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One Odd Failure

new 3/17/03, updated 3/31/03

I got a call from TKY today, he is at Ft. Bragg and I told him we miss him, support him and pray for him and his every day.

He told me Ray’s had a peculiar cam failure. It was a come back. Ray’s checked their work and the sprocket welds were fine yet the engine had bent valves all over. Ray put the engine at TDC and the main chain was in time at each external cam sprocket.

Ray & I conclude that something slipped at the crank end. Worn sprocket? Worn chain? Something broke?

It is important not to over react but the car has only 84k on it and looks like new condition, it is only one failure, so far (of this type).  I assumed if we welded the cam sprockets we have a 250k motor.  The computer prevents over revving.  Ray will contact me, (or I’ll contact him) once he gets the engine out and gets a good look.

Worst case you know some chains wear out.  In the old OHV days you took a timing chain, turned it on its side and held it horizontally under a shelf and measured the droop. Too much droop (+1/2”) and you replaced the cam. Not to cause a panic but I wonder if the primary chain is wearing? Get a new one, say it is 40” long, measure a used one, say it is 41” long? 

Le petite pricks at Fud never warned us about the power steering fluid either, we had to figure that out on our own.  We may have enough welded SHOs that are pioneers, (and proof that Fud never fully developed this into a finished durable product ). Ok I’m fighting off dashed dreams and a minor case of panic again, this IS only case #1 of this type of failure but it was totally unexpected. I guess I am kyniptted because I assumed as a matter of dogma that if I welded my cams I would never need a new $13,000 motor.

I am going to get out veterinary tools catalogue and make a house call to those worthless steers in Dearborn.

Details to follow.

(Just talked to Ray again, he has valves bent all over the front head, he assumes he has bent valve on the back head but has not checked them. He will turn the engine over to TDC to verify the timing marks on both top external cam sprockets. He has a IH dealership next to him and will do a cold oil analysis, better than none.) 

Sunday, 3/30/03 I got a phone call from Ray’s in Detroit. Ray was upset because he had a chance to tear into the “Odd Failure” and figure out what happened. To understand what happen first we may find it helpful to have a small lesson in SHO anatomy. 

All SHOs have 4 valves, 2 intake valves and 2 exhaust valves. One vital difference is how and where they manage the introduction of fuel. Both engines have a butterfly / intake system that has one runner for low RPM and another for high RPM. In the case of the V6 both runners match to the head into a common runner where the fuel injector sits just above the two intake valves which always both see fuel and always open.

The V8 arrangement is very different. The butterfly that opens the secondary intake path is just above the head, in the lower intake manifold as opposed to the far end of the intake path. The fuel injector sits just under the butterfly location in the lower intake manifold in the low RPM intake runner. The two intake ports stay independent so the low RPM valve is always “wet” – that is it sees fuel, while the high RPM valve is always “dry”; it never sees any fuel.

The dry secondary high RPM port with its own valve still opens every cycle but because it has a closed butterfly just above it, it is a dead back-water during low RPM operation.

Some of you may remember the phrase “Italian Tune-up” from the 1960’s. One might take a city use car and get it out on the highway and run it close to red line for a while. Theory and experience was to decarbon the intake valves with fuel, (which acts as a mild solvent). 

Based on Ray’s teardown the dry intake valve carbons up. It never sees fuel, never gets cleaned. Ray thinks that in time (V8 SHO had 84k) the valve stem can build sufficient deposits to slow or impair its action. In this case the buildup of carbon was enough so the valves fail to retract even with spring pressure. So with 4 welded sprockets and nothing slipped the car had 3 intake valves bent or headless; all secondary and all on the front head. 

It may be ironic that Ford accuses sprocket failure to abuse and neglect. I wonder if this can be attributed to easy driving or cheap gas? Well by DESIGN the stuck valve is dry and NEVER sees any fuel to clean it. Nothing the owner can do to either clean or foul the valve. Ray says the oil looked fresh and the engine generally was very clean through out. The car was anything but abused or neglected.

Since the carbon buildup may be motor oil weeping through the valve guide does any one brand of oil do any better than another? I don’t know? Kirk inspected my valves this weekend and Mobil 1 doesn’t evidently prevent valve carbon.

I introduced Ray to Doug Lewis so they can compare their experiences and get their collective heads involved. I look forward to the fruits of their collaboration. Ray is now eager to go to this year’s convention in Madison which will be all the richer for the addition of his experience and presence.

It took a while to sort out all the cam sprocket issues; it only stands to reason it may take a while to sort out this issue. I have some fear that at one time (last week) I assumed if your cams are welded or pinned we have a 250k mile engine. Ray, Kirk and Doug all notice a pattern of carbon build up on the dry intake valves. If the cars need head rebuilds before their first tune-up that would be another interesting legal issue.

Ray tells me the car has 3 secondary valves bent on the front head only. Rear head is fine, except for carbon buildup. Doug tells me he recommends owners perform an Italian tune-up, at least twice a day to avoid carbon build up. Doug is skeptical that carbon buildup would prevent an intake valve from retracting.


So what's the thinking here - That this buildup of carbon could actually be the cause of the cam gear failures? Something to consider at least? Interesting...

Dave Garber

that is what was going on with my 97 the #1 cylinder was giving me a misfire the problem was the valve not closing all the way all the time ,sometimes it was ok I had to spend a day with the shopvac and some berrymans closing and cleaning all the secondary valves

Nick Berge

A note of caution, you can clean enough carbon to plug your oil filter and starve your bearings. Without removing the head all the carbon is dumped on the piston top. If you are lucky it might go out the exhaust or might not.

