misaligned block cam journal

[F-250 Restorer]

Hey guys. The second cam journal in my block is slightly out of alignment. I had to chamfer the leading edge of the bearing to get the cam to slide in. Once in, I could feel it was tight/stiff to rotate. Installed all the way, with both hands holding the cam gear, it is stiff to rotate. Am I making a mistake by continuing to build this block?

[pmuller9]

There are two different sets of cam bearings.
One set for 1965 to 1985 and another for 1985 midyear to 1996.
I believe the later block and cam bearings have a smaller OD for the center two bearings.

[F-250 Restorer]

I have the earlier block, so the later bearing choice would not affect the insertion of my cam. The ID would be the same, right.

If the cam is tight as it is, am I making a mistake by proceeding with this block?

[pmuller9]

If the late model cam bearings are installed in the early block the cam will not go into the outer bearing by a long shot.
I tried that one. LOL.
It could be the bearing is undersized.
Is the cam touching the bearing surface all the way around or on just one side of the bearing?

[F-250 Restorer]

Good point. I will check, but I'm pretty sure the bearing is touching all the way around. It has done this with two sets of cam bearings, the second set purchased and installed by a machine shop so I could make sure I had it right.

Should a cam be stiff to turn?

[pmuller9]

If it is touching all the way around then the cam bore is straight.
The cam should be easy to turn with the cam gear.

Check the cam journals with a micrometer to see if they are correct.

If the cam journals are good, If you install the cam from the back of the block does it still wait for the second bearing from the front to get stiff to turn.

If it turns out to be just the second cam bearing bore you can simply hone a bearing ID for that spot.

[F-250 Restorer]

Thanks, I will ck all that. I saw that the cam was hitting the bottom of the bearing, so I chamfered the edge and sanded the bearing with 400 w/d sand paper, and then was able to slide the cam in. I'm guessing I should have sanded a bit more? until the cam is easy to turn?

I have a 'spare block with 40k miles on it. I'm tempted to use it instead and bypass any issues that may arise from sanding the bearing.

[Max_Effort]

Could be a few good things, the cam itself might be a bit bent.
The bearing was slightly hurt going in - or a little scraped on the back side.
It could be the cam tunnel alignment, but I didn't think these blocks are known for that.

If you have a clean used camshaft, slide it in, then, with a 3'lb hammer and drift (blunt, preferably brass) , knock it from the bottom and and the top up and down near the journals, not really hard, just a few solid hits. This will often fix the issue.

Personally, I don't like any abraisive on bearings. On some notorious blocks (i.e. BB Mopar) I make a scraper tool from a used camshaft by cutting a slot in the journal.

[F-250 Restorer]

Thanks for all the suggestions and feedback. The journal is misaligned. The cam hits on the bottom of the bearing. If I do anything to remove some of the bearing surface and allow the cam to spin freely, that means there is that much play/gap on the other side of the bearing. If I remove .001-.002" to free up the cam, then there is that much gap on the other side. That is what scares me. This engine lost oil pressure once before, and now I'm afraid to try anything that may result in low or dropping oil psi.

I have another engine with 40k miles on a fresh bore. I think I'll loan a reamer and remove the ridges, run a hone through the cylinders, and swap the inards into this block. Problem solved with no risk.

[pmuller9]

Sounds like a good plan.
If the cam bore is out of line the main line may be out as well.

[F-250 Restorer]

I pulled the cam out. Then I tried it in only three of the journals, and then in two. What I found was that it seemed to get difficult to turn as the cam entered the rear side of a couple of the journals. So I decided to just take some four hundred wet and dry sandpaper and sand that area on those journals a little bit. I did that and cleaned up and then reinstalled the cam. Now it spins freely and it appears to be touching each journal 360°.

Of course the problem now is that I don't know how the heck to proceed. It just about scares me to death to think that this engine might lose oil pressure as this block did once before with a different rotating assembly in it. I am leaning towards just moving forward with this engine. I like that better than putting new pistons and rings and whatnot into a bore with 40,000 miles on it.

