1996 - 318 Engine Rebuild - guidance request

Hello all.

Can anyone please fill me in on exactly how cam shaft bearings are sized ?

I need to buy a new cam. One of the lobes on mine is kind of chewed up on one spot. The roller lifer that was riding on it doesn't appear to have any damage. I can't justify putting everything back together with that cam.

I would like to put a modified cam what gives me the most horsepower without having to change anything else. ( throttle body etc ) I was told this is possible, but I don't know what size cam to order, and I don't understand about the cam bearing size especially in an engine that was already rebuilt once. ( the pistons are 0.060 over and the main and piston bearings are 0.010 under ? is it ? )

Can someone please explain how cam bearings are sized ?

It should be noted that I saw no other wear on any of the other bearings ( no copper showing at all ) no ridges on top of the piston bore. It was like the engine was rebuilt and only ran for 10,000 miles.

However, oil was being pushed out of like every gasket, the rear main, etc .. I don't understand why oil was being pushed out from everywhere but the engine looked like brand new on the inside.

Regardless, I'd appreciate all the infromation I can get about how cam bearings are sized and such and how I can understand what cam to buy.

Thanks very much.

Your cam bearings are not sized like crankshaft bearings are. When crankshafts are remanufactured in some cases there is damage to the journals that needs to be repaired. To do this they remove enough metal from the crankshaft to give it the correct surface. In this case the bearing you would put in would be larger to accommodate the smaller crankshaft diameter. This is why you will see bearings that are 10 over or whatever they need to be to make the clearances correct. In some cases the main journals may need to have more removed than the rod journals so you may have a crank that is 20 under on the main journals and 10 under on the rod journals this is common for remanufactured engines. 10 under would be 10 thousandths of an inch. If a crankshaft has no damage it is considered a standard crank and will require standard bearings. The cam bearings are not sized if you want to replace them you just purchase the correct bearings for your engine. They will come in the standard size. If your cam journals are damaged then you replace the cam. Cam bearings don't normally wear like rod and main bearings due to the fact that they are not transferring the torque and the power through the crankshaft. If you decide to replace your cam bearings you need to have a cam bearing removal/in station tool and make sure you install them correctly so the oil journals are positioned correctly. If you are not familiar with this you may want to have them replaced by a machine shop. As far as the cam goes there are way to many factors to consider to just throw out a cam grind with lift and duration and all of the other factors that need to be considered before deciding on the cam you want. Engines are like puzzles. Everything needs to fit together in order for the engine to operate to its maximum potential. You may want to start doing some research on mild cams for your engine that won't need any other modifications to the engine that may help increase some power and torque. These are commonly referred to as RV cams.

Camshaft bearings are are usually just replaced with a new cam. They are standard sized for whichever engine they are for. Cam bearing come in a box and they need to be installed in the correct order with a spcialized tool. The largest bearing goes in the rear of the engine and every on is a tiny bit smaller as you go forward. Make sure the oil holes are lined up if you do it yourself.
Like the previous poster said you can't just throw in a cam that will give you the most horsepower. It is like dominos each component is dependant on all other components like compression ratio, cam lift and duration, rocker ratio, air/fuel ratio, exhaust system and so on.

thanks

OK. Thank You for the responses. I understand now that the cam bearings are standard sizes.

I will do some research to buy the best RV cam I can get. As I'd said I don't want to change anything else, especially the throttle body. I just don't want to get into removing all the wires and computer changes and everything else that I'd probably need that goes along with that.
I basically peeled everything off the engine and laid it aside in the engine compartment, and just want to lay it back down on the longblock after I install and boom ... good to go.

Since the cam bearings look good ( I see no wear whatsoever ) I'm not going to replace them. Even though the main and rod bearings are also in very good shape ( only the slightest wear on one side of the silver, no copper showing at all ) I'm going to replace them as a matter of course. Also going to replace the piston rings, re-lap the valves, new springs, etc.

I'm still curious as to why the engine might have been pushing oil out of just about everywhere ?
This engine was already a re-built of some sort, from the oversized rod and main bearings, and that rebuild was well over 10 years ago. I personally have put only about 20,000 miles on the truck in the 6 years that I've owned it, and I know the previous owner put less than that on it in the 5 years that he owned it. I know the engine was rebuilt before he got it as well. Could it just be that the age of the gaskets and such and the fact that I'm actually using it more was enough to sort of just start pushing the oil out ?

Thanks again for the responses and information.

Here is my wish list from summit. The quantities are not correct, as I'd need 8 of the rod bearings and 16 each of the lifters and springs.

Can someone maybe double check me and see if I'm headed down the right path ? The Cam is supposedly and RV cam that requires no modifications to the intake or heavy springs or any other changes.

Many Thanks.

*If you would like me to email the actual list to you, PM me and I'll send it directly. The copy paste doesn't transpose perfectly from summit website email.


