The great debate...
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Joined: Apr 2006
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From: Kansas City, KS
The great debate...
OK guys...351M with unknown miles and at least two bad valves.
Originally, the plan was to limp it til now, pull the heads, get them rebuilt, reinstall and keep on trucking.
The point was made that putting new heads onto an old engine may blow the bottom end out.
So, I changed the plan to limp it til August or so, then do a full rebuild.
Whaddya think? Do I get the heads rebuilt and pray for the best, or do I take the whole thing down? I don't know how many miles are actually on it, it does keep oil pressure fairly well...runs like crap cause one cylinder has zero compression, and one has 60ish. (The other six have between 100 and 110 psi)
What says you?
Originally, the plan was to limp it til now, pull the heads, get them rebuilt, reinstall and keep on trucking.
The point was made that putting new heads onto an old engine may blow the bottom end out.
So, I changed the plan to limp it til August or so, then do a full rebuild.
Whaddya think? Do I get the heads rebuilt and pray for the best, or do I take the whole thing down? I don't know how many miles are actually on it, it does keep oil pressure fairly well...runs like crap cause one cylinder has zero compression, and one has 60ish. (The other six have between 100 and 110 psi)
What says you?
Junior User
Joined: Jun 2006
Posts: 68
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I played this game last year. Blew head gasket and found burned valves on both heads. Replaced both heads and it lasted about a month before I broke a ring on a piston. Now I am doing a full rebuild on my 400. The only advantage was spreading the cost out but the total is much higher in the end.
P.S. This time I am doing it right!
P.S. This time I am doing it right!
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Joined: Jan 2008
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Scrap the 351M go look for a 400 from hopefully a 71 or 72 vehicle
for the crankshaft.
If not, rebuild a 351M to a 400 with the crankshaft for later year 400 to get full value for your money.
Note: checking piston tops on used engines will tell you if that engine has been rebulit of not because they stamp them with .010,.020.030,etc
Spending $2000 on 351M IMO is foolish.
Spending the same on a 400 will increase everything the engine is capable of.
http://home.earthlink.net/~bubbaf250/index.html
http://www.fordcobraengines.com/Modified%20History.htm
for the crankshaft.
If not, rebuild a 351M to a 400 with the crankshaft for later year 400 to get full value for your money.
Note: checking piston tops on used engines will tell you if that engine has been rebulit of not because they stamp them with .010,.020.030,etc
Spending $2000 on 351M IMO is foolish.
Spending the same on a 400 will increase everything the engine is capable of.
http://home.earthlink.net/~bubbaf250/index.html
http://www.fordcobraengines.com/Modified%20History.htm
Last edited by Mil1ion; Mar 27, 2007 at 05:46 PM.
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Joined: Apr 2006
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From: Kansas City, KS
Ooops...I left that part out...if I'm going to rebuild it, I'll rebuild it as a 400. The rebuild kit is only a couple bucks more (including pistons) and I can buy a reman crank for $150.
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From: Kansas City, KS
Crankshaft and pistons....the rest is identical.
The idea is to pull the 351M out, buy a rebuild kit for a 400 that includes pistions, and then buy a crank seperately.
Sounds like I should just tear it down...
The idea is to pull the 351M out, buy a rebuild kit for a 400 that includes pistions, and then buy a crank seperately.
Sounds like I should just tear it down...
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Check with our sponsor Tim Meyers when you price your engine kit out. He will help you decide what upgrades are best for your application and his prices are very competitive for high quality parts.
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Joined: Mar 2005
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From: western montana
also you might find a good deal on a rebuildable 400 and work on it as you can afford to- both time and money. Then it ill be a swap out. I can buy complete 400 for 150 or so...you might need it before august.
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Joined: Apr 2006
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From: Kansas City, KS
Good point Roger, but the truck is a "toy" at this point. If it died tommorow, I'd be plenty mad, but I don't use it much right now anyway...I think I can limp til August when my boy is out here and can help me rebuild it.
Postmaster
Joined: Aug 2001
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From: Delaware
351M/400 cores are as cheap as dirt.
Find a core block or rebuildable 351M/400 and buy the complete kit from TMeyer Inc. Build your motor to the specs you want, not what some rebuilder wants to give you.
In the meantime. drive your truck. When the new short block is ready, get your heads/valves done and swap motors. Then turn your old crank/block in for core charges.
Find a core block or rebuildable 351M/400 and buy the complete kit from TMeyer Inc. Build your motor to the specs you want, not what some rebuilder wants to give you.
In the meantime. drive your truck. When the new short block is ready, get your heads/valves done and swap motors. Then turn your old crank/block in for core charges.