If anybody has any reason why I should not continue building this engine, or is able to deduce some problem that might occur with this camshaft situation, then I'd really like to hear from you. Thanks.

[pmuller9]

Is the main line for the crank straight?

[wallen7]

In my years of experience if a cam bore is out of position, the cam will break after a couple of thousand miles.
I experienced this several times when I worked for a Ford dealer.

[F-250 Restorer]

Is the main line for the crank straight?

It seems to be. The crank spins easily.
I guess the only way to be certain that the engine is good is to abandon this block and use the other one. OK. That is what I'll do today.

[pmuller9]

Is the other block already 4.030" bore?

[F-250 Restorer]

Is the other block already 4.030" bore?

Yes.

[MechRick]

I've run into this on Ford V8's. It's not uncommon to have to 'relieve' a cam bearing slightly. As long as it's limited to one edge of the bearing (and not the entire bearing) it should be fine.

I had a 460 apart once that a remanufacturer had ground the cam bearing journals smaller (to save the cam) and installed under size bearings, which were reamed to (under) size. Are under size bearings available for the six?

You can make a bearing scraper out of an old cam, as the link below suggests.

http://suicideslabs.com/dw/engine/alex379/alex379a.htm

[Max_Effort]

If the cam turns freely, it will be fine.
If the crank turns freely in torqued mains, with normal bearing clearance, it's also going to be fine.

[F-250 Restorer]

Sealed power makes a set of undersize bearings, main bearings, for the three hundred. I found them on rock auto,.001 under the standard size.

Well I guess the three hundred doesn't like me. Today I took the rotating assembly out of the first block with the misaligned cam. I guess what the other forum members said about how a misaligned cam will cause the cam to break after a short time scared me.

When I got the crank in the second block I found that the mains were out of spec. They were beyond the .0015 limit in the book. On the other block, with the same bearings and crank, they came in at the small end of the range that the book said. I thought that was strange. That was with .001 undersize bearing! That left me scratching my head.

I wish I had gotten the replies from the other forum members before I had taken the first engine apart. The crank and the cam both spun freely in the first block, and that was with the crank torqued down.

I don't want to have this crank turned down since it's already been balanced and polished.

Thanks for the replies in the great information guys.

[Max_Effort]

Sealed power makes a set of undersize bearings, main bearings, for the three hundred. I found them on rock auto,.001 under the standard size.

Well I guess the three hundred doesn't like me. Today I took the rotating assembly out of the first block with the misaligned cam. I guess what the other forum members said about how a misaligned cam will cause the cam to break after a short time scared me.

When I got the crank in the second block I found that the mains were out of spec. They were beyond the .0015 limit in the book. On the other block, with the same bearings and crank, they came in at the small end of the range that the book said. I thought that was strange. That was with .001 undersize bearing! That left me scratching my head.

I wish I had gotten the replies from the other forum members before I had taken the first engine apart. The crank and the cam both spun freely in the first block, and that was with the crank torqued down.

I don't want to have this crank turned down since it's already been balanced and polished.

Thanks for the replies in the great information guys.

What is the clearance you measure now? .001” undersized bearings will result in less clearance than STD bearings.
If you need more clearance, go back to STD bearings.

In fact, it’s not unusual to mix STD and .001” bearing halves to get the clearance needed.
On popular engines, +.001 are availible too.

The housing size (The diameter of the block main or rod bore) changes the clearance. If you measure the two blocks with mains torqued you will find a difference.

Note: I haven’t ever had a cam, that turned freely in the bearings, break or spin a bearing. It’s not unusual to “tweak” things to get it to work. It happens at times, more on some engines than others. Yes, you can bore and hone cam tunnels, but that is a major expense not needed for the average rebuild.

[F-250 Restorer]

Interesting about using under-sized and standard size bearing, mixing them.

The problem I have with the new block is that the book says iirc .0005--.0015 for the mains. I measure larger than that. But that is not a problem. I'll just swap the crank and bearings back to the first block where the tolerance was within limits. I should have the rotating assembly finished today.

