I was running the Comp Cams 288AR solid roller in my 427 When I built my current motor (502 Gen VI) in 2001, I decided not to use a Gen VI cam, but instead adapt the 288 roller. I used the needle cam button, but had to machine it to make it shorter, and also machined the inside of the 502 Al. timing cover. All was well until last year when suddenly the motor sputtered and stopped. Removed the intake and saw the cam "walk forward" so that the lifters were off the lobes. In fact a lifter was between the cam lobe and the block preventing any further movement.

At that time I went to the shop that did the machine work, only thing the guy could come up with...too much clearance between the cam button and timing cover. Well, I shimmed the button, used a dial gague, to determine .010" clearance. At that time I also called Comp Cams, but they were clueless as they knew of no such installation.

This past week I had to remove the deep pan as I bottomed out and caved in the bottom...what dis I see? Tiny metal chips. My guess the cam button got chewed up, meaning the cam will be "walking" forward again.

I was too sick to do anything, so I straightened the bottom of the pan, cleaned it. I also pulled a rod cap, found one tiny sliver..the bearing has a groove, but crank journal is fine.

Ordered a Billet with a 308AR grind from Comp Cams for motor..will be pulling all the rod caps and....see if any damage further damage. Regardless, I'll replace all the rod bearings.

Now the tech question...assuming the rod and main journals are not scored, but the main and rod bearings show grooves from metal chips, how difficult is it to remove the upper main bearings, and what is the procedure? Loosen all the main bolts a tad or just do one main at a time?

I know the proper way would be to pull the motor, and boil the block, but at this point am looking for options.

Thanks

 

Why can't you loosen all the mains and one by one push the upper main bearings around the crank and out?? This is what the corvette manual recommends. Find the little tang on the bearing and from the other end push the bearing out.
That sucks but you have to find out why the cam button is eating the timming cover. I personally would rather have a steel cover. I used a slug of stainless about 1/8th thick and 1 inch in diameter and welded it to the inside of my cover for a place for the cam button to rub against.

 

That's what I was thinking, loosen all the mains a tad, then remove and replace one main at a time....I was concerned about getting the proper torque as there would be considerable wight on the bottom of the caps.

I am assuming the button got chewed. I have to use the aluminum cover as I am using the one piece seal and the Gen VI pan...can't mix the pan and the timing covers...either both are the old style Mark IV or the Gen VI.

 

In retrospect, I should have used the solid aluminum button....

 

Forgive the ignorance, but I assume this is a two bolt main? If four bolt, I doubt that it would matter at all. The more I think about it, I doubt that it will matter on a two bolt either. You've got full metal contact long before you reach the torque spec and I doubt that the added weight would make that much of a difference. Paranoia dictates that you aim for the high end of the torque spec though.

 

Nope, 4 bolt...The 502 blocks are 4 bolt.

If I want to be **** about it, I could pick up a pair of tube jacks. Have a couple short pieces of 4 x 4, when the bearings are replaced, jack the crank till it bottoms on the bearings, this way the bolts won't be pushing the crank up, and less strain on the threads...anyway, just a thought, will see how it goes without the jacks.

 

I believe that the difference in torque due to the load would be negligable but I think I just thought of a way to check, if for no other reason than to give you a level of comfort.

Torque up the middle journal first, then do the rest of them. When you go back to check the first one that you did, the load will be better distributed. If there is a significant loss of torque, then the load was a significant factor.

Just a thought.

 

Thanks...I'll do that...

 

I have a chart someplace of clamping force vs torque in the different size bolts. The clamping force is in the 10's of thousand. The weight of the crank will not NO affect on the torque numbers.
Also since you torque in stages work back and forth just like you do heads and the other mains will take up the wieght in stages.
Again I don't believe the weight of a crank will influence the torque values.

 

Weight of the crank will have no effect on torque values. You are acually "tensioning" the bolt/stud when you torque them not picking up on the crank. Think of it this way, if you had a cast crank that weighed 12 lbs. less than a steel one, you wouldn't lessen the torque value by the weight difference. Hope this helps.

ltlevil

 

In another life before I had any intelligence, I ran a 12.40 sec 340 Duster at the drags. I had big bearing problems due to the poor oiling system on the As eries Mopar engines. I had a proceedure that worked fairly well on dropping th eoil pan and getting the bearings out of the main saddles using a roll pin inserted into the oil passage of the crankshaft. I would pull the motor down and amke sure all the debris are out of the motor, I know it is a PITA but, if you miss something, you will be sorry later. Their is also a camshaft end play set-up that takes the place of the rear cam plug in the block and is far easier to set-up than atiming cover end play device. I'll try to get the information from my friend with the machine shop and forward it to you. Sorry to hear about the problems, hope everything goes well from here onward.

 

Hate to hear it.

You can replace mains easily..done it many times.

The only real thing you have to do it make sure the fan belt isn't tight...it WILL hold up on crank enough to make it tough to remove bearings.

Otherwise, I just loosen them all slightly, and then start at front. You don't HAVE to loosen them all, but it helps. When you drop front cap, you will be able to use a screwdriver to push up on bearing from the side opposite the tang and start it coming out. At that point once you get a 1/4" rotated you can use a screwdriver or your fingers to squeeze it back up against crank journal and roll it out. If it doesn't move, you can slightly rotate crank while pressing in on bearing shell against journal. It will easily rotate out. Then immediately roll new bearing back in just opposite of the way you pulled the old one. When you get it to the last 1/4" or so, once gain, carefully use a screwdriver to push it on around and up flush to block. Install new lower half and reinstall cap. Pay attention to the tangs...they go together on same side..easy to get mixed up when laying on your back!

