Cam Bearings?

[dlafont]

I just decided to get to work on my 4.1 engine that I bought last year. It's a 291 block thats gone 10.4 in the 1/4 and had about 20 passes on it.

One of my first steps I decided to go with a roller cam upgrade before I put it in my car.

I pull the old cam out and I now think I have a problem. I think the front CAM bearing is toast. I noticed right off that the old CAM was a little tight comming out. After some gentle but firm coaxing I finally managed to pull the old CAM out. I noticed that the front CAM bearing looks scored. The other CAM bearings in the block appear OK.

Now... My question is:

1. How difficult is it to change the front CAM bearing?
2. Is it possible to replace the front CAM bearing without completely disassembling the engine? The engine has been girdled and shimmed, etc. and I don't relish the idea of a complete engine teardown.

Anybody?

Thanks,

Don

 

[87GNSteve]

There is a some concern with the 4.1 front cam bearings.
The 4.1 and 3.8 blocks differ in the front cam journal.
Did you use 3.8 cam bearings in the 4.1?
If so it may have caused oil starvation.
Make sure you have the 4.1 bearings or a cam w/ the front journal grooved.

The story behind it is mosts the 109 3.8 blocks have a grooved block for oil feeding to the front journal
4.1 and early 14 bolt 3.8 use a grooved cam bearing.
Then there is use of the cam itself with the groove, so if you were in the situation where you used the later bearing on an ungrooved block with a smooth journal cam it causes oiling problems.'

Now you can change the front bearing with out a complete tear down but you need the tool and my search of one turned up difficult. They are expensive and had to be ordered but maybe you can bring it somewhere or borrow/rent one from someone here.

If you do install it make sure you test the cam by going in and out spinning easily and the groove issues mentioned above are addressed.

 

[dlafont]

Cam bearing.

Yes the CAM that came out of the block was grooved on the bearing journal so I think it was built correctly.

I Have been doing some reading in the forums and as you indicated I have found that this is the difference between older 4.1 blocks and new turbo 3.8 blocks.

My 4.1 does not have the block with the channel in it and I suspect the CAM bearings didn't have the groove in the back of it so that is why it was probably using a grooved CAM.

Of course the roller CAM I have does not have the channel because it was made for a new 3.8 it looks like.

This means I will need to get the CAM grooved or I will have to put a channel in the back of the bearing like I have seen some do.

As far as getting a tool to push the CAM bearing out I think I have found one from Summit Racing Summit Cam Bearing Installation Tools: SUM-900130 - summitracing.com

Do you think this will work? It says it fits small block chevy's only.

Anybody can chime in with a place where I can get the CAM bearing installation tool?

I am also looking for where I can get new CAM bearings.

Thanks,

D.

 

[BlackBandit]

TA makes a killer set of cam bearings that are grooved and coated and everything. Also, you might look to eastwood tool or harbor freight for a cam installation tool. FWIW installing cam bearings is easy. HTH. james

 

[dlafont]

Cam bearings

Thanks,

I just ordered a set from TA performance. Looks like they got the grooves in the back of the bearings for this block for the oil passage.

Is it just as easy changing the Cam bearings in a built engine? That's what I need to do.

I know the tool helps get them in without the engine internals getting in the way but how do you get them out without stuff getting in the way? Is it just a matter of pounding it out from the front and letting it drop out the bottom of the engine?

Thanks,

Don

 

[BlackBandit]

You'll have to knock the cam plug out to put in the front bearing so the tool can center on that journal. I've never done cam bearing with the crank in but it should be doable. It'll probably just take time and patience. You will need something to fish the bearings in and out. Also, with the ta dual groove bearings pay attention to the instructions. They relocate the oil feed to the journal so you can't feel the oil passage through the hole in the bearing once installed. The block feed hits the groove and the groove channels it to another point. You'll see what I mean when you look at it. HTH james

Edit: Just thought of this. If you're just doing the front bearing you feed the tool in from the cam plug so the bearing will pop out the front. Then you'll feed the bearing down (somehow) into the engine and onto the tool. Lightly expand the tool and push it against the block opening. This will center it. Then expand the tool the rest of the way and drive it in.

