DEAD 460
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Laughing Gas
Joined: Dec 2004
Posts: 754
Likes: 3
From: Idaho
DEAD 460
I recently purchased 78 supercab mostly for the engine,it ran but a little ruff.So I took it home did all the usual stuff then ran a compression test 138 on all but #8 dead hole! yippie.So wasn't really concerned cause I'm putting dove heads on it. So last night I pulled the offending head and low and behold no burnt valve no hole in the piston no flat cam NOTHING WTF!!!!!!! Haven't checked the rings yet or for a sticky valve,but no scarring in the cylinder .Oh by the way it has an engine builder tag on the front so been rebuilt at some point. It is a D1VE block and D3 heads. Well any Ideas would be helpful at this point. Thanks in advance for any ideas 
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
I recently purchased 78 supercab mostly for the engine, it ran but a little ruff. So I took it home did all the usual stuff then ran a compression test 138 on all but #8 dead hole! yippie. So wasn't really concerned cause I'm putting dove heads on it. So last night I pulled the offending head and low and behold no burnt valve, no hole in the piston, no flat cam...NOTHING WTF!!!!!!! Haven't checked the rings yet or for a sticky valve,but no scarring in the cylinder .Oh by the way it has an engine builder tag on the front so been rebuilt at some point.
It is a D1VE block and D3 heads.
It is a D1VE block and D3 heads.
1971/73 429 Ford/Merc Passenger Cars / 1971/78 460 FoMoCo Passenger Cars & 1973/78 F100/350 / 1975/78 460 E250/350 / Some 1979 460 F150/350 & E250/350.
Logistics Pro
Joined: Jul 2005
Posts: 4,217
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So last night I pulled the offending head and low and behold no burnt valve no hole in the piston no flat cam NOTHING WTF!!!!!!! Haven't checked the rings yet or for a sticky valve,but no scarring in the cylinder .Oh by the way it has an engine builder tag on the front so been rebuilt at some point. It is a D1VE block and D3 heads. Well any Ideas would be helpful at this point. Thanks in advance for any ideas
Junior User
Joined: Nov 2017
Posts: 74
Likes: 1
From: Mokelumne Hill
Alans77, for checking static sealing of valves to seats I simply use parts solvent and do the testing in my solvent washer. I also use a strong LED flashlight and watch the leaks, if any, through the respective ports. You may have some wicking/wet area under the valve seat but you may also have a trickle or free flowing-this is what I mainly concern myself with. Then I chuck up the cleaned up valve in the valve grinder and see if it is bent. You can do the same in a drill chuck for example. I have seen engines that had severe detonation break piston rings but they still had some compression showing on the gauge.
Fleet Mechanic
Joined: Feb 2004
Posts: 1,508
Likes: 332
From: Arlington,Wa
I had the same thing happen to me a few years ago on a 460 i was working on. Had good compression on all cylinders except numero 5....it had zero. Found out there was a short pushrod. Bought 2 new ones that were the same length as the other pushrods and it solved the problem. Hope this helps...
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Laughing Gas
Joined: Dec 2004
Posts: 754
Likes: 3
From: Idaho
Well got busy but did find the problem.could not see it for looking at it, did what you guys said filled the combustion chamber and it leaked broken valve spring in three pieces! dont know I didnt see but damn sure didnt! thanks everyone al
Junior User
Joined: Nov 2017
Posts: 74
Likes: 1
From: Mokelumne Hill
Unless you are on a tight budget, I would think it prudent to replace all valve springs in case any more are getting ready to shake hands with you. You got lucky this go round since you didn't have a dropped valve in the cylinder from the broken spring, tearing up components. That will take a bite out of yer wallet.
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Laughing Gas
Joined: Dec 2004
Posts: 754
Likes: 3
From: Idaho
Its getting dove heads and a new cam kit. yep been down that road before my personal truck had a 400 in it and it broke 4 valve springs in as many months, that's why she has a cummins in it now.this truck is one we are building for my youngest boy. it seems like since I put the cummins in both my boys have been bitten by the dent side's so they both have project sc's 4x4's in the wings, in the past 2 years we have parted 5 roached supercabs for parts for them, should be fun when we have them done!!! Thanks again guys as I said couldn't see it for looking at it!
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