I just lightly snug the cap back up then move to next one.

Alternative is to leave the center (or maybe #2 cap) and #5 slightly snugged and change the other 3 mains. Doesn't really matter.

When you get to #5 do it the same way. Good time for a new rear seal, plus I always stagger the seal halves to help leaks. Don't forget to install oil pump drive shaft when you put pump in!

You can use regular motor oil for all this. Try to keep back side of bearings dry. That's why I say to immediately install upper back in there..less chance for oil to get between shell and block.

It's really a pretty easy job..just messy.

Have fun!!

As a side note...I've seen some plastic thrust bumpers do very well. We just tore down a 30K+ mile 540 with one in it that looked brand new. I have the roller type in mine with no issues agaisnt aluminum cover...but I ran it against a stock cover in the past too. All that said..the plastic ones seem to do well....just one less little pile of metal parts to get loose in motor!

Don't worry about TQ readings issues..just TQ them up as usual. You will be applying same TQ to fasteners.

Did you order an iron cam gear on the new billet cam? I've used that 308* cam before in a 454". It did pretty well, but expect a BIG difference in manners over your old 288*. If you haven't locked in onit already, there may be some better choices out there.......you have enough cubes though...the 288* was a little small anyway right? But it is a sweet little cam though.

JIM

 

Yep this is the way to do it. I've done this on engines while still in the vehicle and never had an issue.

 

I have replaced thousands of main and rod bearings in mounted engines in my career. Here is how it should be done, but there are many ways that work.
1- remove the plugs to reduce compression drag
2- loosen fan belt to alt/wp
3- remove pan and clean everything
4- remove only one cap at a time (loosening more than one increases drag on the crank due to flexing of the crank) also if you remove more than one, DO NOT let sit overnight.
5- there are "T-Bar" bearing removal tools that fit into oil hole so you can spin the crank and it rotates the bearing right out without marring the bearing surface, you need the right size, if it is too thick it will dig into the crank. They can be picked up at some speed shops and diesel tool suppliers. Or you can make one with a small carriage bolt cut down to fit in the oil hole and the head ground down some and then smoothed out to prevent damage to crank.
6- do one then torque and go to the next.

vic

 

Here is apic of one of the "T-Bar" bearing removers, It swivels at the "T" so the shaft can go int the oil hole at the angle that the hole is drilled into. pic is fuzzy

vic

 

Jim the screw driver scares me. I prefer a piece of wood doweling. If you slip with the screw driver you could gouge the crank or bearing. A wooden dowel won't hurt anything.
I also keep a number of pieces of brass rod in the tool chest for things like this.

 

Thanks guys....I'm going to replace the cam and the bearings at the same tiime.

Jim, my thoughts exactly on the 288 cam. I'm sorta locked in on the 308, but was informed that production is backed up and won't be ground till Tues or Wed. What do you suggest? Maybe I can cancel without taking a huge hit.

 

I agree the wood dowel would work too....I just have always used a small screwdriver laid "flat" and it worked fine. Never really gets near journal. When I use one to help pry it out after it gets started, I use a longer one and lay it against pan rails. Works perfectly,,,but it may be just luck from experience. used to do it for a living way back when....

You can also make a rotator tool as described with a large cotter pin. Either way, they come out pretty easily.

You can do it only one cap at a time, but the crank isn't going to flex. It will angle down slightly with 1st 4 bearings loosened.(we're only dealing with a few .000's here max, so any extra gained is huge as far as making room for bearing to get out.)

Once again, they will come out either way you feel comfortable doing it.

Man, there are so many cam choices out there these days, but I've tried quite a few of them. There are many ways to go about it, using a catalog cam or specing your own. If you like Comp stuff, I'd get a catalog and really disect the lobe listings. You can spec a neat cam doing stuff like using an "intake" lobe on both lobes and other things. That 308 has a lot of seat duration comapred to what is out there these days and instead of the 110 LSA you might want to slip out to a 112. I've run several combos and can help give a little insight.

Give me an idea of what you're looking for. Gears, trans ratios, compression, heads etc. You have the 533 right? I just can't remember the details. I can imagine how the 288* ran...so tell me what you liked best about it and what you want it to do more of.

JIM

 

Yep...533, SRP's 10.5 C.R., the heads are over the counter 077's, aluminum w/2.19 intakes, 1.88 ex., valve pockets blended, running the factory flat tri power. I know, I know, old stuff, but I like the BB hood better than the L-88. Right now, the 533 runs great, no bog, instant response...regardless what gear I'm in I mash it, and off like a shot out of the cannon. I know there are serious limitations with the vacuum secondaries and the whole tri power setup when compared to a single 850 or a 1050.

I do have to watch how I drive as the tires break loose at an instant if too much gas. Tranny is an original Doug Nash 4 + 1 with 3.27 first gear and 3:55's in back...gives me, what something in the 5's in gears 1-4.

I'm not after the very last pony, but want to be semi competitive and not be embarrased should I ever come up against a stout machine. Street manners I like about the 288, plus the response and power throught out the rpm range. It pulls great all the way to 7K.

 

If your worried about the weight of the crank, they why not just roll the vette on it's roof when you re-torque???


Torquing the caps with the block upside down won't make any difference....
And when you get done, you can go microwave a CD...just use a plate when you do it...