#4 exhaust valve




#4 exhaust rocker


Hi guys,
Just figured out how to make a new thread sorry I'm a noob here.

Here's the situation: I had a new 390 built for the 72 f250 C6 2WD CS Been runnin great no trouble. I drive 2.5 miles to work in it and around town to get supplies so mostly city driving. The other day I was coming up to a stop light and it started missing real bad so I checked it out and #4 was dead. I took the valve cover off and the valves were moving and it was getting spark. Vac guage was reading low and jumping around from 9 to 11 in Hg at idle. Full vac on throttle shutdown was around 18 in Hg. normally about 23 in Hg. Did some reading and figured it must be a burnt valve. Mind you this motor has about 2000 mi on it. So I'm driving it back to the barn to continue investigating the issue and she gets about 2 blocks from the house and starts cackling and raising all kinds of hell. Remove valve cover and the #4 rocker and shaft fall on the floor. WTF over? Push rod is bent and come to find out the double valve springs had the outside heavy spring broken( wish I would have caught that) Tore it down popped off the head and the valve is not bent as far as I can tell. This motor is new. Would a broken valve spring cause all that? Is this a warranty issue ? I think so. It was properly broke in and ran like a stripped *** ape till it took a dump. My builder is in Redding and I'm in San Francisco so getting it back to him to fix is out of the question. Is there any thing else I should look for as the cause or just suck it up and put in a new rocker shaft, valve spring, push rod and drive it up there and shove it up his bum. Sorry but I'm a little more than pissed right now seeing as this clown took a year and a half to build the damn thing, overcharged me 500.00 cause he can't keep his paperwork straight, then he painted it black, on a 72 WTF again.

 

The broken valve spring could cause that by binding up and not allowing the valve to open. That would cause the bent pushrod and/or broken rocker shaft. Were the rocker assemblies new or cleaned reused? I am not going to hazard a warranty guess, but it would be worth a phone call, nicely, to let him know what happened and ask how he will handle it. That sucks to have an issue like this.

 

A few thoughts...

-Those aren't dual valve springs, those are single spring with dampner.

-That rocker shaft broke right where the stud/bolt attaches it to the head, there is a procedure for torquing down those bolts. Failure to do it properly could bend/make a crack in an otherwise good rocker shaft. I suspect there may have been a small stress crack for some time and it most likely just finally gave way.

-If the mechanic screwed up the engine in the first place, I'd hate to consider having to take it back to him.

-I'd also make sure the valve guide clearance is good, even if the valve is straight it may have bound some in the head, tho normally this just results in a bent pushrod.

either way, sorry for your troubles and good luck.
Drew

 

check pushrod length, should br 9.59" . what cam are you useing? if its a high lift you may have had coil bind where the spring is completely closed at total lift. who was your builder as I live near redding. ca. I do not want to use him for my machine work.
Bill

 

Not knowing what valve springs were used but looking at the picture they seem to have three coils close together at the bottom, the broken one has those at the top like it was installed upside down compared to the rest?

 

i would let that re-builder know it failed and have him send you the replacement parts . I wouldn't let him fix it , just chalk it up as lesson learned and do the fix your self or find someone new .

 

You are not alone.

I found this post yesterday after i have just had to deal with the same problem. Its a known issue with higher RPM'S, stonger springs and larger lift cams. I doubt the spring caused the broken shaft. I caught this one before it actually broke going down the track. I noticed a tap that was valve train speed and dug into it. It was the ex valve on the #1 cylinder. Fixed and ready to run for tonights pull. I was lucky i had a spare pushrod, and shafts. Looks like i need to order a few more pushrods. these shafts have been used in the same pulling engine for about 4 years now, so i can' complain much.

[img=http://s30.postimg.org/grlftz5bh/rocker_shaft.jpg]

 

Heavy duty, thick wall shafts are available from several manufacturers, it might be money well spent to upgrade to them. I also broke a stock shaft years ago, no problems after going to the better shafts. End support stands are also out there to wrap around the end of the outside rocker and hold the shaft. Check out Precision Oil Pumps or Oregon Cam Grinders.

 

Well guys here we go again with this 390. I got a hold of my builder and he said they were 428 springs and he was glad I got a hold of him because I might have gotten the wrong springs.(bare that in mind when you read the second paragraph) He said he would get the springs ordered and get them to me asap. I gave him a week for shipping and a week to get them to me. No Show, good thing I wasn't holding my breath. I'm in SF and he's in Redding. I have to have my mom go by at 6:30 in the morning to catch this clown at his shop and he hands over a couple valve springs and 8 push rods and no rocker shaft. I call up Rocker Arms Unlimited also in Redding and he Knows my builder and was actually the guy that got a hold of my builder and let him know he has a warranty issue as this clown does not have an answering machine or voice mail. I make arrangements with The Guy at Rocker Arms Unlimited to have my mom go by at lunch to get my new F88's. He said he had not sold any to my builder in a while so I said give me a matching set and I'll pay the bill. Mom gets there and he was so nice to her she was very pleased with the service at Rocker Arms Unlimited. He helped her box it all up and get it safe to ship and said don't worry about the bill he would make sure my builder would pay the entire bill and apologized for my builders mistreatment as he knows him quite well. I can't say enough good things about Rocker Arms Unlimited The old guy there is Top Drawer.
Now for the bad part. I put the valve spring on and this spring winds the other direction. WTF!?? It's too late to do anything about it now I have to haul a load of lumber in it tomorrow. What difference is there in springs that some would wind the other way? Did he just grab some crap off the shelf? Mom said he had that trapped in the headlights look when she showed up to get the springs so I would imagine he forgot the whole affair.
I have purposely left out the name of my builder because I don't want libel or defame. Besides I'm sure we have young ones and girls on here and they don't need to read that kind of swearing. I think it's time to go to small claims court and get my money back. I'm all for giving a guy a chance to make things right but this is out of hand.
How much danger of ruining my motor am I in by driving it with "The Mystery Spring"? This truck is my Bread and Butter I can't afford to be without it. In the photo below we are looking at the #4 exhaust valve with the new spring installed. He gave me an extra spring, that's the one next to the broken one.
Super Thumbs up For Mom she trooped it out and drove those parts down to Sacramento to meet me at the train so I could skip Bay area traffic and We got to have dinner too. I was back at the barn by 9:30 and so was she.


390 or 428 valve spring??

 

Rent a truck till you get this sorted out. Many times a broken spring will drop the valve, and there goes the piston and head, and if you are really lucky the rod and block.

 

Direction of the wind shouldn't make a difference but I don't know which is correct and I'd be more worried about the other 15. Not knowing which or either of them is correct I would replace all of them with ones you know are correct.

 

I would not use the truck until you get a matched set of correct springs for your camshaft and installed spring height. A set of springs and retainers, if needed , is much cheaper than damaging the block, or head, or piston, or all of them by using an unknown part(s). JMHO

 

Check out this article. It was posted by SoCalRefugee on the thread in this forum about Shorty Headers. They mention how to prevent a broken rocker shaft.
Ford 390 FE - Car Craft Magazine
It's in the paragraph about cam and valvetrain

 

Here is a pic of the rocker shafts end stands

 

Were the shafts new? As stated, it's a known weak spot on FEs