CCA-20-744-9 - COMP Cams Xtreme Energy Camshafts CCA-20-744-9 - COMP Cams Xtreme Energy Camshafts
Camshaft, Hydraulic Roller Tappet, Advertised Duration 258/264, Lift .480/.480, Mopar, Small Block, Each
Part Number: CCA-20-744-9

$315.97
CLE-CB481P10 - Clevite P-Series Rod Bearings CLE-CB481P10 - Clevite P-Series Rod Bearings
Rod Bearing, P Series, .010 in. Undersize, Tri Metal, Chrysler, 273, 318, 340, 360, Each
Part Number: CLE-CB481P10

$9.97
CLE-MS540P10 - Clevite P-Series Main Bearings CLE-MS540P10 - Clevite P-Series Main Bearings
Main Bearings, P Series, 1/2 Groove, .010 in. Undersize, Tri Metal, Chrysler, 273, 318, 340, Set of 5
Part Number: CLE-MS540P10

$70.97
CLO-C-3028X - Cloyes Heavy-Duty Timing Sets CLO-C-3028X - Cloyes Heavy-Duty Timing Sets
Timing Chain and Gear Set, Heavy Duty, Double Roller, Iron/Billet Steel Sprockets, Mopar, 318/360, Set
Part Number: CLO-C-3028X

$46.97
DCC-4286589 - Mopar Performance High Performance Oil Pumps DCC-4286589 - Mopar Performance High Performance Oil Pumps
Oil Pump, High-Volume, Chrysler, 273/318/340/360, Each
Part Number: DCC-4286589

$62.97
FEL-KS2114 - Fel-Pro Gasket Kit Sets FEL-KS2114 - Fel-Pro Gasket Kit Sets
Gaskets, Full Set, Chrysler, Dodge, Plymouth, 318, 340, Set
Part Number: FEL-KS2114

$57.97
SLP-E-178K60 - Sealed Power Performance Piston Ring Sets SLP-E-178K60 - Sealed Power Performance Piston Ring Sets
Piston Rings, Moly, 3.970 in. Bore, 5/64 in., 5/64 in., 3/16 in. Thickness, 8-Cylinder, Set
Part Number: SLP-E-178K60

$59.97
SLP-HT2269 - Sealed Power Hydraulic Roller Lifters SLP-HT2269 - Sealed Power Hydraulic Roller Lifters
Lifter, Hydraulic Roller, Chrysler, Dodge, Plymouth, Each
Part Number: SLP-HT2269

$9.99
SLP-VS-1456 - Sealed Power Valve Springs SLP-VS-1456 - Sealed Power Valve Springs
Valve Spring, Single, 1.315 in. Outside Diameter, 1.130 in. Coil Bind Height, Each
Part Number: SLP-VS-1456

Just wondering if anyone had a chance or desire to examine this list at all, and in particular the cam entry.

I'm probably going to order all these parts later this week.

Clevites and Fel-Pro are good choices. That's what I got when I had my engine gone through.

+1 to the Cloyes. I've got the same timing set myself.

No need for the high-volume pump. I personally wouldn't bother with one unless the engine is going to regularly run and sustain high RPMs. I went with a Sealed Power standard with my freshen-up and no problems so far. The 180,000-mile lifters are still quiet.

The cam seems a fine choice for your wants and I've had my eye on that and a Crane 704111. However, the cam would be much better complimented with a different throttle body. Take it from me, a modified OEM throttle body makes a decent difference with the factory cam so that or a 52mm will work a treat with any cam swap. Also, computer reprogramming isn't required, but there is virtually no cam swap in a fuel-injected engine that won't make more power with a tune. This is especially true in our ubiquitously "death-flashed" applications.

Also consider a good set of headers. More air in needs more air out to be optimal.

Overall, it all depends on how much you want to spend vs what you want. For the most part, your list looks dandy and not much different from what I originally had planned with mine. Budget just wouldn't support the cam swap. Maybe next year, LOL.

Many Thanks for the reply.

I will be ordering these parts now, and that will be about the limit of what I can do financially at this time.

Heads and Throttle body I can install while the engine is in the truck I think, so I can always bolt those things on afterwards if I get the cash.

My cam is trashed so I have to get one regardless.

Again many thanks !

I'll post pics for everyone after the build is complete !!

Yeah, keep us posted. I'm really curious as to how that spec of cam will run.

All the parts have arrived and we are putting it together tonight, or at least starting to.

How much progress we make will depend on how many beerz we are drinking at the same time. LOL ( that's actually more my buddy than me ).

I will try to remember to get some pics along the way and I will update for sure when I pull it out of the garage.

No DIY auto work is complete without a few beers involved.

Ok --- it's been a crazy time I haven't been able to get to much, but I started to clean the pistons and I realized one of them had flaked off the edge at the top. They say that is from running the sh*tty gas we all are sold at the pumps ? Is that true ?

