welli finaly started a 455 that i rebuilt. after running it for about 1 hour i pulled the intake off to check the cam bearings. they looked fine but my cam had walked to the rear of the block. the lifters were running on only half of the lobes. i need some advice on how to fix this. Thanks
Marc455, welcome aboard, sorry to hear about your problems. I am repairing a engine where this happened. My original plan was after purchasing the engine from someone was to replace the cam and install it into the car. Once I pulled the cam I saw cam walk! I don't have any solutions for you but I can share what I found with my engine. The front of the block was worn by the cam hub. The engine had a hi-volume oil pump. The dist. gear was replaced by the original builder after 50 miles. The front cam bearing was shot. Four pistons were installed backwards. Two rod bearings were about to go. I have completely disassembled everthing, and am replacing all bearings and rings. The block will be honed and a bronze thrust washer will be used behind the cam hub, after block is machined accordingly. I will be using grooved cam bearings and a standard oil pump with booster plate (no more high volume oil pump). A high volume pump could work but it's really not needed and presents a rather high risk factor in the Buick. I will also make sure the pump is set-up properly, this is very important!!! What kind of oil pressure did you have during initial start-up? What signs did you see/hear that indicated there was something wrong? Good luck and keep us posted, I'll do the same. I'm sure you will get more feedback from this great Buick community. :Smarty:
is there a way we can avoid this from happening in the first place? what is the cause of this? plan on doing a build up in a while and want to avoid any problems i can, i would like it to be a perfect world and and have everything go smooth:grin: lets see what happens.
Thanks for the reply There dosen't seem to be anything else wrong with the engine. I already have a boster plate and grooved cam bearings and a double roller timing chain installed in this engine. How can I tell if I need a thrust bearing and where can I get one.
one more thing I had 40 psi oil pres off of the pump and 30 psi at the back of the block from the rear oil galerys at 2000 rpm. Maybe the freeze plug at the rear of the cam isn't pushed in enough?? what do you think??
Marc, Since you have the intake off, why not crank the motor and observe the lifters while cranking the motor. If they are all rotating and pumping up fine, there is probably no reason to concern. Also, freeze plug should not touch the camshaft end. Make sure the camshaft isn't loading up on the front of the block. My guess is that your motor is fine. Matt
mark455, this is what my block looked like after the previous owner ran it for 60 miles or so. This is the groove in the front of the block where the cam was pushing back against the block, it is ~.027" deep. This is where the bronze thrush washer will sit after the block is machined. What cam did you use, did you measure the lobes and the amount of taper of the lobes. This taper front to back is what helps the lifters spin for a uniform ware pattern. In my opinion o No: (and it could change as I learn) here are some contributing factors to the dreaded cam walk: - High volume oil pump, or high oil pressure - An aggressive hydraulic cam - Aggressive springs, high spring pressure - Taper of cam lobes (front to back) is steep (.003" or more taper, larger width towards back of engine) I still don't know for sure why cam walk happened with the engine I now have, but it did have a high volume oil pump. Obviously this can happen anyway as in your case o No: . Anyone have other input? Jim W., Jim B.?
Thanks for the info. I am running a TA 212 from TA performance. This is a pretty mild cam. I was also doing the break in with the old valve springs from this engine. I was going to put the new ones in after the break in. I dont think there is aly damage to the engine since I only ran it for about 15 min. but I need to find out why it's doing this. Tommorow I will pull it and remove the timing cover and see if I can see anything wrong.
Thanks Mat They are all lifting and rotating like thy are supose to but they are not centered on the lobes. Do they need to be perfect. I also bent one of my new adjustable push rods.
If they are centered on the lobes, they won't spin, if at all...They need to be offset so they will spin... That is actually one of the problems with the Buick 3.8L motor that is in the GN/TRs...The #3 exhaust lobe is actually close to being centered on the lifter for some stupid reason that no one can answer and many, many aftermarket cams have been known to wipe out the #3 exh lobe, one of mine included!!! :af: :spank: :blast: As long as the lifters are spinning normally, I wouldn't worry about it...
Thanks jim Thanks, I feel much better now. I will still pull my timing cover to check to see if there is any rubbing on the block though. It wont be that much trouble since i have to pull the oil pan to install the windage try that i forgot to put in.
Actually, the front of the cam is supposed to rub on the front of the block. Oil coming out of the front of the front cam bearing should act as lubricant for the cam/block interface. Now if you wipe out the front cam bearing really bad, I suppose it would be easier for all the oil to go out the back of the bearing instead of the front. All this would surely be aggravated by a high-volume oil pump. I have seen a grooved block like that once before, but it was from the builder using too long of bolts on the timing gear. On a mopar, they actually made what was called a "low-taper" camshaft. What this did was decrease the taper of the lobes, thereby decreasing the pressure and friction imposed on the cam thrust surface via the lifters. The result was theoretically, at least, more horsepower. More cam float front to back is the result though. Using a thrust plate to limit cam walk is the answer. All roller cams have these, because with non-tapered lobes to accomodate the rollers, there is no other way to limit "cam walk."
Guys - I'm not sure if they are still being made for the Buicks, but RPM in NY used to make Rear Anti-Camwalk Units to control the endplay of the cam. I used to work there, so I'm quite familiar with these - some of you guys on the board had purchased some, so you would also be familiar with them. They worked good at keeping the cam from moving in and out. Ideally, you would want a thrust washer or a double washer/torrington bearing setup in the front of the block - the latter would require machining. The only 'downfall' of this design, was that the motor had to be out to take the cam out. Some guys were 'concerned' about the washer locating off the back of the cam bearing. We had NEVER been made aware of anyone having a problem with that! Supposedly, Mike (TA) was making a unit of his own that would locate off of the front of the block/cam. Sounded like a real good idea, when I talked to him last year at the Nats. I would suggest giving Mike a call and see if his Anti-Camwalk Unit is done or available! Limiting camwalk will get rid of alot of other problems. *Eliminates 'spark scatter' from the cam/dist. gear moving around. *Seriously extends timing chain life. Side-to-side movement if bad. *Keeps the lifters centered on the lobe - extending it's life. Even the Buick V-6's that have the rollerized cam button with a spring, have trouble with the cam still moving in and out - enough to start to bore a hole in the timing cover.
I had a 1984 mustang v6 it was designed very closely to that of the 455. I am unsure about the cam but I do know that if the bearings for the crank aren't put in facing the direction they should be then the crank would have too much play in it. I am guessing maybe the same applies for the crank and cam of a 455. Either way it sounds like you'll be pulling the engine to figure it out. :error:
Hi! I know this is a old post. Did anyone ever find a "bearing "setup ? I have a problem with the cam eating the front of the block and am wanting a bearing setup instead of a thrust washer. I phoned TA yesterday and they only had a thrust washer. I understand I'll have to machine the block to suit either setup. Thanks Brad