Edit 2:If you order a cam plug from ta make sure they send you the right one. They sent me one that was two small and I forgot to call and let them know. It coulda (probably was) an honest mistake, but there data base could be wrong so double check the size when you order.

 

[bison]

I have changed the front cam bearing in a 3.8 many times. Just get a driver that fits over the bearing and drive the new bearing in and force the old one out with the new one. Be sure to drive it in till the oil holes/grooves are lined up with the feed hole in the block. The pan will need to be off to get the old bearing out. You will have much better oil pressure after the swap. I like Clevite aluminum cam bearings in the front location because they are harder and last longer when run with a grooved cam. High volume oil pumps increase the rate of wear.

 

[dlafont]

Cam bearings.

Bison, that sounds like an interesting way to get the CAM bearing replaced.
KISS principal... I like it

I imagine though that you'd have to be careful to make sure your square and lined up just right while your driving it in.

I'll take a look and see if this method might work for my 4.1.

Thanks everybody. I'll let you know how it goes once I "get my bearings".

D.

 

[bison]

Bison, that sounds like an interesting way to get the CAM bearing replaced.
KISS principal... I like it

I imagine though that you'd have to be careful to make sure your square and lined up just right while your driving it in.

I'll take a look and see if this method might work for my 4.1.

Thanks everybody. I'll let you know how it goes once I "get my bearings".

D.

Ive done it so many times in the last ten years i cant even count anymore. Usually only the front one is worn from the loading and the grooved cam. It lines itself up immediately when placing the new bearing on the old one. Just hammer it home and make sure your lined up on the oil holes. No binding or any problems related to the bearing have ever occured after i did this. There is an increase in oil pressure everywhere in the rpm range though. Make sure you have the correct cam bearing for the block you are using since there are variations. I like the clevites because their hard and the front one has a tiny groove cut into the back of it to help oil the cam thrust which has been a problem area on a lot of blocks in the last few years.

 

["More Boost"]

my machine shop installed my cam bearings, if the groove is on the back of the bearing, how can i tell if it is grooved? and please dont say just ask them because, they dont remember and i am not on speaking terms with them. i cut off all ties with them. help

 

["More Boost"]

nvm, i ordered a new set from TA perf. this morning DG DF hardened set. this way i'll know

 

[BlackBandit]

Just read the instructions with those because the oil hole does not go over the hole in the block.

 

[Sleeper-6]

AAAHhhhh!!!!!!.........Please stop using the caps lock on the work "cam" it's driving me nuts trying to read this.




OK, I'm going back to my little OCD corner now.:biggrin:

 

[HP Man]

I hope you are installing the cam brgs with the main caps torqued in place? Absolutely a HV OP will cause front bearing wear. If the cam bearing has worn then all the copper/babbit material has circulated through the block, a complete block tear down and flushing is required, do it right or engine won't last. Also the engine oil cooler will need replacing if a stock type radiator is used, you can't flush it as the internal baffels trap any metal particles. Don't know much about the grooves but my next engine (3.8) will have an ungrooved S2 front cam bearing with a single oil hole. I paid big money for this original S2 that will last, harder material etc. Gene

 

[49-blues]

what is the part number for the ta bearings for the 4.1?

 

["More Boost"]

i think she might be sending me the wrong ones, i called t/a perf. and spoke to a woman on the phone. she was very insistent that i need their 1556 bearings. even tho their online catalog states those are wrong for me. 1559 are for 4.1 according to their online catalog. (she said catalog must be incorrect) could anything else go wrong. i will have to call AGAIN monday to clarify. (unless their online catalog is in fact incorrect) will keep u informed on the part no#s

 

["More Boost"]

yes 1556 is correct for hardened dual groove dual feed cam bearings (set) for 14 bolt pan blocks. their online catalog is misleading.