The 352 in my 66 f250 is on the verge of crapping out. I purchased a 390 to replace it. After the machining I'm not quite sure if the bearings are too tight on a few of the rods. Below are what plasti guage readings are.
Mains
1. .002
2. .0015
3. .002
4. .0015
5. .0015
Rods
1. .0015
2. .0015
3. .0015
4. .0015
5. .001
6. .0015
7. .002
8. .001

This is the first time I have done an engine in this kind of detail myself. Are the bearings OK in their range or do I need to swap out some of the bearings for a different size?

The end play was .008 on both sides of the thrust bearing.

The deck clearance is .003

I had the heads rebuilt and they were also milled. Plus I ported the intake and will do the exhaust when I am ready to put headers on it. I still need to CC the heads to get the compression ratio. The current head gasket is .062 thickness.

The block had to be bored out .060. Sleeved the oil galley milled decks square to mainline. Line honed the main saddle. Reconditioned the rods. Ground the crank .030/.030 or something like that to get it back to round. I also had the rotating assembly balanced after I assembled the new pistons. Plus I am changing it to a 4bbl with an RV can along with a high volume oil pump and swapping it to an electronic ignition.

I have ben taking my time with this engine and want to do it right the first time as this is my daily driver and may see a few passes at the track this summer. Any suggestions would be greatly appriciated.

 

I have used plastiguage to measure clearences as you have. What you can do is swap the bearing shells around from the one with more clearence to the one with the least and re-measure. Sometimes the bearing shells can vary enough that you will have this varience in clearences. How many times did you check each rod and main?

Ford specs. that I found are 0.0005-0.0015 for the main bearings and 0.0008-0.0015 for the rods. You show some that some that are as much as 0.002 of an inch. This is not excessive as long as you have a good oil pump. A high volume pump will provide the "cushon" of oil that this slightly larger clearence will need.

 

I have just checked 1 time so far.

On the mains the ones that are .002 were actually between .002 and .0015 probably closer to .0017.

So if I understand correctly it is possible to say switch the bearings on say rod #5 and #7 could change the clearances?

Is it normal for a ford engine to be difficult to turn over by hand? Right now it takes a bit of umph to start the rotating assembly to move by hand but once its moving it does not take anywhere the force to turn it over by hand.

I have the rods in the correct position but does it matter which direction they face for the side clearance?

Trying to think of other things to check last thing I want is to spin a bearing or throw a rod. I've had a piston disinegrate before in the 289 on the 65 mustang but it looked like a valve had stuck open and the tip broke off in the cylinder. Lots of smoke and came to a coasting stop. Tore the engine apart to find a mangled piston and ring parts. a bit interesting to see but it caused an engine replacement to a 302. Not a big deal really but with what I have invested in this 401 I'd rather not take the risk and make sure things are sound before buttoning things up and bringing it to life and start eating asphalt

 

Bottom line, plastiguage is not the perfect measuring tool. Only an outside and inside micrometer will give you that, but from the results you have I would say that you will be OK.

 

K i'll give the bearing switch a go and let ya know.

Yep using assembly lube, didn't know it could do something like that. Good to know.

I also thought of another potential while looking up intake manifold information.

Since I had the block squared and heads milled will my intake still sear correctly? It was just enough to get things leveled not an angle mill to the heads.

Thanks much!

 

I would talk to your machinist who did the machining,before moving forward & if you ? him, then gets some second opinions,like mentioned plastigauge is to check if things are close to spec. if your machinest is close by he might bring over his inside micrometer an check it,or find another source.

 

The #5 main should be close to .003, but I'd put it together. The machinist should have already checked the sizes and he should have compensated on the height (the surface where the intake sits) of the block when he decked it so everything lines back up.