The solvent also washes the oil off of the cylinder walls and one could risk seizing a piston. I hope all goes well for you Nick, but based on advise and experience for both Kirk & Doug Lewis I can't recommend folks flush all the carbon using any solvent all at once with the heads on their car.

Not that I know what I am doing, I value your input and we are all trying to best figure this new problem out.


Moral of the story: Ford gave the car a gas pedal, use it.

Ryan Dudek
98 Black

The carbon came from the PCV gasses that condense in the surge tank and then is ingested by the secondaries when at the high rpms. As you stated the reason the primary intake valves are clean is because the injector is washing that valve down at all times.

I have been thinking of a solution since last summer and have come up with a couple. I will soon try to completely bypass the PCV into the atmosphere using an extra SAI pump I have. Of course this has it's environmental disadvantages.

The second and preferable one is an alcohol injection system that fires into the surge tank only when the secondaries are open. This would keep the surge tank and secondary valves clean and be legal. Also would allow you to fully utilize the low octane fuel as well as cool the intake down. I was considering a 100% ethanol mixture to be injected.

Paul Nimz
'97 TR SHO
'93 EG mtx SHO

Sure it could. If the valves are getting that kind of buildup, it is entirely possible that they don't open as freely as they should either which would put more stress on the cam gear(s).

That's not to say that the design isn't still flawed or that welding isn't necessary. But, the relationship between these parts is to intimate to ignore any possibility at this point. I've worked on engines all my life and I remember the 'old' 70's and 80's heads with the Quaker State oil sludge, carbon, etc and the effect it had on the valves, lifters, rockers and cam. They rarely if ever seized but, for sure they didn't operate as smoothly as they did after being cleaned up. Couple this with the inherently weak design of the gear's attachment to the camshaft and there could be a relationship there in the case of the V8 SHO engine...

Nothing to go to the list with but, nonetheless something to 'ponder'... 


It's not that it couldn't happen, but to happen to 3 valves at the same time is very unlikely, as one valve failing wouldn't affect another valve. They would have to have identical buildup on them, and even then, 3 valves failing at the same time from carbon buildup? I'm not sure who Ray is and I'm sure he is a lot more experience then me, especially with this motor, but I find this extremely difficult to believe.

Curiously, is there any way you V8 guys can activate the secondary butterfly motor, so that you can do a decarbon procedure with the intake on? Or is it something that has to come off to clean those "dry" valves.

Mike Kopstain
Midwest SHO Specialists
827 North Chestnut Avenue
Arlington Heights, IL 60004

Could have been something that dislodged a large amount of carbon in the runner area. This may be why three went nearly at once. The build up on them is nearly identical from what I have seen.

If you had one front wheel off the ground and the car in gear you could rev the motor up to the point the secondaries were open or a bit safer way would be to manually open them during a decarboning.

Paul Nimz
'97 TR SHO
'93 EG mtx SHO

I just have a hard time seeing how that could happen, but I suppose it could. 

Mike Kopstain

One front wheel off the ground? I think you would rather have both front wheels. 

How would you manually open the secondaries?

Rene Carlos Cruz
Warren, MI
98 SF

You don't need to activate the motor, you can follow the cable out of the motor the the peg that it mounts on and pull the secondaries open by hand. Also, IIRC, Mike Ivy did a test a while back and found that the IMRC motor is activated before the car hits the rev limiter in park/neutral eliminating the need to jack the car up. Of course, it would be fun to put the car up in the air and clean the carbon out while balancing your tires ala Crazy George at the convention.

Ryan Dudek
98 Black
Enjoying a day off work

Those who remember the old breather oil caps in open crankcase systems know the amount of garbage that is produced. washed my screens out with naphtha semi-regularly.

Paul, your idea has merit (using 50's / 60's technology :) but you'd have to write a procedure on using the injection kit to prevent the problem of literally floating the valves should the Italian tune-up secondary duration instructions not be heeded...heheh. I would think that a 50/50 alcohol / water solution would also do the job depending on the atomization of the spray. At least no immediate damage would occur should the bottle run dry like in the old days to prevent harmful detonation.
I can't remember but did your inline fuel filter idea work?

Bill H.

No the fuel filter didn't work, hard to filter a gaseous substance with a filter made for a liquid medium. I would not be adding very much alcohol and want to stay away from a water mix due to power loss issues.

Paul Nimz
'97 TR SHO
'93 EG mtx SHO

That is why I used a shopvac with custom end and closed the valve I was working on so the motor did not overload on startup, there was also a very good visual inspection of each valve before it was reopened . after all was done and bolted back together I did a test fire with a perfect start ,then I shut it down dumped in berrymans motor flush ran it for 5min and changed the oil witch did not look any different than normal

thanks Nick


Hi, Rick Reeder again. gonna get my cams welded tonight so the locktite wont be an issue any longer, however it held up fine as a temp repair. anyway, my question is this, I have cleaned the lower intake of all carbon but am wondering how to clean the chambers w/o piling all that crap on top of the valves., also, any idea how often I should tear it down and clean it to this point again? luckily I have six other cars so having the thing sitting around isn't any big deal. (other than all the crap I take about having a car that is always being worked on)...

Thanks for ALL the help and advice.....the website you guys run is fantastic,... I don't know if I ever mentioned it, but I work part time at AutoZone and every time a SHO owner comes in, I recommend the site...

Richard Reeder

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