Input needed on 400
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Senior User
Joined: Feb 2004
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From: So. La.
Input needed on 400
I'm the proud owner of a new (used) 1979 Bronco w/ 400 cid (C6, NP203 converted to part time).
I'm looking for input on the operational characteristics of this engine, ya know, what it likes, doesn't like and how it misbehaves, etc.
Right now, I've got an oil leak from the back of the engine/bell housing area - oil pools immediately when you stop. Some times worse than others.
The previous owner mentioned that "it had a small leak at one of the valve covers per as usual for this engine". It didn't leak after the test drive, of course. In all fairness to him, his brother was the last to use this vehicle so he (brother) could have worsened the problem thru adverse driving habits (LOL).
Your help will be greatly appreciated
I'm looking for input on the operational characteristics of this engine, ya know, what it likes, doesn't like and how it misbehaves, etc.
Right now, I've got an oil leak from the back of the engine/bell housing area - oil pools immediately when you stop. Some times worse than others.
The previous owner mentioned that "it had a small leak at one of the valve covers per as usual for this engine". It didn't leak after the test drive, of course. In all fairness to him, his brother was the last to use this vehicle so he (brother) could have worsened the problem thru adverse driving habits (LOL).
Your help will be greatly appreciated
Postmaster
Joined: Jun 2003
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From: WA
the biggest issue is low oil pressure when hot. A sign of worn bearings. Other than that they ar pretty innefficient, but durable engines! They like cams that are long on the exhaust side. They like headers.
Post Fiend
Joined: Mar 2005
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From: Louisiana
I'm the son of grey77 and I bought the truck, and I will be putting headers, doul exhaust, and eventually a 4bl carb (around 600 cfm) but you also said cams, did you put a came in yours? What kind, how much the cam cost, and how much did it cost to put the cam in?
Oh and what would be a normal oil pressure to run at, on the 4 hr drive home the oil pressure was around 25 -30?
Thanks for the tips
Oh and what would be a normal oil pressure to run at, on the 4 hr drive home the oil pressure was around 25 -30?
Thanks for the tips
Postmaster
Joined: Jun 2003
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From: WA
I am using a comp cams 265DEH. If you want pure low end grunt, the 255DEH is your pick. Cam runs around 125$, plus the matching springs. You can swap it in the truck, but will have to pull the water pump, fan, radiator. I dont know the shop rate to swap it.
Pressure while driving is usually around 55psi.
Pressure while driving is usually around 55psi.
Junior User
Joined: Dec 2003
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From: Kalispell,Montana
Beeboy, I've been looking into the 265 DEh cam,and wondering if the stock pushrods work with it or if new ones are warranted. A previous reply indicated low oil pressure at operating temps,a sign of worn main bearings.My truck has been in the family since new,and my wifes grandpa said that about 20000 miles after he bought truck he had a recall on it for main bearings which were replaced.I realize that 120,000 miles later the bearings may be shot again but I am experiencing the same low oil pressure at operating temps and especially at idle as described above.Other than that truck doesn't use oil and really scoots with the new 4 bbl and manifold,mileage dropped from 10 mpg to 6 mpg,but still have some tuning to do. Any thoughts? Thanks, John
Posting Guru
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From: KY
400 engine
The oil pressure drop is most likely from the block. I mentioned it in the other section on Bronco's. 8 out 10 of these engines would crack around the lifter and cam gallies. Bad blocks. I am a die hard ford man but over the years I have figured out that Ford could cast a rod and reel much less a block or a head.The oil leak, like you say, could be valve cover but I have seen rear main caps mistaken for rear main leaks. When you put the rear main cap on the mating surface between the cap and the block should be sealed with anarobic sealant. It takes a very thin film and will not effect bearing crush. Take it easy
Postmaster
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From: WA
John, its not uncommon for these blocks to last forever, even with low oil pressure.
Here is a good article on these engines for you.
http://www.projectbronco.com/Technic...the_rumors.htm
Here is a good article on these engines for you.
http://www.projectbronco.com/Technic...the_rumors.htm
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Thread Starter
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Senior User
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From: So. La.
Went around both valve covers & oil pan snugging-up bolts, then ran it agiain. Oil weak has been "slower" or "less", but still there. Went to the car wash and cleaned suspected area.
Found one bolt on oil pan that is wet, in fact oil drops form on it.
Next, majority of oil leaking from where oil pan and front of transmission meet - main seal area.
So, I figure my next move is to drop the oil pan, check the main seal & shaft for scoring. If that's OK, regasket w/ sealant (what would be best sealant to use, specifically?) for gasket and bolts.
Unless someone has a more informed idea ?
Found one bolt on oil pan that is wet, in fact oil drops form on it.
Next, majority of oil leaking from where oil pan and front of transmission meet - main seal area.
So, I figure my next move is to drop the oil pan, check the main seal & shaft for scoring. If that's OK, regasket w/ sealant (what would be best sealant to use, specifically?) for gasket and bolts.
Unless someone has a more informed idea ?
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Posting Guru
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From: PacNW
8 out of 10 of these blocks would crack??? Hmm...an 80% failure rate? I don't think so! 
Blocks cast at the Michigan Casting Center (MCC) prior to March 1, 1977 (casting date 7C01) were prone to cracking in the lifter valley. However, many 351M/400 blocks were cast in the Cleveland Foundry (CF) and many of the earlier year 400 blocks were cast in the Dearborn Iron Foundry (DIF). None of these blocks had that problem.
It does pay to check casting dates & foundry codes when working with the 351M/400 especially if you plan to sink some $$$ into a rebuild.
The oil pressure sending units on these engines are notorious for leaking. Since it's on the back of the block it looks alot like a rear main. It's relatively easy to change and still available from Ford. That would be the first thing I'd check after I verified the valve covers were tight.
Blocks cast at the Michigan Casting Center (MCC) prior to March 1, 1977 (casting date 7C01) were prone to cracking in the lifter valley. However, many 351M/400 blocks were cast in the Cleveland Foundry (CF) and many of the earlier year 400 blocks were cast in the Dearborn Iron Foundry (DIF). None of these blocks had that problem.
It does pay to check casting dates & foundry codes when working with the 351M/400 especially if you plan to sink some $$$ into a rebuild.
The oil pressure sending units on these engines are notorious for leaking. Since it's on the back of the block it looks alot like a rear main. It's relatively easy to change and still available from Ford. That would be the first thing I'd check after I verified the valve covers were tight.
Last edited by Bill_Beyer; Apr 6, 2005 at 08:56 AM.
Postmaster
Joined: Jun 2003
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From: WA
MBB. Look at the comp 255DEH.
Some good advice in this thread
https://www.ford-trucks.com/forums/s...5&pagenumber=1
Some good advice in this thread
https://www.ford-trucks.com/forums/s...5&pagenumber=1