I was reading the car craft issue where they had the buick 455 with stage 2 heads on it. I noticed they said buicks have rally bad cam bearing failure. What causes it so bad in a buick and not other motors and how much of a problem is it in a street engine. Will everyone eventually see problem down the road or is it more of a race application problem?
Buick's have a very small cam dia., and that causes a lot of pressure on the cam bearing, also having the oil pump in front with the distributor puts a lot of stress on the front cam bearing(the most common to fail). Using the TA groved cam bearings is the fix(they are made of a better materal and move the oil locations where they need it most right before the load of the cam, also they flow oil around the back so if the bearing starts to fail the rest of the motor still gets oil). They also offer a coated version for added protection(the coating also aids in cam break in, which is when they fail most.
so is a street engine as hard on the bearing as race or does it all depend basically what i'm trying to ask is i used clevite bearings and have the right clearance. I used a stock oil pump and am running a 525 inch lift cam. The motor isn't turned over 5500. This type of motor is good for a couple of years right. i only drive it whens its nice and might put 1500 miles on it in a year.
Higher lift cams and heavy duty valve springs are going to increase the load on the cam bearings and reduce their life, but at 1500 miles a year you'll likely get a lot of service from them, as was said before it's believed that the bulk of the damage occurs at breakin, so if your not having oil pressure issues, or excessive valvetrain noise on the drivers side your probably in good shape. No sense looking for trouble, there's plenty that will come to ya.
The Steven Dove book recommends bronze bearings. I've also read about "double grooved" cam bearings...Where can I get some ?uzzled:
Dove Book is very OLD Newer and better technology is available today, just get the TA dual groove bearings to avoid problems, and it wouldn't be a bad idea to get the TA heavy duty rod and mains too IMHO. :TU:
Keep your old valve springs to break in the motor with. After it's broken in, put the new springs on. As mentioned earlier, cam bearings get the most abuse on initial break in. If you use the lighter (weak) springs, it won't put a severe load on the bearing.
Yes and no. Depends on the cam and valve springs. A Race engine has much more aggressive cam lobe profiles which requires higher rate valve springs to follow these lobes. This causes the additional load at the bearing surface. Of course Rpm's are much higher also. It sounds like your engine is together and running already? If so, quit worring and just make sure that you don't rev engine over 2,000 rpm's until it's up to normal operating temperature! If not, instal the dual-groove bearings in the revised oil-feed location, and check the cam for excessive runout. Unless you are using an aggressive cam and higher rate valvesprings(like a BIG solid lifter, or any roller), don't worry about breaking your cam in with anything other than the springs recommended by the cam manufactuer. IMHO
Hi Guys, I believe the leading cause of cam bearing failures is the fact that most builders do not give cam bearing clearance a second though and therefore do not even bother measuring. The clearances there are just as important as the rods and mains are. I don't think there are many out there who would build an engine and not check those out, do you?? o No: The major majority of aftermarket (non-stock) camshafts journals are in fact too big thereby decreasing cam bearing to journal clearances. If you measure a stock (GM) camshaft you will find the journals to be 1.7850 - 1.7855". Aftermarket cams are measuring from 1.7860 - 1.7865, that's a .001-.0015" decrease in bearing clearance!ou: You want (and need) .0025" clearance! You may need to have the cam journals re-polished to accomplish this. Plus you need to factor in that unless you are using TA grooved bearings, whether single or double groove, you are in fact oiling the bearing at about the 9-10 O'clock position which immediately takes the oil to the top (no load portion) of the bearing. The bottom of the bearing is the load portion as the timing chain connected to the crank is pulling the cam downward and is concentrating all the pressure in that small area alone. Now....this is greatest in the front bearing and decreases in each bearing as you move back thru them. That is why you tend to see the first one the worst and sometimes the only bearing that has went bad. With a stock bearing, as it goes bad it fills the only groove in the cam that feeds oil to the driver's side gallery as then you start to hear the dreaded lifter ticking that does seem to go away no matter how long you run the engine or how much pressure your guage reads. With the TA bearings you install them so they oil the journals at the 3-4 O'clock position and that oil immediately goes directly to the high load area. Coating your bearings can be a big help also...BUT you need to realize that it will reduce your clearance by about .0005" so plan accordingly and polish those journals. Measure, Measure, Measure! :TU: As a side note I have always broke my cams in with only the outer spring to reduce the load pushing down on the cam. Also...if you are able to afford titanium retainers and anything else to reduce valvetrain weight this will allow you to run less spring pressure and further reduce the chances of a bearing failure! :Smarty: Hope this helps....