[pmuller9]

We mix and match rod and main bearing all the time to get the correct bearing clearance.

I run between .002" and .0025" main and rod bearing clearance on a high performance 300 build.
I would run .0015" on your engine.

If the cam turns freely and is not bent it will not break went running.

[Fordman75]

If those clearances bug you run a HV oil pump.

[MechRick]

When I got the crank in the second block I found that the mains were out of spec. They were beyond the .0015 limit in the book

My first 300 six went 285,000 miles before a carb bellcrank screw decided it wanted to be on top of #1 piston. This was an engine that rattled so bad on startup it would make your teeth itch. But once it was running and built up oil pressure the thing was quiet, no oil lamp on, and ran just fine.

On teardown, there was more than .0035" clearance between the mains and rods.

Stock oil pumps are fine on this engine.

In fact, it’s not unusual to mix STD and .001” bearing halves to get the clearance needed

Many performance engines use 'select fit' main bearings (Yamaha/SHO is one of them). Pain in the a$$ to set up.

[F-250 Restorer]

If those clearances bug you run a HV oil pump.

One of the reasons for pulling my engine was that I had to use 20/50 oil to get 10psi, with a HV pump. I want to be able use normal oil w/o a hv pump, and maintain good oil psi.

Btw, what do you guys think of my pan with clear on it?

[Econoline]

Have you had someone put the cam on v blocks to see if it's bent? The cam seems to be the constant in this story.

[F-250 Restorer]

I did not ck the cam because the tale involves one block and 2 new cams. Each cam had trouble entering the same journal in the block.

**Guys, I have to mention something you may find interesting or already know. So, about 4 days ago when the temp was about 12* warmer here, I measured in the afternoon the main bearings on my engine and they showed I had just under .0007. Four days later, when the temp is 12* colder, in the morning I check the same main, same engine everything, the same journal is .0015.

Can temp make that much of a difference?

[Fordman75]

If those clearances bug you run a HV oil pump.

One of the reasons for pulling my engine was that I had to use 20/50 oil to get 10psi, with a HV pump. I want to be able use normal oil w/o a hv pump, and maintain good oil psi.

Btw, what do you guys think of my pan with clear on it?

The problem with your other block was most likely the shifted cam journal opening. If your cam journal was tight on the bottom of the bearing. That means it's going to be loose at the top which will bleed off a the pressure.

[sandboxer]

Love the clear. Artistic.

[Max_Effort]

A small amount of extra clearance at one cam bearing isn't enough to drop oil pressure to 10psi with an HV pump and 20w50.

There had to be a lot more going on. I would be interested in what was found on the teardown. How was the bearing clearance, conditon of all parts including, bearings, journals, oil pump, pick-up, block, etc...

[MechRick]

Guys, I have to mention something you may find interesting or already know. So, about 4 days ago when the temp was about 12* warmer here, I measured in the afternoon the main bearings on my engine and they showed I had just under .0007. Four days later, when the temp is 12* colder, in the morning I check the same main, same engine everything, the same journal is .0015.

Can temp make that much of a difference?

Are you checking with mics or plastigauge?

Temp *does* make a difference, which is why you are not supposed to handle vernier calipers too much before a measurement (warms up from your hands and changes things), but 12 degrees isn't a big temp difference...

[F-250 Restorer]

I think maybe the block was still cold from the night, since it was morning. That is fascinating the with calipers. I didn't know that.
I was using Plastigauge.

[CNC-Dude]

Yes, it's called "thermal expansion. You also need to let all the components involved acclimate to the same temperature in the same room, including micrometers, dial bore gauges and engine parts. That really makes a difference, and 10 degrees can make a big difference, especially when you are measuring in tenths. That's also why things such as valve lash are set with the engine at operating temperature instead of cold.

[sandboxer]

That’s why I never turn down the heat in my shop at night. It would affect all my tools and machines.