Hello guys, I haven't been on in awhile so thought I'd tell what happened the other day. A couple of weeks ago I decided to take my 71 F250 4x4 out for a drive through the Black Hills and see the sights. Everything was really running great, the truck ran good all day, until I was about a mile away from the pavement, when all of a sudden the motor started sounding like a popcorn machine and missing real bad. I didn't have many tools with me, so we limped home (about 50 miles) coughing and sputtering all the way. The next day I found out that two screws from the bottom of the carb had worked loose and fell down the intake going through the valves. I haven't tore the engine down yet to see the damage it caused but it's got to be fairly major. I'm sure it ruined the valves and probably the pistons. I hope the heads themselves are OK and rebuildable. The oil didn't seem to have gas in it so I don't think the pistons have a hole in them but they are probably shot. Right now I'm thinking of getting a rebuilt engine or maybe a used one if I can find one (390 or 360) or maybe rebuilding this one. I'll keep posting updates here when I decide which way to go. Either way I ought to be pretty busy for awhile!
I'd do a compression check to see if and where the damage is, then pull that head and see if it's just a valve that got bent or a trashed piston / rod assy. If it isn't knocking then it's probably just a valve that got bent.
I'm still waiting to hear back on this "new" engine. I should find out by the end of the week, I hope. In the mean time I'm pacing back and forth, and wringing my hands.
Well I'm still waiting to hear back on the "new" motor. I really hate 3rd party deals! Hopefully I'll find out something this weekend. In the mean time we got the truck ready to switch engines, towed over to a friends house and pulled the front clip. It's going to be alot easier pulling the motor this way than the way I did it last time. I'm too old and fat to crawl into the engine compartment to undo everything, 30 years ago I fit in there pretty good. Now almost everything is right in front of me at waist high, that should save the old back and knees. Now if I just would find out about that motor...
The only screws I can think of is the butterfly screws. If so they are small and brass, I doubt they did any more damage than closing the spark plugs. I have tore down engines with the imprint of much bigger screws into the top of the head, from some long past fod.
I agree to do a compression test, screw in a couple new plugs and fire it up. And get rid of that carb if someone has been messing with the butterflys. If they didn't stake those screws back down then what else did they miss. Also seems odd that 2 screws came out at the same time.
I'm am thinking the screws might have been gone a long time and you have some other problem.
Great ideas have always encounter violent opposition from mediocre minds.
willowbilly3 wrote:The only screws I can think of is the butterfly screws. If so they are small and brass, I doubt they did any more damage than closing the spark plugs. I have tore down engines with the imprint of much bigger screws into the top of the head, from some long past fod.
I agree to do a compression test, screw in a couple new plugs and fire it up. And get rid of that carb if someone has been messing with the butterflys. If they didn't stake those screws back down then what else did they miss. Also seems odd that 2 screws came out at the same time.
I'm am thinking the screws might have been gone a long time and you have some other problem.
It's too early to start pulling that engine, it might not be a serious problem.
The two screws that were missing were from the bottom of the 4 barrel carb. I had never taken the carb off. I think there was 6 screws about an inch long, three were stripped out and two had worked loose and fell down the intake. I'll be putting on my 2 barrel intake and carb I saved from the original 360, I'm saving the old 390 and will probably rebuild it for the next project. Anyway, today I finally found out that the engine is definitely a new long block, now I'm just waiting to find out when I can pick it up. The shop where they are stored is 60 or 70 miles from my house and everything is arranged through a 3rd party so it takes awhile to coordinate.
Also, anyone got any tips on installing the intake gaskets? The last one I did (many years ago) leaked like a sieve! What kind of gaskets are the best, where and how much RTV sealant to use (if any). I have to go to work now so it'll be a couple of days before get back. Thanks!
The screws might not have been on that carb when it was first put on. When I bought by H*lley it was missing the center screws from the get go.
I don't think those screws could fall in the intake, if they worked loose they'd hit the intake manifold and just stay there 'till the next time the carb comes off.
Of course, I'm thinking stock 4bbl intake here.
Everything was really running great, the truck ran good all day, until I was about a mile away from the pavement, when all of a sudden the motor started sounding like a popcorn machine and missing real bad. 
I didn't have many tools with me, so we limped home (about 50 miles) coughing and sputtering all the way. The next day I found out that two screws from the bottom of the carb had worked loose and fell down the intake going through the valves. 
S
that just sucks! 
In the mean time I'm pacing back and forth, and wringing my hands.
Hopefully I'll find out something this weekend. In the mean time we got the truck ready to switch engines, towed over to a friends house and pulled the front clip. It's going to be alot easier pulling the motor this way than the way I did it last time. I'm too old and fat to crawl into the engine compartment to undo everything, 30 years ago I fit in there pretty good. 
Now almost everything is right in front of me at waist high, that should save the old back and knees. Now if I just would find out about that motor...
