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400 problems...

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
Alright...thank ya sir. To be honest, it will be about a month and another trip home before I could really dig any further into this. But thanks for the info.
 

blackhat620

You Had to be There
1,687
150
Arizona
Alright...thank ya sir. To be honest, it will be about a month and another trip home before I could really dig any further into this. But thanks for the info.

If you do not have a trans temp gauge you may want to install one before you head home. Would hate to have you overheat the trans.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
If you do not have a trans temp gauge you may want to install one before you head home. Would hate to have you overheat the trans.


Dually noted...worst case scenario, I got a buddy holding a C6 for me that I was keeping as a back up.
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
Yessir I did...
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
Not yet man...took a 2 mile trip to the grocery store and forgot all about it...seeing as I didn't hit 60-70mph on the way...haha. And beyond that been busy with class, hw and interviews.
 
You should invest in a good dial bore gage that reads in .0001 if you don't already have one, so the cylinders, main and rod bearing bores, and bearing clearance can be checked accurately. In a 351M-400 I would want to see at least .0025 and no more than .0032 on a main bearing. No less than .002 not more than .0025 on a rod bearing. No bearing should be tipped more than .0002 edge to edge. You should also use your porting stuff to chamfer the cranks oil holes if it's going to be ran hard.
 
Last edited:

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
You should invest in a good dial bore gage that reads in .0001 if you don't already have one, so the cylinders, main and rod bearing bores, and bearing clearance can be checked accurately. In a 351M-400 I would want to see at least .0025 and no more than .0032 on a main bearing. No less than .002 not more than .0025 on a rod bearing. No bearing should be tipped more than .0002 edge to edge. You should also use your porting stuff to chamfer the cranks oil holes if it's going to be ran hard.


Thanks man...and when considering full rebuilds, I take every precaution necessary...but for the time being, this engine is just meant to be semi-reliable and not have to worry about catastrophic failures. I'm pretty happy with it as is...just had those few questions...and since I'm heading back home tomorrow, I'll re-read this thread and get to work on the fine tuning.
 

DNFXDLI

The Token Canadian
Staff member
Didn't you just have 2 weeks off you part timer?
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
Didn't you just have 2 weeks off you part timer?


Yeah...but I got into the third of 5 rounds of interviews with BB&T. Sooooooo...I'll be heading home for a 2 day office interview.
 

DNFXDLI

The Token Canadian
Staff member
Yeah...but I got into the third of 5 rounds of interviews with BB&T. Sooooooo...I'll be heading home for a 2 day office interview.

Right on Ben!...best of luck to ya!
 

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house

LEB Ben

Arrogant A-hole At-Large
34,919
1,124
outside your house
***update***

1) The biggest problem of all is, there seems to be a backfiring issue. It's not a consistent problem, but it seems to happen most often when I let off the gas to coast or slow down, then when I go to get back on the throttle I get pop/backfire and then it'll accelerate. It also seems to happen at shift changes as well. It's worse when the vehicle is cold, but as I said...the problem is not consistent at all..

Went back and put a little more effort into fine tuning the carb and advanced timing a tad...problem done

2) When traveling at sub 35mph speeds, and I go to give it a little bit of gas, it will sputter/stutter a little bit and then resume properly...not that big of a deal...just more of an annoyance..

Fine tuning the carb, all but eliminated this as well...as suggested, a carb rebuild will more than likely fix it. But it seems to be 95% of the way there.

3) There have been 5 times now in about 500 miles of driving where I will start the vehicle and start driving and after a few hundred feet the vehicle will die. It's almost like it's using whatever fuel is in the bowl, and then like there was no fuel in the outlet line from the fuel pump..

In the last 1000 miles, it still did this once, but hopefully a rebuild will eliminate this as well.

4) I've noticed a new vibration...or wobble rather...that wasn't there with the old engine between 60-70mph. Not sure if this is engine related, but it wasn't there until the swap..

I paid more attention to this issue. On the way home, it happened from 63-69mph, and would happen around 2-2300rpm. At home, I retorqued every bolt I could find, and did a tranny fluid change. On the drive back up here, it was waaaaaaaaay less noticeable, but still there. Although, I did notice that it seemed to correlate with how hot or cool the rig was running.

5) Now I know these things aren't gas sippers, and I'm not complaining...I just made an observation, that could possibly be attributed to any of the above problems. The old, tired, worn out 351M would get 10mpg city and 14mpg hwy...the new 400 get's about 7 and 9.5. I just really didn't expect such a big drop in mpg's going from a bad engine to a good one.

After some fine tuning, it would appear as if I picked up 1mpg city and .5 mpg highway. Again, I hope a rebuild will improved these numbers as well.
 

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