to get a refund for the distributor TMI installed.

[blythe_mechanic]

Well if you have 9:1 with pre-73 heads, then you have dished pistons so I do not see a clearance problem unless the cam timing is way off.

One possibility is the valve head is separating from the stem, usually a symptom of running too high of valve spring pressures on cheap two-piece valves.

The leaded vs. unleaded this is also a possibility, but that is common knowledge and they should have put in hardened valve seats if the heads did not already have them.

One other possibility is the use of positive-lock seals on the exhaust valves. This can cause the valve stem to stick in the guide under high heat, but usually does not affect intake valves.

I am leaning toward #1, but this is all speculation without knowing exactly what they found with the first failure. For something this catastrophic to happen, you should be hearing a lot of racket in that motor. I would be surpised is there is any amount of head left on the affected piston.

with out seeing the parts you will never know, but cheap valves and/or n exhaust seat are my picks fr concern

[VA-RANGER]

I got a set of blue thunder heads that would bring that thing to life. SCJ exhaust ports.

[buffs 78 ford]

From experience like one of you said about the seats are they the hardend seats or not. I was wandering what is your lifter preload set at. I kept burning exhaust valves in mine because there was not enough preload and the valves were staying open. What is Ford specs around .060 min I think.

[Border Patrol]

Any body have some insight as to why I may be having detonation problems. Thursday fill up 1 tank with gas and it starts to run rough, switch tanks still running rough. Saturday pull plugs and now #8 smashed, #3 smashed, everything on right bank looks distorted (from heat?). I am hoping this thing will at least last to pull 8,000lbs 3k miles but right now I want to blow a hole through the block so I can either get my money back or have them start over.

[redmt79]

Man Scott, I don't know at this point. If you are truly running 9:1 compression, you should not be having problems running pump gas, although you might want to step up to 91 for a while and see if it clears up. I am really wondering what pistons they put in.

Do you have any idea what your timing curve is, i.e. total advance at what RPM? Are you running vaccum advance in addition to mechanical?

[Border Patrol]

Not sure what timing is set at. Local shop installed cheap reman distributor after the one with rebuild gave problems. This new distributor has not pinged yet and has given great performance = even when asked to run on 5 cylinders.

[Border Patrol]

Well the darn thing left me stranded outside Fort Worth Texas. Lest just say I`m going to rip him apart any place I can. 1 rebuild bad fine but when the second leaves you stranded pulling a bronco its time you do a quality check with your employees.

[TMI]

Come and join this thread.
http://7879blueovalbronco.com/forums/showthread.php?t=761

[Ranger429]

Thread closed. Please keep all of this in one thread.

http://7879blueovalbronco.com/forums/showthread.php?t=761