A little story about buyer beware....

[Onequick26]

So A buddy of mine finds a good deal on a 75 F-100 4x4 here in town.
It's a short box big block (390) truck. He buys the truck and it runs but has some carb problems he tells me. He messes around with it a bit for a few days... I get the call.. Can I bring it to you shop to look at it, I tell him sure no problem..The guy he got it from tells him it's got a newer cam it. I get to messing around with it and this is what I find ! We all know this did not happen over night .....

 

[sgtpontiac]

Well he didn't say how new???

So A buddy of mine finds a good deal on a 75 F-100 4x4 here in town.
It's a short box big block (390) truck. He buys the truck and it runs but has some carb problems he tells me. He messes around with it a bit for a few days... I get the call.. Can I bring it to you shop to look at it, I tell him sure no problem..The guy he got it from tells him it's got a newer cam it. I get to messing around with it and this is what I find ! We all know this did not happen over night .....

Maybe it was two years new....lol Obviously the guy who bought the truck is not a wrench? Man that thing must have been running like crap....bad deal....where is all that metal gone?? Oh boy!

 

[Willowbilly3]

Yikes!! Over revving and no cam break in would be my guess. Not too bad a fix if that's all that's wrong. I'd bet 50-50 odds it's a 360. They all somehow turn to 390s after a few years,lol.

 

[Sam_Fear]

Wow! Took me a second to even catch on to what that first pic was! That is ugly.

And WB is right, it's probably one of the magical 390's.

 

[hotrod preacher]

MANY low milage cams wind up looking like that because of improper assembly and no break in time... the guy may not have had a clue that a new cam could be doing that... just a thought...also remember that Fe engines have no adjustment on rockers... and clearances must be checked when changing cam sizes or problems can happen as well


also a little FE trivia
the pistons should come "al the way to the top" if it is a true 390...

360 pistons are .100" "down the hole"

crank casting 2U or 2UA for 390...... 2T for 360
pistons can even say "390 4V" and it be a 360...

 

[donsrods]

That cam could have failed in the break in period. I bought a Camaro ex drag car that only had break in time on it and had never moved under it's own power. When I tore the motor down one lobe and lifter looked exactly like the ones you pictured.

Flat tappet cams are becoming a real problem since they pulled a lot of the zinc out of oil. I am running a roller cam and so is my Son Don, but Dan has a flat tappet cam in his 455 Olds and we took GREAT pains to break it in right. We are still running Lucas Break in oil in the motor and will continue to dump in half a can with every oil change.

That motor could be a recent rebuild but a lot of people think you just start them up with oil in the pan and let it idle while you fiddle with the tuning. Quickest way to kill a cam.

Don

 

[rex1927]

WOW!
Thats a beat up cam.And those pushrods!!!

 

[rainman]

Agree with the above, probably was new, improperly broken in!!
Now days you have to use a zinc additive, some people don't know this!!

 

[Old Iron]

Too eager to hear the rumpity rump at idle is an illness spread by inexperience and usually cured by geedus.

 

[Neverdone]

My buddy put a crane cam in his truck (Chevy 454) and had that happen. Broke in correctly and all. Pulled the cam and sent it back to crane. They stress teated it and determined it was THEIR FAULT!!. They cut him a check for a new motor!!

 

[Willowbilly3]

MANY low milage cams wind up looking like that because of improper assembly and no break in time... the guy may not have had a clue that a new cam could be doing that... just a thought...also remember that Fe engines have no adjustment on rockers... and clearances must be checked when changing cam sizes or problems can happen as well


also a little FE trivia
the pistons should come "al the way to the top" if it is a true 390...

360 pistons are .100" "down the hole"

crank casting 2U or 2UA for 390...... 2T for 360
pistons can even say "390 4V" and it be a 360...

Dowel test will tell you, 360 is about 3.5 and 390 is about 3.75 (3.48 and 3.78 iirc). I could be wrong but I think both engines are pretty close to the same compression height since they both have about the same static compression within the same years of pickup trucks and the heads were identical.

 

[donsrods]

What is weird is in the old days we slipped in a new cam, let it idle for a while, then drove off into the sunset. I did it a bunch of times and never had a problem. Even recently, I had an 84 Ford with a non roller cam 302 and never ran additive and never had a cam problem. I drove that car daily for 6 years. Makes me wonder if the cams today are being made from a different metal or what. I know the zinc thing is a biggie, but can that be all there is to the problem?

Don

 

[Onequick26]

The new cam came in this morn. Gona put her back together this weekend . Oh and it dose turn out to be a 360.

 

[Onequick26]

Dowel test will tell you, 360 is about 3.5 and 390 is about 3.75 (3.48 and 3.78 iirc). I could be wrong but I think both engines are pretty close to the same compression height since they both have about the same static compression within the same years of pickup trucks and the heads were identical.

Thanks for the info !!![cl

 

[donsrods]

Scrub and clean that block and all the parts super good, all those metal shavings went somewhere. I would start it, run it at 2000 rpms for half an hour, with zinc additive, then change the oil immediately and put new oil and zinc in it again.

Don

 

[Willowbilly3]

I've heard the better diesel oils still have zinc and moly, like Dello 400 and Rotella.

 

[sgtpontiac]

Yep....know for sure Rotella does...

either way, I stock some ZDDP for oil changes on the 63 and the pickup......then I don't worry about it....goes in every change regardless of the oil I am using......wouldn't fire a non roller cam motor..(ah Engine) without it....LOL...

 

[donsrods]

I called Lucas when we were breaking in my Kid's Olds engine to ask about their Break in Additive, and the guy there said run a full bottle for the first 1000 miles, then change it and add half a bottle every oil change from then on. We went one better and pulled the first batch of oil right after the first half hour break in, and it was getting black from cleaning out the newly machined block. We then loaded it with fresh oil and a whole bottle of Break in Additive, which we will leave in for the first 1000 miles. This time the oil is staying pretty clean.

It costs a little more to do it this way but sure is cheaper than bearings and cams.

Don

 

[hotrod preacher]

Dowel test will tell you, 360 is about 3.5 and 390 is about 3.75 (3.48 and 3.78 iirc). I could be wrong but I think both engines are pretty close to the same compression height since they both have about the same static compression within the same years of pickup trucks and the heads were identical.

the 360's we tore apart used 390 4v pistons, (flat-top w/ eyebrows) and a 352 crank and rods...and the pistons were .100 lower than a 390 at tdc... compression was different on the 390's b/c most of them used a slightly dished piston... the 390 with a 4v piston (not available in a truck) pushed compression closer to 10 to 1...

 

[Onequick26]

It's alive !!! She fired right up,ran it for about 15mins @ 2k ....Then the bottom tank blew on the radiator .... But it ran like a champ for being an old wore out engine.