So now I'm looking for advice on what pistons to buy. I will be installing an RV cam so keep that in mind.

Domed or Flat Top ?
Cut-out for valves or not ( I think domed must be cut-out ) ?
cast, hyperallergenic or forged ?

I know there can be quite a difference in price from the cast to the forged, but are the hypereutectic ones sufficient ? Even those aren't cheap.

Many Thanks for the advice on this, I'm looking forward to finishing this project !

Another question I have about the pistons is more specific about the top shape.

obviously the dome has a higher compression and the dished would cause a lower compression in the cylinders.

What is the effect on low end torque / top end speed with these two different piston tops.

Thanks again for all the advice.

Just go factory replacement cast. They hold plenty of power and you don't have to worry about piston to valve clearance. Domed you're going to have clearance issues.

Forged and hyper pistons are more for serious power builds

Huh, I had thought that the factory pistons were already hypereutectic.

I wouldn't bother with fiddling with the compression ratio unless you are getting really serious. OEM compression ratio is somewhere around 9:1 which can still handily yield circa 400 horsepower with the right induction setup.

Even with an RV cam, I wouldn't have any qualm with using OEM-spec pistons. I do know that big cams need a higher compression ratio or you will throw away power and I once knew why, but I don't remember everything that I read about engines, LOL. I'm sure that there's someone here that can explain.

The only thing that I don't like, design-wise, about the OEM pistons is that the "trough" likes to collect carbon deposits which will ultimately raise compression beyond what is intended, although I suspect that this may be more of a problem with leaky intake plenums. I never like it when factory publications say that it's "normal" for stuff like this to happen though. Don't get me started on how it's considered "normal" for GM V6 engines to have noticeable piston slap when warming up...

They might be hypereutectic, i could be wrong. I was thinking they were cast but now I'm not sure.

Yep just double checked, they're cast.

OP you can get away with flat tops if yout want that slight extra compression but i would still just go with cast unless you're more serious about increasing power

Ok, so cast sounds like the way to go, and I was thinking flat top, but I was just thinking of another concern.

The engine is bored 0.060 over. What the chances that the heads have been shaved down enough during one of the rebuilds that regular flat top pistons would cause a problem ?

If I were to get 2 relief or 4 relief, would that prevent any issues, do you think ? Or do I need to go so far as to check the old pistons or actually get some things measured professionally ?

squarethumps said:

OK. Thank You for the responses. I understand now that the cam bearings are standard sizes.

I will do some research to buy the best RV cam I can get. As I'd said I don't want to change anything else, especially the throttle body. I just don't want to get into removing all the wires and computer changes and everything else that I'd probably need that goes along with that.
I basically peeled everything off the engine and laid it aside in the engine compartment, and just want to lay it back down on the longblock after I install and boom ... good to go.

Since the cam bearings look good ( I see no wear whatsoever ) I'm not going to replace them. Even though the main and rod bearings are also in very good shape ( only the slightest wear on one side of the silver, no copper showing at all ) I'm going to replace them as a matter of course. Also going to replace the piston rings, re-lap the valves, new springs, etc.

I'm still curious as to why the engine might have been pushing oil out of just about everywhere ?
This engine was already a re-built of some sort, from the oversized rod and main bearings, and that rebuild was well over 10 years ago. I personally have put only about 20,000 miles on the truck in the 6 years that I've owned it, and I know the previous owner put less than that on it in the 5 years that he owned it. I know the engine was rebuilt before he got it as well. Could it just be that the age of the gaskets and such and the fact that I'm actually using it more was enough to sort of just start pushing the oil out ?

Thanks again for the responses and information.

Click to expand...

It sounds like the engine was pressurized, forcing the oil and oil vapors out wherever it could. This could because of an inoperative pcv valve. More likely because of poor ring seal. Just slapping new rings in it might work, but it might not, too. This is best fixed by properly fitted pistons and rings, AND properly finished cylinder bores. If the cylinders haven't been honed professionally, & with a torque plate, it could be a crap shoot whether the rings will seal properly.

It sounds like the engine was pressurized, forcing the oil and oil vapors out wherever it could. This could because of an inoperative pcv valve. More likely because of poor ring seal. Just slapping new rings in it might work, but it might not, too. This is best fixed by properly fitted pistons and rings, AND properly finished cylinder bores. If the cylinders haven't been honed professionally, & with a torque plate, it could be a crap shoot whether the rings will seal properly.

Click to expand...

Thanks for the info. Major bummer, but the pressurized engine theory makes sense, though wouldn't there have been smoke out the exhaust pipe as well ? I didn't have any smoke at all.

I will be certain to get a new PCV valve for this rebuild. I guess I'm ashamed to say that we didn't use a torque plate, though, now, I know what one is and why it's better . We just used some honing stones on a drill. moderate speed and an up and down motion to achieve the crosshatch on the walls. They look pretty darn good I think, but certainly not put into perfect round during that process.