Junkyard engine build
Thread Starter
|
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
Junkyard engine build
Believe it or not, my 390 is still going, but it's not going to be long before something lets go in it- the misfire it has is getting noticeably worse, and the gas is still finding it's way into the oil. It sounds like the engine in Patrick McManus' mountain car, "like a washing machine falling down a flight of stairs!" -Something tells me that isn't good! 
Here's my problem: I don't have the money to rebuild this engine. The subject of replacing the truck with a 1999 Taurus has been coming up lately, so I need to get this truck running and reliable. So, I've been thinking about cobbling together a motor from whatever decent parts I can find at the local yards, throwing a few new parts into it, and hitting the road. If the parts are good, I don't see any reason why not.
Here's my question: once a head has been pulled from a motor, how do I tell if it's any good?
Sam
Here's my problem: I don't have the money to rebuild this engine. The subject of replacing the truck with a 1999 Taurus has been coming up lately, so I need to get this truck running and reliable. So, I've been thinking about cobbling together a motor from whatever decent parts I can find at the local yards, throwing a few new parts into it, and hitting the road. If the parts are good, I don't see any reason why not.
Here's my question: once a head has been pulled from a motor, how do I tell if it's any good?
Sam
Posting Guru
Joined: Dec 2010
Posts: 1,240
Likes: 2
From: Chino Hills
There would be a ridge on the last 1/4 of the bore.
As you drag your finger up from lower in the cylinder bore you will feel a bump at the last 1/4 inch. If you feel to much of a bumb the motor needs a re-bore.
As you drag your finger up from lower in the cylinder bore you will feel a bump at the last 1/4 inch. If you feel to much of a bumb the motor needs a re-bore.
Thread Starter
|
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
Thanks, what about cylinder heads?
I've heard if the seats and valve faces are nice and shiny that's a good sign, big carbon deposits on the springs and guides would probably be something to avoid, anything else to look for?
Sam
I've heard if the seats and valve faces are nice and shiny that's a good sign, big carbon deposits on the springs and guides would probably be something to avoid, anything else to look for?
Sam
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
Pull the plugs for a look, smell the oil on the dipstick for blowby, look at the underside of the oil cap for sludge. When you unbolt the rocker shaft, check the ball end of the pushrod for a wear ridge. Look at the valve margins around the edge of the valve, do the valves seem to sit high above the seats?
I've seen good assemblies go to the crusher when scrap prices were up. Happy hunting!
P.S. I'll see if I have any Taurus wagon pictures still hosted. I've fit some unlikely things in the back of the ol' battle wagon.
I've seen good assemblies go to the crusher when scrap prices were up. Happy hunting!
P.S. I'll see if I have any Taurus wagon pictures still hosted. I've fit some unlikely things in the back of the ol' battle wagon.
Thread Starter
|
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
I'll keep those in mind, thanks! The sad thing about the local yards here is none of them hang onto their trucks for very long before they meet the crusher, the upside is there's always new trucks to pick over!
You should've seen some of the stuff the stuff we've had in my dad's hatchback focus, we had some deck lumber in there once, one end was sitting on the dash- one hard stop would've sent the whole mess through the front windshield! My uncle had another idea when he hauled some 8 foot 2x4s home in his Lexus -he opened the sunroof and stuck them through! 
Sam
You should've seen some of the stuff the stuff we've had in my dad's hatchback focus, we had some deck lumber in there once, one end was sitting on the dash- one hard stop would've sent the whole mess through the front windshield! My uncle had another idea when he hauled some 8 foot 2x4s home in his Lexus -he opened the sunroof and stuck them through!
Sam
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 420
From: Long Island USA
For heads, pour light machine oil (like marvel mystery oil) into the ports and see if it runs out past the valve and seat. And of course, if they are generally clean but not TOO clean (indicating they have been cleaned by the junkyard). And check if the valve seals are still there 
Posting Guru
Joined: Dec 2010
Posts: 1,240
Likes: 2
From: Chino Hills
A cheap way to check the heads is to clean them up really good and pour gas into eachport and see if it leaks past the valve.
If there is a little drop or drip they will be fine for quite awhile to make it worth it anyways.
If you have a valve spring compressor you can pull them apart, and clean by hand if you want too. Just becarefull to put the shim back into place.
Trending Topics
Thread Starter
|
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
Ok, will do! I'll have to open the motors up myself, so I should be able to get a good look inside. There's usually 6 or 7 FEs out in their yard, at least one set of heads should be decent.
And the heads are the same both sides right? Should I get both heads off the same motor or would it hurt to mix and match?
Sam
P.S. I just called the local yard and they said $50 a head, now that sounds like something that fits my budget!
And the heads are the same both sides right? Should I get both heads off the same motor or would it hurt to mix and match?
Sam
P.S. I just called the local yard and they said $50 a head, now that sounds like something that fits my budget!
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Ford Super Duty: 5 Things Owners LOVE, 5 Things They LOATHE!
Joe Kucinski
Every 2026 Ford Truck Engine RANKED from WORST to FIRST!
Michael S. Palmer
The Best F-150 Deal of Every Trim Level (XL through Raptor)
Joe Kucinski
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 420
From: Long Island USA
Junior User
Joined: Sep 2007
Posts: 92
Likes: 0
From: BFE
Get yourself an engine manual and learn it for yourself. It's really the only way you'll "get it". Besides, you can learn at your own pace and it is knowledge you can use on other engines as well. Once you learn the basics of fuel & exhaust, engine electrical, cooling and oiling you're well on your way. It's fun too!
Thread Starter
|
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
It is fun, nothing like tearing into a motor! I had this motor all apart before, and there's nothing like the feeling you get when the thing is put back together and starts for the first time!
We'll see how this junkyard build works out for me, I'm pretty confident I can find decent heads, but I may have to get a core short block and do some work to it. Rings are no big deal, provided it needs just a hone. It's the bearings and rod's that worry me.
Is there any way to identify rod knock/wrist pin knock by just by plasti-gauging the bearings and seeing if everything is tight?
I'd just like to make sure I get all my bases covered, the last thing I need is to have this thing loose a rod and toast the block!
Sam
We'll see how this junkyard build works out for me, I'm pretty confident I can find decent heads, but I may have to get a core short block and do some work to it. Rings are no big deal, provided it needs just a hone. It's the bearings and rod's that worry me.
Is there any way to identify rod knock/wrist pin knock by just by plasti-gauging the bearings and seeing if everything is tight?
I'd just like to make sure I get all my bases covered, the last thing I need is to have this thing loose a rod and toast the block!
Sam
Posting Guru
Joined: Dec 2010
Posts: 1,240
Likes: 2
From: Chino Hills
Yes you can use plasti guage to check rod/main bearing clearances.
But I would pop the caps off and if they look fine they are. A slightly polished/matte look is what to look for. Bearings are such soft metal that they will tell you if there hurt.
Heads are interchangeable from side to side
But I would pop the caps off and if they look fine they are. A slightly polished/matte look is what to look for. Bearings are such soft metal that they will tell you if there hurt.
Heads are interchangeable from side to side
Cargo Master
Joined: Apr 2004
Posts: 2,574
Likes: 4
From: Golden, CO
I doubt you'll have to mix and match heads, they seem to wear at the same rate.
When my wrist pin was going, I found sparkles in the oil when I drained it. I didn't look, but I'm sure there were plenty of shavings left in the bottom of the oil pan. There is always a little oil and debris trapped in the pan.
When my wrist pin was going, I found sparkles in the oil when I drained it. I didn't look, but I'm sure there were plenty of shavings left in the bottom of the oil pan. There is always a little oil and debris trapped in the pan.
Senior User
Joined: Jun 2004
Posts: 455
Likes: 0
If the motor has any serious looking exhaust leaks at the manifolds you could have damaged exhaust valves. Look around the block near the mount areas for a rebuilder tag that may give some sign of hope. poke around gloveboxes for any maintenance history or rebuild work.
Thread Starter
|
Fleet Mechanic
Joined: Aug 2009
Posts: 1,771
Likes: 9
From: Western Washington
Ok, thanks. I'll have to get dad to take me out to the yards sometime soon, maybe this weekend. We'll see if there's anything worth bringing home. Thanks for the tips on the wrist pin and the exhaust leaks, wrist pins was one of my biggest worries.
Sam
Sam
Thread
Thread Starter
Forum
Replies
Last Post
Curtis McCarty
1987 - 1996 F150 & Larger F-Series Trucks
6
Jul 21, 2015 02:02 AM
facelessnumber
Clutch, Transmission, Differential, Axle & Transfer Case
12
Jun 16, 2013 09:12 AM
cwatkin
1980 - 1986 Bullnose F100, F150 & Larger F-Series Trucks
6
Feb 22, 2012 10:19 AM
